Legg Mason (LMHA) 10-Q5 Feb 202020 Q3 Quarterly reportFinancial data

Company Profile

Cover Page Document and Entity

Cover Page Document and Entity Information - shares	9 Months Ended
Cover Page Document and Entity Information - shares	Dec. 31, 2019	Feb. 03, 2020
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-08529
Entity Registrant Name	LEGG MASON, INC.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	52-1200960
Entity Address, Address Line One	100 International Drive
Entity Address, City or Town	Baltimore
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	21202
City Area Code	410
Local Phone Number	539-0000
Title of 12(b) Security	Common stock, $0.10 par value
Trading Symbol	LM
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		86,892,028
Entity Central Index Key	0000704051
Current Fiscal Year End Date	--03-31
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2020
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Receivables:
Fixed assets, net	$ 138,835	$ 149,989
Operating and Finance Lease, Right-of-Use Asset	295,665	0
Current Liabilities
Long-term Debt, Current Maturities	0	250,301
Operating and FInance Lease, Liability, Current	77,377	0
Operating and Finance Lease Liability, Noncurrent	285,911	0
Long-term debt, net	1,972,413	1,971,451
REDEEMABLE NONCONTROLLING INTERESTS	$ 668,353	$ 692,376
STOCKHOLDERS' EQUITY
Common Stock, Par or Stated Value Per Share	$ 0.10	$ 0.10
Common Stock, Shares Authorized	500,000,000	500,000,000
Common Stock, Shares, Issued	86,821,437	85,556,562
Liability, Defined Benefit Pension Plan, Noncurrent	$ 30,266	$ 33,335
Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Current Assets
Cash and Cash Equivalents	823,665	921,071
Restricted Cash and Cash Equivalents, Current	17,666	21,213
Receivables:
Investment securities	408,945	377,129
Other current assets	85,410	82,131
Other non-current assets	157,938	145,254
Current Liabilities
Other current liabilities	101,150	99,479
Consolidated Investment Vehicles [Member]
Current Assets
Cash and Cash Equivalents	7,320	4,219
Receivables:
Investment securities	105,810	129,627
Other current assets	406	1,889
Other non-current assets	3,942	8,993
Current Liabilities
Other current liabilities	1,363	5,742
Consolidated Legg Mason, Inc.
Receivables:
Investment advisory and related fees	461,790	425,470
Other receivables	64,920	57,107
Total Current Assets	1,975,932	2,019,856
Fixed assets, net	138,835	149,989
Intangible assets, net	3,377,517	3,386,759
Goodwill	1,896,097	1,883,554
Deferred income taxes	193,792	199,717
TOTAL ASSETS	8,039,718	7,794,122
Current Liabilities
Accrued compensation	591,554	571,301
Accounts Payable and Accrued Liabilities, Current	159,415	182,921
Total Current Liabilities	930,859	1,109,744
Deferred compensation	104,819	85,548
Deferred income taxes	181,115	123,420
Other non-current liabilities	60,971	122,044
Long-term debt, net	1,972,413	1,971,451
TOTAL LIABILITIES	3,536,088	3,412,207
REDEEMABLE NONCONTROLLING INTERESTS	668,353	692,376
STOCKHOLDERS' EQUITY
Common stock, par value $.10; authorized 500,000,000 shares; issued 85,533,667 shares for December 31, 2018 and 84,606,408 shares for March 31, 2017	8,682	8,556
Additional paid-in capital	2,119,181	2,039,671
Employee stock trust	(20,108)	(21,416)
Deferred compensation employee stock trust	20,108	21,416
Retained Earnings (Accumulated Deficit)	1,804,251	1,742,764
AOCI Including Portion Attributable to Noncontrolling Interest, before Tax	(127,402)	(131,236)
Stockholders' Equity Attributable to Parent	3,804,712	3,659,755
TOTAL STOCKHOLDERS' EQUITY	3,835,277	3,689,539
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	8,039,718	7,794,122
Management Equity Plan [Member] \| Royce [Member]
STOCKHOLDERS' EQUITY
Stockholders' Equity Attributable to Noncontrolling Interest	$ 30,565	$ 29,784

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Consolidated Statements of Income - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
OPERATING REVENUES
Total Operating Revenues	$ 753,914	$ 704,322	$ 2,202,538	$ 2,210,654
OTHER NON-OPERATING INCOME (EXPENSE)
Net Income (Loss) Attributable to Noncontrolling Interest	16,228	10,498	41,895	31,043
Consolidated Legg Mason, Inc.
OPERATING REVENUES
Total Operating Revenues	753,914	704,322	2,202,538	2,210,654
OPERATING EXPENSES
Compensation and benefits	375,033	316,876	1,132,588	1,043,329
Distribution and servicing	104,363	108,842	313,368	339,959
Communications and technology	57,101	56,664	166,328	170,893
Occupancy	32,490	24,077	84,923	76,333
Amortization of intangible assets	6,004	6,089	16,903	18,371
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)		365,200		365,200
Contingent consideration fair value adjustments	0	0	(1,165)	571
Other	48,929	63,001	150,687	171,021
Total Operating Expenses	623,920	940,749	1,863,632	2,185,677
OPERATING INCOME	129,994	(236,427)	338,906	24,977
OTHER NON-OPERATING INCOME (EXPENSE)
Interest income	2,882	3,126	9,539	7,992
Interest expense	(27,032)	(28,770)	(82,846)	(88,547)
Total Other Non-Operating Income (Expense)	(5,327)	(30,317)	(29,337)	(71,764)
INCOME BEFORE INCOME TAX PROVISION	124,667	(266,744)	309,569	(46,787)
Income tax provision	33,664	(60,354)	80,466	165
NET INCOME	91,003	(206,390)	229,103	(46,952)
Net Income (Loss) Attributable to Noncontrolling Interest	16,228	10,498	41,895	31,043
NET INCOME ATTRIBUTABLE TO LEGG MASON, INC.	$ 74,775	$ (216,888)	$ 187,208	$ (77,995)
NET INCOME PER SHARE ATTRIBUTABLE TO LEGG MASON, INC. COMMON SHAREHOLDERS
Basic (in dollars per share)	$ 0.83	$ (2.55)	$ 2.09	$ (0.95)
Diluted (in dollars per share)	$ 0.83	$ (2.55)	$ 2.08	$ (0.95)
Consolidated Investment Vehicles [Member]
OTHER NON-OPERATING INCOME (EXPENSE)
Other income (expense), net	$ 814	$ 2,369	$ 14,904	$ 1,954
Separate Accounts [Member] \| Consolidated Legg Mason, Inc.
OPERATING REVENUES
Revenue from Contract with Customer, Excluding Assessed Tax	266,609	256,657	791,488	778,119
Mutual Funds [Member] \| Consolidated Legg Mason, Inc.
OPERATING REVENUES
Revenue from Contract with Customer, Excluding Assessed Tax	378,995	361,173	1,121,572	1,128,660
Performance Fees [Member] \| Consolidated Legg Mason, Inc.
OPERATING REVENUES
Revenue from Contract with Customer, Excluding Assessed Tax	39,407	12,619	81,137	68,529
Distribution and Shareholder Service [Member] \| Consolidated Legg Mason, Inc.
OPERATING REVENUES
Revenue from Contract with Customer, Excluding Assessed Tax	67,634	72,185	204,635	230,449
Service, Other [Member] \| Consolidated Legg Mason, Inc.
OPERATING REVENUES
Revenue from Contract with Customer, Excluding Assessed Tax	1,269	1,688	3,706	4,897
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
OPERATING REVENUES
Total Operating Revenues	753,983	704,477	2,202,888	2,211,115
OPERATING EXPENSES
Total Operating Expenses	623,817	940,561	1,862,253	2,184,807
OPERATING INCOME	130,166	(236,084)	340,635	26,308
OTHER NON-OPERATING INCOME (EXPENSE)
Other income (expense), net	18,009	(7,042)	29,066	6,837
Total Other Non-Operating Income (Expense)	(7,300)	(32,158)	(40,072)	(74,131)
INCOME BEFORE INCOME TAX PROVISION	122,866	(268,242)	300,563	(47,823)
Income tax provision	33,664	(60,354)	80,466	165
NET INCOME	89,202	(207,888)	220,097	(47,988)
Net Income (Loss) Attributable to Noncontrolling Interest	14,427	9,000	32,889	30,007
NET INCOME ATTRIBUTABLE TO LEGG MASON, INC.	$ 74,775	$ (216,888)	$ 187,208	$ (77,995)

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - Consolidated Legg Mason, Inc. - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
NET INCOME	$ 91,003	$ (206,390)	$ 229,103	$ (46,952)
Other comprehensive income (loss):
Foreign currency translation adjustment	43,933	(14,012)	3,761	(82,032)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	(1,174)	354	73	1,447
Total other comprehensive income (loss)	42,759	(13,658)	3,834	(80,585)
COMPREHENSIVE INCOME	133,762	(220,048)	232,937	(127,537)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	(16,224)	11,425	(42,728)	36,052
COMPREHENSIVE INCOME ATTRIBUTABLE TO LEGG MASON, INC.	149,986	(231,473)	275,665	(163,589)
AOCI Attributable to Parent [Member]
Other comprehensive income (loss):
Foreign currency translation adjustment	(1,174)	354	73	1,447
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	$ 43,933	$ (14,012)	$ 3,761	$ (82,032)

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Consolidated Legg Mason, Inc.	Consolidated Legg Mason, Inc.COMMON STOCK	Consolidated Legg Mason, Inc.ADDITIONAL PAID-IN CAPITAL	Consolidated Legg Mason, Inc.EMPLOYEE STOCK TRUST	Consolidated Legg Mason, Inc.DEFERRED COMPENSATION EMPLOYEE STOCK TRUST	Consolidated Legg Mason, Inc.RETAINED EARNINGS	Consolidated Legg Mason, Inc.ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS), NET	Royce [Member]	Management Equity Plan [Member]Royce [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption \| Accounting Standards Update 2014-09 [Member]							$ 12,263
Stockholders' Equity Attributable to Parent, Beginning of Period at Mar. 31, 2018			$ 8,461	$ 1,976,364	$ (21,996)	$ 21,996	1,894,762	$ (55,182)
Stockholders' Equity Attributable to Noncontrolling Interest, Beginning of Period at Mar. 31, 2018										$ 27,731
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest									$ 6,583	6,583
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	$ (25,538)									(6,820)
Stock Issued During Period, Value, Stock Options Exercised			19
Stock options exercised				5,814
Deferred compensation employee stock trust			1	468
Stock-based compensation			112	49,195
Employee tax withholdings by settlement of net share transactions			(40)	(15,506)
Adjustments to Additional Paid in Capital, Fair Value				12,251
Shares Issued to plans					(469)	469
Distributions and forfeitures					1,082	(1,082)
Net Income Attributable to Legg Mason, Inc.		$ (77,995)					(77,995)
Dividends declared							(90,345)
Vesting/Change in Estimated Redemption Value							(14,868)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax		1,447						(82,032)
Foreign currency translation adjustment		(82,032)						1,447
Ending Balance at Dec. 31, 2018		3,652,683
Stockholders' Equity Attributable to Parent, End of Period at Dec. 31, 2018		3,625,189	8,553	2,028,586	(21,383)	21,383	$ 1,723,817	(135,767)
Stockholders' Equity Attributable to Noncontrolling Interest, End of Period at Dec. 31, 2018										27,494
Common Stock, Dividends, Per Share, Declared							$ 1.02
Stockholders' Equity Attributable to Parent, Beginning of Period at Sep. 30, 2018			8,550	2,013,541	(22,117)	22,117	$ 1,981,939	(122,109)
Stockholders' Equity Attributable to Noncontrolling Interest, Beginning of Period at Sep. 30, 2018										28,074
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest									1,646	1,646
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders										(2,226)
Stock Issued During Period, Value, Stock Options Exercised			3
Stock options exercised				583
Deferred compensation employee stock trust			1	166
Stock-based compensation			0	14,380
Employee tax withholdings by settlement of net share transactions			(1)	(84)
Adjustments to Additional Paid in Capital, Fair Value				0
Shares Issued to plans					(167)	167
Distributions and forfeitures					901	(901)
Net Income Attributable to Legg Mason, Inc.		(216,888)					(216,888)
Dividends declared							(28,904)
Vesting/Change in Estimated Redemption Value							(12,330)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax		354						(14,012)
Foreign currency translation adjustment		(14,012)						354
Ending Balance at Dec. 31, 2018		3,652,683
Stockholders' Equity Attributable to Parent, End of Period at Dec. 31, 2018		3,625,189	8,553	2,028,586	(21,383)	21,383	$ 1,723,817	(135,767)
Stockholders' Equity Attributable to Noncontrolling Interest, End of Period at Dec. 31, 2018										27,494
Common Stock, Dividends, Per Share, Declared							$ 0.34
Stockholders' Equity Attributable to Parent, Beginning of Period at Mar. 31, 2019		3,659,755	8,556	2,039,671	(21,416)	21,416	$ 1,742,764	(131,236)
Stockholders' Equity Attributable to Noncontrolling Interest, Beginning of Period at Mar. 31, 2019										29,784
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest									5,300	5,300
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	$ (22,775)									(4,519)
Beginning Balance at Mar. 31, 2019		3,689,539
Stock Issued During Period, Value, Stock Options Exercised			37
Stock options exercised				11,612
Deferred compensation employee stock trust			1	525
Stock-based compensation			129	55,866
Employee tax withholdings by settlement of net share transactions			(41)	(13,862)
Adjustments to Additional Paid in Capital, Fair Value				25,369
Shares Issued to plans					(526)	526
Distributions and forfeitures					1,834	(1,834)
Net Income Attributable to Legg Mason, Inc.		187,208					187,208
Dividends declared							(109,968)
Vesting/Change in Estimated Redemption Value							(15,753)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax		73						3,761
Foreign currency translation adjustment		3,761						73
Ending Balance at Dec. 31, 2019		3,835,277
Stockholders' Equity Attributable to Parent, End of Period at Dec. 31, 2019		3,804,712	8,682	2,119,181	(20,108)	20,108	$ 1,804,251	(127,402)
Stockholders' Equity Attributable to Noncontrolling Interest, End of Period at Dec. 31, 2019										30,565
Common Stock, Dividends, Per Share, Declared							$ 1.20
Stockholders' Equity Attributable to Parent, Beginning of Period at Sep. 30, 2019			8,678	2,103,791	(20,003)	20,003	$ 1,777,014	(170,161)
Stockholders' Equity Attributable to Noncontrolling Interest, Beginning of Period at Sep. 30, 2019										29,803
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest									$ 1,962	1,962
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders										(1,200)
Stock Issued During Period, Value, Stock Options Exercised			1
Stock options exercised				309
Deferred compensation employee stock trust			0	181
Stock-based compensation			3	15,359
Employee tax withholdings by settlement of net share transactions			0	(459)
Adjustments to Additional Paid in Capital, Fair Value				0
Shares Issued to plans					(181)	181
Distributions and forfeitures					76	(76)
Net Income Attributable to Legg Mason, Inc.		74,775					74,775
Dividends declared							(36,179)
Vesting/Change in Estimated Redemption Value							(11,359)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax		(1,174)						43,933
Foreign currency translation adjustment		43,933						(1,174)
Ending Balance at Dec. 31, 2019		3,835,277
Stockholders' Equity Attributable to Parent, End of Period at Dec. 31, 2019		$ 3,804,712	$ 8,682	$ 2,119,181	$ (20,108)	$ 20,108	$ 1,804,251	$ (127,402)
Stockholders' Equity Attributable to Noncontrolling Interest, End of Period at Dec. 31, 2019										$ 30,565
Common Stock, Dividends, Per Share, Declared							$ 0.40

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Adjustments to reconcile Net Income to net cash used in operations:
Other Tax Expense (Benefit)	$ 2,164	$ 700
CASH FLOWS FROM FINANCING ACTIVITIES
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(22,775)	(25,538)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	(8,789)	(15,547)
Proceeds from (Payments to) Noncontrolling Interests	(31,307)	(36,328)
Cash Acquired from Acquisition	992
Proceeds from Income Tax Refunds	3,736	251
Consolidated Legg Mason, Inc.
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income	229,103	(46,952)
Adjustments to reconcile Net Income to net cash used in operations:
Depreciation and amortization	51,000	54,031
Accretion and amortization of securities discounts and premiums, net	921	1,591
Stock-based compensation	57,949	49,975
Deferred income taxes	71,648	(19,634)
Contingent consideration fair value adjustments	(1,165)	571
Other	629	286
Decrease (increase) in assets:
Investment advisory and related fees receivable	(35,807)	38,170
Net (purchases) sales of trading and other current investments	(12,316)	20,375
Other receivables	(13,744)	(16,555)
Increase (decrease) in liabilities:
Accrued compensation	20,084	51,796
Deferred compensation	19,271	(10,464)
Accounts payable and accrued expenses	(25,259)	31,130
CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES	377,084	443,989
CASH FLOWS FROM INVESTING ACTIVITIES
Payments to Acquire Businesses, Net of Cash Acquired	(10,247)	0
Payments for fixed assets	(23,209)	(38,062)
CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES	(39,079)	(26,928)
CASH FLOWS FROM FINANCING ACTIVITIES
Dividends paid	(102,044)	(84,630)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(27,906)	(32,358)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	(10,547)	(16,528)
Employee Tax Withholdings Related to net share transaction	(13,903)	(15,547)
Issuance of common stock for stock-based compensation	12,175	6,029
CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES	(425,110)	(309,181)
Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	(12,871)	(16,470)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	(99,975)	91,410
Cash, Cash Equivalents, and Restricted Cash, Beginning of Period	950,795	773,765
Cash, Cash Equivalents, and Restricted Cash, End of Period	850,820	865,175
Income Taxes Paid, Net	14,664	30,542
Interest Paid, Including Capitalized Interest, Operating and Investing Activities	67,718	69,748
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income	220,097	(47,988)
Adjustments to reconcile Net Income to net cash used in operations:
Net unrealized losses (gains) on investments	(20,816)	40,446
Net losses (gains) on investments	(9,739)	(36,495)
Decrease (increase) in assets:
Other assets	229	(6,282)
Increase (decrease) in liabilities:
Other liabilities	9,510	(83,376)
CASH FLOWS FROM INVESTING ACTIVITIES
Proceeds from Sale, Maturity and Collection of Investments	7,170	10,211
CASH FLOWS FROM FINANCING ACTIVITIES
Cash and Cash Equivalents	823,665	835,168
Restricted Cash and Cash Equivalents, Current	17,666	22,336
Restricted Cash and Cash Equivalents, Noncurrent	2,169	4,143
Consolidated Investment Vehicles [Member]
Adjustments to reconcile Net Income to net cash used in operations:
Net losses (gains) on investments	(14,904)	(1,954)
Decrease (increase) in assets:
Other assets	54,869	(751)
Increase (decrease) in liabilities:
Other liabilities	(4,379)	10,717
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from (Payments to) Noncontrolling Interests	(32,635)	(36,328)
Cash and Cash Equivalents	7,320	3,528
Consolidated Legg Mason, Inc.
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income	229,103	(46,952)
Adjustments to reconcile Net Income to net cash used in operations:
Contingent consideration fair value adjustments	(1,165)	571
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)		365,200
CASH FLOWS FROM INVESTING ACTIVITIES
Proceeds from Sales of Business, Affiliate and Productive Assets	0	923
Other Payments to Acquire Businesses	(12,793)	0
CASH FLOWS FROM FINANCING ACTIVITIES
Repayments of Debt	(250,000)	0
QS Investors [Domain]
CASH FLOWS FROM FINANCING ACTIVITIES
Payment for Contingent Consideration Liability, Financing Activities	(250)	(4,319)
Short-term Debt [Member] \| Consolidated Legg Mason, Inc.
CASH FLOWS FROM FINANCING ACTIVITIES
Repayments of Debt	$ 0	$ (125,500)

Interim Basis of Accounting Int

Interim Basis of Accounting Interim Basis of Accounting	9 Months Ended
Interim Basis of Accounting Interim Basis of Accounting	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Business Description and Basis of Presentation [Text Block]	Interim Basis of Reporting The accompanying unaudited interim consolidated financial statements of Legg Mason, Inc. and its subsidiaries (collectively “Legg Mason”) have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and the applicable rules and regulations of the Securities and Exchange Commission (the "SEC"). The interim consolidated financial statements have been prepared using the interim basis of reporting and, as such, reflect all adjustments (consisting only of normal recurring adjustments) which are, in the opinion of management, necessary for a fair statement of the results for the periods presented. The preparation of interim consolidated financial statements requires management to make assumptions and estimates that affect the amounts reported in the interim consolidated financial statements and accompanying notes. Actual amounts could differ from those estimates and the differences could have a material impact on the interim consolidated financial statements. Terms such as “we,” “us,” “our,” and “Company” refer to Legg Mason. The nature of Legg Mason's business is such that the results of any interim period are not necessarily indicative of the results of a full year. Certain disclosures included in the Company's annual report are not required to be included on an interim basis in the Company's Quarterly Reports on Form 10-Q. The Company has condensed or omitted these disclosures. Certain amounts in prior period financial statements have been reclassified to conform to the current period presentation. The information contained in the interim consolidated financial statements should be read in conjunction with the consolidated financial statements contained within Legg Mason's latest Annual Report on Form 10-K filed with the SEC.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
Significant Accounting Policies	Dec. 31, 2019
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Leases Effective April 1, 2019 Legg Mason adopted updated accounting guidance on leases which requires right-of-use ("ROU") assets and lease liabilities to be recorded on the balance sheet for leases. The guidance specifies that at the inception of a contract, an entity must determine whether the contract is or contains a lease. The contract is or contains a lease if the contract conveys the right to control the use of the property, plant, or equipment for a designated term in exchange for consideration. Legg Mason’s evaluation of its contracts to determine whether they are or contain a lease involves assessing whether there is a right to obtain substantially all of the economic benefits from the use and the right to direct the use of the identified asset in the contract. Legg Mason adopted the guidance on a modified retrospective basis as of April 1, 2019, such that related amounts in prior periods have not been restated. Legg Mason has operating leases that primarily relate to real property and financing leases that relate to equipment. As a practical expedient, Legg Mason has elected to not capitalize leases with a term of 12 months or less without a purchase option that it is likely to exercise. Also as a practical expedient for disclosure, Legg Mason has elected to not separate lease and non-lease components on operating and financing leases. Lease components are payment items directly attributable to the use of the underlying asset, while non-lease components are explicit elements of a contract not directly related to the use of the underlying asset, including pass through operating expenses such as common area maintenance, real estate taxes and utilities. ROU assets and lease liabilities are recognized on the consolidated balance sheet at the present value of the future lease payments over the life of the lease term. As implicit rates for leases are not determinable, the Company uses discount rates based on incremental borrowing rates, on a collateralized basis, for the respective underlying assets, for terms similar to the respective leases. Lease costs are included as Occupancy expense in the Consolidated Statements of Income (Loss). Fixed base payments on operating leases paid directly to the lessor are recorded as lease expense on a straight-line basis. Related variable payments based on usage, changes in an index or market rate are expensed as incurred. Payments on financing leases are recorded as lease expense on a level-yield basis. Upon adoption on April 1, 2019, Legg Mason recorded ROU assets of $342,418 and lease liabilities of $411,115 related to its real property operating leases and equipment financing leases. As further discussed in Note 8 , Legg Mason has subleased or has vacated and is pursuing subleases for certain office space. As of March 31, 2019, the lease reserve liability for subleased space and vacated space for which subleases were being pursued of $24,063 was included in other current and non-current liabilities on the Consolidated Balance Sheet under prior accounting guidance. Upon adoption of the updated guidance, the existing lease reserve liability was reclassified as a reduction of the ROU assets. ROU assets are tested for impairment when circumstances indicate that the carrying values may not be recoverable. The adoption of this guidance did not require a cumulative effect adjustment or have a material impact on the Consolidated Statements of Income (Loss) or Consolidated Statements of Cash Flows. See Note 8 for additional information. Income Taxes During the three months ended December 31, 2018, discrete tax expenses of approximately $14,100 related to uncertain federal, state and local tax positions (including those related to the Tax Cuts and Jobs Act of 2017), along with approximately $700 of other discrete tax expenses, reduced the effective income tax rate by 5.5 percentage points for the three months ended December 31, 2018. Also, during the three months ended September 30, 2018 and June 30, 2018, tax benefits totaling $2,800 related to the completion of a prior year tax audit along with $1,100 related to other discrete expenses were recognized. Together, the net impact of these discrete tax items reduced the effective income tax rate by 27.4 percentage points for the nine months ended December 31, 2018. Recent Accounting Developments In January 2017, the Financial Accounting Standards Board ("FASB") updated guidance to simplify the test for goodwill impairment. The updated guidance still requires entities to perform annual goodwill impairment tests by comparing the fair value of a reporting unit with its related carrying amount, but it eliminates the requirement to potentially calculate the implied fair value of goodwill to determine the amount of impairment, if any. Under the new guidance, an entity should recognize an impairment charge if the reporting unit's carrying amount exceeds the reporting unit’s fair value, in the amount of such excess. The guidance will be effective in fiscal 2021, unless adopted earlier. Legg Mason is evaluating its adoption. In August 2018, the FASB updated the guidance to clarify accounting for implementation costs incurred for a cloud computing arrangement that is a service contract. The update conforms the requirements for capitalizing implementation costs incurred in a cloud computing arrangement that is a service contract with the accounting guidance that provides for capitalization of costs incurred to develop or obtain internal-use-software. The updated guidance is effective for Legg Mason in fiscal 2021, unless adopted earlier. Legg Mason is evaluating its adoption. In August 2018, the FASB also updated the guidance for fair value measurements. The updated guidance modifies disclosure requirements based on the revised FASB Conceptual Framework for Financial Reporting finalized in August 2018 to improve effectiveness of financial statement disclosures. The updated guidance will be effective in fiscal 2021, unless adopted earlier. Legg Mason is evaluating its adoption.

Fair Values of Assets and Liabi

Fair Values of Assets and Liabilities	9 Months Ended
Fair Values of Assets and Liabilities	Dec. 31, 2019
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Disclosures [Text Block]	Investments and Fair Value of Assets and Liabilities The disclosures below include details of Legg Mason's financial assets and financial liabilities that are measured at fair value and net asset value ("NAV"), excluding the financial assets and financial liabilities of consolidated investment vehicles ("CIVs"). See Note 16 , Variable Interest Entities and Consolidation of Investment Vehicles, for information related to the assets and liabilities of CIVs that are measured at fair value or NAV. The fair values of financial assets and (liabilities) of the Company were determined using the following categories of inputs: As of December 31, 2019 Quoted prices in active markets Significant other observable inputs Significant unobservable inputs Investments measured at NAV Total Assets: Cash equivalents (1) $ 429,557 $ 13,098 $ — $ — $ 442,655 Equity investments: (2) Seed capital investments 73,738 29,352 21,546 1,650 126,286 Investments related to long-term incentive plans 258,040 — — — 258,040 Other investments 14,965 2,027 — — 16,992 Equity method investments: (3) Seed capital investments (4) — — 43,340 12,035 55,375 Investments related to long-term incentive plans (2) — — — 7,625 7,625 Other investments (4) — — 53 9,533 9,586 Adjusted cost investments (4) — 73 26,366 — 26,439 Derivative assets (5) 3,074 — — — 3,074 Total $ 779,374 $ 44,550 $ 91,305 $ 30,843 $ 946,072 Liabilities: Contingent consideration liabilities (6) $ — $ — $ (3,376 ) $ — $ (3,376 ) Derivative liabilities (5) (1,362 ) — — — (1,362 ) Total $ (1,362 ) $ — $ (3,376 ) $ — $ (4,738 ) As of March 31, 2019 Quoted prices in active markets Significant other observable inputs Significant unobservable inputs Investments measured at NAV Total Assets: Cash equivalents (1) $ 556,231 $ 20,160 $ — $ — $ 576,391 Equity investments: (2) Seed capital investments 98,276 30,601 1,455 2,183 132,515 Investments related to long-term incentive plans 211,802 — — — 211,802 Other investments 19,486 2,142 — — 21,628 Equity method investments: (3) Seed capital investments (4) — — 40,854 10,675 51,529 Investments related to long-term incentive plans (2) — — — 11,184 11,184 Other investments (4) — — 1,218 10,251 11,469 Adjusted cost investments (4) — 74 12,171 — 12,245 Derivative assets (5) 4,183 — — — 4,183 Total $ 889,978 $ 52,977 $ 55,698 $ 34,293 $ 1,032,946 Liabilities: Contingent consideration liabilities (6) $ — $ — $ (1,415 ) $ — $ (1,415 ) Derivative liabilities (5) (7,579 ) — — — (7,579 ) Total $ (7,579 ) $ — $ (1,415 ) $ — $ (8,994 ) (1) Cash investments in actively traded money market funds are classified as Level 1. Cash investments in time deposits and other are measured at amortized cost, which approximates fair value because of the short time between purchase of the instrument and its expected realization and are classified as Level 2. (2) Included in Investment securities on the Consolidated Balance Sheets. (3) Primarily investments in private equity and real estate funds. These equity method investments are investment companies that primarily record underlying investments at fair value. Therefore, the fair value of these investments is measured using Legg Mason's share of the investee's underlying net income or loss, which is predominately representative of fair value adjustments in the investments held by the equity method investee. Other equity method investments not measured at fair value on a recurring basis of $27,051 and $28,160 as of December 31, 2019 and March 31, 2019, respectively, are excluded from the tables above. (4) Included in Other noncurrent assets in the Consolidated Balance Sheets. (5) See Note 14 . (6) See Note 9 . The net realized and unrealized gains (losses) for investment securities classified as equity investments were $25,698 and $(34,793) for the three months ended December 31, 2019 and 2018, respectively, and $30,938 and $(25,246) for the nine months ended December 31, 2019 and 2018, respectively. The net unrealized gains (losses) relating to equity investments still held as of the reporting date were $21,441 and $(38,741) for the three months ended December 31, 2019 and 2018, respectively, and $13,765 and $(51,313) for the nine months ended December 31, 2019 and 2018, respectively. Seed capital investments represent investments made by Legg Mason to fund new investment products and strategies. As of December 31, 2019 and March 31, 2019, seed capital investments totaled $220,077 and $227,756 , respectively, with investments in excess of $1,000 in 45 funds and 52 funds, respectively, comprising over 90% of the total at each period end. Seed capital investments presented in the tables above exclude $38,416 and $43,712 , as of December 31, 2019 and March 31, 2019, respectively, which is related to Legg Mason's investments in CIVs. See Note 16 for additional information regarding Legg Mason's investments in CIVs. The changes in financial assets and (liabilities) measured at fair value using significant unobservable inputs (Level 3) are presented in the tables below: Balance as of September 30, 2019 Purchases Sales Redemptions/ Settlements/ Other Transfers Realized and unrealized gains/(losses), net Balance as of December 31, 2019 Assets: Equity investments - seed capital $ 20,200 $ 1,000 — — — 346 21,546 Equity method investments: Seed capital investments 43,252 283 — (2,073 ) — 1,878 43,340 Other 1,297 — — (1,209 ) — (35 ) 53 Adjusted cost investments 22,869 3,497 — — — — 26,366 $ 87,618 $ 3,780 $ — $ (3,282 ) $ — $ 1,843 $ 91,305 Liabilities: Contingent consideration liabilities $ (3,625 ) $ — n/a $ 250 n/a $ (1 ) $ (3,376 ) Balance as of September 30, 2018 Purchases Sales Redemptions/ Settlements/ Other Transfers Realized and unrealized gains/(losses), net Balance as of December 31, 2018 Assets: Equity investments - seed capital $ 1,394 $ — $ — $ — $ — $ (128 ) $ 1,266 Equity method investments: Seed capital investments 37,020 5,516 — (1,880 ) — 398 41,054 Other 1,840 — — (19 ) — — 1,821 Adjusted cost investments 10,906 1,063 — — — 3 11,972 $ 51,160 $ 6,579 $ — $ (1,899 ) $ — $ 273 $ 56,113 Liabilities: Contingent consideration liabilities $ (1,900 ) $ — n/a $ — n/a $ — $ (1,900 ) Balance Purchases Sales Redemptions/ Settlements/ Other Transfers Realized and unrealized gains/(losses), net Balance Assets: Equity Investments - seed capital $ 1,455 $ 21,200 $ — $ (1,457 ) $ — $ 348 $ 21,546 Equity method investments: Seed capital investments 40,854 2,621 — (3,045 ) — 2,910 43,340 Other 1,218 — — (1,222 ) — 57 53 Adjusted cost investments 12,171 14,318 — (125 ) — 2 26,366 $ 55,698 $ 38,139 $ — $ (5,849 ) $ — $ 3,317 $ 91,305 Liabilities: Contingent consideration liabilities $ (1,415 ) (3,389 ) n/a $ 250 n/a $ 1,178 $ (3,376 ) Balance Purchases Sales Redemptions/ Settlements/ Other Transfers Realized and unrealized gains/(losses), net Balance Assets: Equity Investments - seed capital $ 1,242 $ — $ — $ — $ — $ 24 $ 1,266 Equity method investments: Seed capital investments 33,725 9,483 — (4,280 ) — 2,126 41,054 Other — 1,650 — (19 ) — 190 1,821 Adjusted cost investments 6,951 5,063 — (2 ) — (40 ) 11,972 $ 41,918 $ 16,196 $ — $ (4,301 ) $ — $ 2,300 $ 56,113 Liabilities: Contingent consideration liabilities $ (5,607 ) $ — n/a $ 4,319 n/a $ (612 ) $ (1,900 ) Realized and unrealized gains and losses recorded for Level 3 investments are included in Other non-operating income (expense), net, in the Consolidated Statements of Income (Loss). The change in unrealized gains for Level 3 investments and liabilities still held at the reporting date was $1,776 and $275 for the three months ended December 31, 2019 and 2018, respectively, and $4,089 and $2,336 for the nine months ended December 31, 2019 and 2018, respectively. Level 3 purchases for the nine months ended December 31, 2019 reflect a seed capital investment in a real estate-focused fund designed for individual investors and an adjusted cost minority investment in a U.K. retirement solutions provider. There were no significant transfers between Level 1 and Level 2 during the three or nine months ended December 31, 2019 and 2018. As a practical expedient, Legg Mason relies on the NAV of certain investments as their fair value. The NAVs that have been provided by the investees have been derived from the fair values of the underlying investments as of the respective reporting dates. The following table summarizes the nature of these investments and any related liquidation restrictions or other factors which may impact the ultimate value realized: Fair Value Determined Using NAV As of December 31, 2019 Category of Investment Investment Strategy December 31, 2019 March 31, 2019 Unfunded Commitments Remaining Term Funds-of-hedge funds Global macro, fixed income, long/short equity, natural resources, systematic, emerging market, European hedge $ 11,905 (1) $ 9,910 n/a n/a Hedge funds Fixed income - developed market, event driven, fixed income - hedge, relative value arbitrage, European hedge 1,049 1,515 n/a n/a Private equity funds Long/short equity 10,244 (2) 11,636 $ 5,698 Up to 10 years Equity method investments related to long-term incentive plans Alternatives, structured securities, short-dated fixed income 7,625 (2) 11,185 n/a n/a Other Various 20 47 n/a Various Total $ 30,843 $ 34,293 $ 5,698 n/a - not applicable (1) Liquidation restrictions: 14% monthly redemption, 1% quarterly redemption, and 85% are not subject to redemption or are not currently redeemable. (2) Liquidations are expected over the remaining term. There are no current plans to sell any of these investments held as of December 31, 2019.

Acquisitions (Notes)

Acquisitions (Notes)	9 Months Ended
Acquisitions (Notes)	Dec. 31, 2019
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	Acquisition On April 10, 2019, Clarion Partners acquired a majority stake in Gramercy Europe (Jersey) Limited ("Gramercy"), a European real estate investment business specializing in pan-European logistics and industrial assets. The transaction required an initial cash payment of $10,247 (net of cash acquired), which was paid by Clarion Partners using existing cash resources, and a potential contingent consideration payment of up to approximately $3,735 (using the foreign exchange rate as of April 10, 2019, for the €3,315 potential payment), due on the fifth anniversary of closing upon the achievement of certain financial metrics. In connection with the acquisition, Clarion Partners recognized an amortizable intangible asset management contracts asset of $5,876 , with a useful life of eight years at acquisition, goodwill of $20,196 , and noncontrolling interest of $11,715 . The fair value of the contingent consideration at acquisition was $3,389 .

Fixed Assets

Fixed Assets	9 Months Ended
Fixed Assets	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Fixed Assets	Fixed Assets The following table reflects the components of fixed assets as of: December 31, 2019 March 31, 2019 Software $ 276,096 $ 269,944 Leasehold improvements 213,439 212,742 Equipment 162,795 159,421 Total cost 652,330 642,107 Less: accumulated depreciation and amortization (513,495 ) (492,118 ) Fixed assets, net $ 138,835 $ 149,989 Depreciation and amortization expense related to fixed assets was $12,252 and $11,799 for the three months ended December 31, 2019 and 2018, respectively, and $34,098 and $35,659 for the nine months ended December 31, 2019 and 2018, respectively.

Intangible Assets and Goodwill

Intangible Assets and Goodwill	9 Months Ended
Intangible Assets and Goodwill	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets and Goodwill	Intangible Assets and Goodwill The following table reflects the components of intangible assets as of: December 31, 2019 March 31, 2019 Amortizable intangible asset management contracts and other Cost $ 372,808 $ 366,930 Accumulated amortization (257,410 ) (240,488 ) Net (1) 115,398 126,442 Indefinite–life intangible assets U.S. domestic mutual fund management contracts 2,106,351 2,106,351 Clarion Partners fund management contracts 505,200 505,200 EnTrust Global fund management contracts 126,804 126,804 Other fund management contracts 475,069 473,360 Trade names 48,695 48,602 3,262,119 3,260,317 Intangible assets, net $ 3,377,517 $ 3,386,759 (1) As of December 31, 2019, includes $5,305 related to the acquisition of Gramercy by Clarion Partners. See Note 4 for additional information. Certain of Legg Mason's intangible assets are denominated in currencies other than the U.S. dollar and balances related to these assets will fluctuate with changes in the related foreign currency exchange rates. Indefinite-life Intangible Assets and Goodwill Legg Mason performed its annual impairment testing of goodwill and indefinite-life intangible assets as of October 31, 2019, and determined that there was no impairment in the value of these assets. As a result of uncertainty regarding future market conditions and economic results, assessing the fair value of the reporting unit and intangible assets requires management to exercise significant judgment. Legg Mason's goodwill impairment testing noted the assessed fair value of the Global Asset Management business reporting unit exceeded its related carrying value by 22% . The assessed fair values of the EnTrust Global indefinite-life fund management contracts and trade name assets exceeded their respective carrying values of $126,804 and $10,300 by 10% and 6% , respectively. Should market performance, flows, and/or related assets under management ("AUM") levels decrease in the near term, or other factors change, such that cash flow projections deviate from current projections, it is reasonably possible that these assets could become impaired, and the impairment could be a material amount. Legg Mason also determined that no triggering events occurred as of December 31, 2019 that would require further impairment testing. Legg Mason's annual impairment testing process in the prior fiscal year determined that the carrying values of the EnTrust Global indefinite-life fund management contracts and trade name assets, and the RARE Infrastructure indefinite-life fund management contracts and trade name assets, exceeded their respective fair values, which resulted in impairment charges totaling $358,800 in the quarter ended December 31, 2018. The impairment charges at EnTrust Global in the prior year were primarily the result of continued net client outflows from legacy high net worth fund-of-fund products leading to reduced growth expectations in both management fees and performance fees, a declining margin, and a higher discount rate. These changes resulted in a reduction of the projected cash flows and Legg Mason’s overall assessment of fair value of the assets, such that the carrying values of the EnTrust Global fund management contracts intangible asset of $401,404 and trade name asset of $28,500 were impaired by $274,600 and $18,200 , respectively. Management estimated the fair values of these assets based upon discounted cash flow analyses, as well as a relief from royalty method for the trade name asset, using unobservable market inputs, which are Level 3 measurements. The significant assumptions used in the cash flow analyses included projected revenue growth rates, discount rates, and royalty rates. Base revenues related to the EnTrust Global fund management contracts were assumed to have annual growth (contraction) rates ranging from (19.4)% to 3.9% (average: 3.0% ), and the projected cash flows from the EnTrust Global fund management contracts were discounted at 17% . Base revenues related to the EnTrust Global trade name asset were assumed to have annual growth rates ranging from 0.0% to 4.6% (average: 3.9% ), a royalty rate of 1.0% , and a discount rate of 16.5% . The impairment charges at RARE Infrastructure in the prior year were primarily the result of lower than expected net client inflows and performance fees, leading to a lower margin, and a higher discount rate. These changes resulted in a reduction of the related projected cash flows and Legg Mason’s overall assessment of fair value of the assets, such that the RARE Infrastructure fund management contracts asset carrying value of approximately $120,800 and trade name asset carrying value of $2,800 were impaired by $65,000 and $1,000 , respectively. Management estimated the fair values of these assets based upon discounted cash flow analyses, as well as a relief from royalty method for the trade name asset, using unobservable market inputs, which are Level 3 measurements. The significant assumptions used in the cash flow analyses included projected revenue growth rates, discount rates, and royalty rates. Base revenues related to the RARE Infrastructure fund management contracts were assumed to have annual growth rates ranging from 4.4% to 4.9% (average: 4.8% ), and the projected cash flows from the RARE Infrastructure fund management contracts were discounted at 16.5% . Base revenues related to the RARE Infrastructure trade name asset were assumed to have annual growth rates ranging from 0.9% to 4.6% (average: 4.2% ), a royalty rate of 1.0% , and a discount rate of 16.5% . The change in carrying value of goodwill is summarized below: Gross Book Value Accumulated Impairment Net Book Value Balance as of March 31, 2019 $ 3,045,454 $ (1,161,900 ) $ 1,883,554 Impact of excess tax basis amortization (8,256 ) — (8,256 ) Changes in foreign exchange rates 603 — 603 Business acquisition (1) 20,196 — 20,196 Balance as of December 31, 2019 $ 3,057,997 $ (1,161,900 ) $ 1,896,097 (1) See Note 4 for additional information. Amortizable Intangible Asset Management Contracts and Other There were no impairments to amortizable management contract intangible assets during the three or nine months ended December 31, 2019. During the three months ended December 31, 2018, projected revenues related to the RARE Infrastructure separate account contracts asset declined due to losses of separate account clients and AUM. Based on revised attrition estimates, the remaining useful life was decreased from three and one-half to two years at December 31, 2018. As a result of the decline in projected revenues and the revised estimate of useful life, the amortized carrying value of approximately $6,900 as of December 31, 2018 was determined to exceed its fair value and an impairment charge of $6,400 was recorded during the three months ended December 31, 2018. Management estimated the fair value of this asset as of December 31, 2018, based on a discounted cash flow analysis using unobservable market inputs, which are Level 3 measurements. In addition to the useful life, other significant assumptions used in the cash flow analysis included projected revenue growth rates of 7% and a discount rate of 16.5% . As of December 31, 2019 , amortizable intangible asset management contracts and other are being amortized over a weighted-average remaining life of 5.6 years. Estimated amortization expense for each of the next five fiscal years and thereafter is as follows: Remaining fiscal 2020 $ 5,640 2021 21,834 2022 21,485 2023 20,725 2024 19,896 Thereafter 25,818 Total $ 115,398

Long-Term Debt

Long-Term Debt	9 Months Ended
Long-Term Debt	Dec. 31, 2019
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt Long-term debt, net, consists of the following: December 31, 2019 March 31, 2019 Carrying Value Unamortized Discount (Premium) Unamortized Debt Issuance Costs Maturity Amount Carrying Value 3.95% Senior Notes due July 2024 $ 248,917 $ 206 $ 877 $ 250,000 $ 248,738 4.75% Senior Notes due March 2026 447,786 — 2,214 450,000 447,521 5.625% Senior Notes due January 2044 548,079 (2,938 ) 4,859 550,000 548,020 6.375% Junior Notes due March 2056 242,614 — 7,386 250,000 242,461 5.45% Junior Notes due September 2056 485,017 — 14,983 500,000 484,711 2.7% Senior Notes due July 2019 — — — — 250,301 Subtotal 1,972,413 (2,732 ) 30,319 2,000,000 2,221,752 Less: Current portion — — — — (250,301 ) Total $ 1,972,413 $ (2,732 ) $ 30,319 $ 2,000,000 $ 1,971,451 On July 15, 2019, Legg Mason repaid the $250,000 of 2.7% Senior Notes due July 2019, using existing cash resources. The remaining $2,000,000 of long-term debt outstanding as of December 31, 2019 matures after fiscal 2024. As of December 31, 2019 , the estimated fair value of long-term debt was $2,170,660 . The fair value of debt was estimated using publicly quoted market prices and was classified as Level 2 in the fair value hierarchy.

Leases (Notes)

Leases (Notes)	9 Months Ended
Leases (Notes)	Dec. 31, 2019
Leases [Abstract]
Lessee, Operating Leases [Text Block]	Leases Legg Mason leases over 1,500 square feet of office space with approximately one-third currently subleased to various firms, the majority of which are within the U.S. Office facilities and equipment are leased under various non-cancelable operating leases and certain equipment is also leased under financing leases. Legg Mason's current leases have remaining terms that vary up to 19 years. Certain leases provide for options to extend up to 15 years and/or options to terminate within seven years . As previously disclosed in Note 2 , the lease reserve liability related to our subleased space and vacated space for which subleases are being pursued was $24,063 as of March 31, 2019. Upon adoption of the updated lease accounting guidance on April 1, 2019, the existing Other current and non-current liabilities were reclassified as a reduction of the ROU asset recorded in accordance with the updated guidance. Leases included in the Consolidated Balance Sheets were as follows: Classification As of December 31, 2019 Operating leases: Operating lease ROU assets Right-of-use assets $ 294,174 Operating lease liabilities Lease liabilities 361,921 Finance leases: Property and equipment, gross Right-of-use assets $ 2,134 Less: accumulated depreciation Right-of-use assets (643 ) Property and equipment, net $ 1,491 Finance lease liabilities Lease liabilities $ 1,367 The components of lease expense included in the Consolidated Statement of Income (Loss) were as follows: Classification Three Months Ended December 31, 2019 Nine Months Ended December 31, 2019 Operating lease cost Occupancy expense $ 25,361 $ 67,172 Financing lease cost: Amortization of right-of-use asset Occupancy expense 251 737 Interest on lease liabilities Interest expense 11 36 Total finance lease cost 262 773 Short-term lease cost Occupancy expense 1,190 4,885 Variable lease cost (1) Occupancy expense 6,599 17,788 Less: sublease billings Occupancy expense (6,091 ) (18,624 ) Net lease cost (2) $ 27,321 $ 71,994 (1) Variable lease cost includes operating expenses, real estate and other taxes. Variable lease costs are determined by whether they are to be included in base rent and if amounts are based on a consumer price index. (2) Excludes other occupancy expense of $5,292 and $13,123 for the three and nine months ended December 31, 2019, respectively, related to leasehold amortization. During the quarter ended December 31, 2019, in connection with Legg Mason's strategic restructuring, as further discussed in Note 15, it was determined that the carrying values of certain right-of-use assets would not be recoverable. Related impairment charges of $4,328 (exclusive of accelerated depreciation of $ 1,603 ) were recognized in the three months ended December 31, 2019, and are included in operating lease cost in the table above and in Occupancy expense in the Consolidated Statement of Income (Loss). The fair value of the right-of-use asset related to a substantial portion of the charge was estimated based on various assumptions, including the prevailing rental rates in the applicable market and the amount of time it will take to secure a sublease agreement. Lease expense incurred in the three and nine months ended December 31, 2018 was $20,445 and $64,649 , respectively, excluding leasehold amortization of $3,632 and $11,684 , respectively. Sublease amounts billed are recorded as a reduction of Occupancy expense in the Consolidated Statement of Income (Loss). The amounts billed are primarily fixed base rental payments combined with variable lease cost reimbursements. Sublease amounts related to base rent are recorded on a straight-line basis. As of December 31, 2019, undiscounted future cash flows for each of the next five fiscal years and thereafter related to operating and finance leases were as follows: Operating Leases Finance Leases Total Remaining fiscal 2020 $ 23,181 $ 263 $ 23,444 2021 88,048 714 88,762 2022 86,385 271 86,656 2023 84,530 131 84,661 2024 70,210 35 70,245 Thereafter 46,472 5 46,477 Total lease payments 398,826 1,419 400,245 Less: Imputed interest (36,905 ) (52 ) (36,957 ) Present value of lease liabilities $ 361,921 $ 1,367 $ 363,288 As of December 31, 2019, the weighted-average remaining lease terms and weighted-average discount rates for operating and finance leases were as follows: Operating Leases Finance Leases Weighted-average remaining lease term (in years) 4.8 2.0 Weighted-average discount rates 4.0 % 3.1 % Supplemental cash flow information related to leases was as follows: Nine Months Ended December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 64,470 Financing cash flows from finance leases 727 There was no significant non-cash lease activity for the nine months ended December 31, 2019. As of March 31, 2019, minimum aggregate rentals under operating leases were as follows: Operating Leases (1) 2020 $ 90,667 2021 86,095 2022 84,485 2023 83,425 2024 72,192 Thereafter 47,240 Total $ 464,104 (1) The minimum rental commitments have not been reduced by $105,193 for minimum sublease rentals to be received under non-cancelable subleases.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies As of December 31, 2019 , Legg Mason had commitments to invest $17,588 in limited partnerships that make private investments. These commitments are expected to be outstanding, or funded as required, through the end of their respective investment periods ranging through fiscal 2030. Also, in connection with the acquisition of Clarion Partners in April 2016, Legg Mason committed to ultimately provide $100,000 of seed capital to Clarion Partners products. As of December 31, 2019, Legg Mason also had future commitments totaling $102,794 related to multi-year agreements for certain services, of which $20,087 , $39,348 and $21,534 will be due during the remainder of fiscal 2020, and in fiscal 2021 and fiscal 2022, respectively. The remaining $21,825 is due through fiscal 2027. In the normal course of business, Legg Mason enters into contracts that contain a variety of representations and warranties and that provide general indemnifications, which are not considered financial guarantees by relevant accounting guidance. Legg Mason’s maximum exposure under these arrangements is unknown, as this would involve future claims that may be made against Legg Mason that have not yet occurred. Legg Mason has been the subject of customer complaints and has also been named as a defendant in various legal actions arising primarily from asset management, securities brokerage, and investment banking activities, including certain class actions, which primarily allege violations of securities laws and seek unspecified damages, which could be substantial. In the normal course of its business, Legg Mason has also received subpoenas and is currently involved in other governmental and industry self-regulatory agency inquiries, investigations and, from time to time, proceedings involving asset management activities. In accordance with guidance for accounting for contingencies, Legg Mason has established provisions for estimated losses from pending complaints, legal actions, investigations and proceedings when it is probable that a loss has been incurred and a reasonable estimate of loss can be made. There are matters of litigation and other proceedings, including those described above as customer complaints, legal actions, inquiries, proceedings and investigations, where Legg Mason cannot estimate the reasonably possible loss or range of loss. The inability to provide a reasonably possible amount or range of losses is not because there is uncertainty as to the ultimate outcome of a matter, but because liability and damage issues have not developed to the point where Legg Mason can conclude that there is both a reasonable possibility of a loss and a meaningful amount or range of possible losses. There are numerous aspects to customer complaints, legal actions, inquiries, proceedings and investigations that prevent Legg Mason from estimating a related amount or range of reasonably possible losses. These aspects include, among other things, the nature of the matters; that significant relevant facts are not known, are uncertain or are in dispute; and that damages sought are not specified, are uncertain, unsupportable or unexplained. In addition, for legal actions, discovery may not yet have started, may not be complete or may not be conclusive, and meaningful settlement discussions may not have occurred. Further, for regulatory matters, investigations may run their course without any clear indication of wrongdoing or fault until their conclusion. In management's opinion, an adequate accrual has been made as of December 31, 2019 , to provide for any probable losses that may arise from matters for which the Company could reasonably estimate an amount. Legg Mason's financial condition, results of operations and cash flows could be materially affected during a period in which probable losses become apparent or a matter is ultimately resolved. In addition, the ultimate costs of litigation-related charges can vary significantly from period-to-period, depending on factors such as market conditions, the size and volume of customer complaints and claims, including class action suits, and recoveries from indemnification, contribution, insurance reimbursement, or reductions in compensation under revenue share arrangements. Noncontrolling Interests Legg Mason may be obligated to settle redeemable noncontrolling interests related to certain affiliates. As of December 31, 2019 , affiliate redeemable noncontrolling interests, excluding amounts related to management equity plans, aggregated $524,889 . In addition, as of December 31, 2019 , the estimated redemption fair value for units under affiliate management equity plans (redeemable and nonredeemable) aggregated $82,495 . See Notes 10 and 13 for additional information regarding affiliate management equity plans and noncontrolling interests, respectively. Contingent Consideration As further discussed in Note 4 , on April 10, 2019, Clarion Partners acquired a majority interest in Gramercy. The transaction included a potential contingent consideration payment of up to $3,721 (using the foreign exchange rate as of December 31, 2019, for the €3,315 potential payment), due on the fifth anniversary of closing upon the achievement of certain financial metrics. As of December 31, 2019 and March 31, 2019, contingent consideration liabilities totaling $3,376 and $1,415 , respectively, were included in Other non-current liabilities in the Consolidated Balance Sheets.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
Stock-Based Compensation	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation Legg Mason's stock-based compensation includes restricted stock units, stock options, an employee stock purchase plan, market and performance-based performance shares payable in common stock, affiliate management equity plans and deferred compensation payable in stock. Shares available for issuance under the equity incentive stock plan as of December 31, 2019 , were 6,292 . Options under Legg Mason’s equity incentive stock plans have been granted at prices not less than 100% of the fair market value on the date of grant. Options are generally exercisable in equal increments over four years and expire within eight years to 10 years from the date of grant. The components of Legg Mason's total stock-based compensation expense were as follows: Three Months Ended December 31, Nine Months Ended December 31, 2019 2018 2019 2018 Restricted stock and restricted stock units $ 12,025 $ 11,668 $ 43,507 $ 38,707 Stock options 728 1,057 2,643 3,513 Employee stock purchase plan 77 96 415 480 Non-employee director awards — — 1,000 1,025 Affiliate management equity plans 23 719 1,670 2,213 Performance share units 2,564 1,202 8,688 4,014 Employee stock trust 9 8 26 23 Total stock-based compensation expense $ 15,426 $ 14,750 $ 57,949 $ 49,975 Restricted Stock Restricted stock and restricted stock unit transactions are summarized below: Nine Months Ended December 31, 2019 2018 Number of Shares Weighted-Average Grant Date Value Number of Shares Weighted-Average Grant Date Value Unvested shares at March 31 3,045 $ 37.76 3,299 $ 38.09 Granted 1,205 35.50 1,179 39.05 Vested (1,288 ) 38.70 (1,286 ) 39.73 Canceled/forfeited (59 ) 36.88 (108 ) 37.62 Unvested shares at December 31 2,903 $ 36.43 3,084 $ 37.80 Unamortized compensation cost related to unvested restricted stock awards at December 31, 2019, of $63,186 is expected to be recognized over a weighted-average period of 1.6 years . Stock Options Stock option transactions under Legg Mason's equity incentive plans are summarized below: Nine Months Ended December 31, 2019 2018 Number of Shares Weighted-Average Exercise Price Per Share Number of Shares Weighted-Average Exercise Price Per Share Options outstanding at March 31 4,115 $ 39.05 4,437 $ 38.78 Exercised (369 ) 31.55 (189 ) 31.62 Canceled/forfeited (80 ) 46.18 (95 ) 43.92 Options outstanding at December 31 3,666 $ 39.65 4,153 $ 38.99 At December 31, 2019, options were exercisable for 3,262 shares, with a weighted-average exercise price of $40.23 and a weighted average remaining contractual life of 3.0 years. Unamortized compensation cost related to unvested options for 404 shares at December 31, 2019, was $920 , which is expected to be recognized over a weighted-average period of 0.9 years . Affiliate Management Equity Plans In connection with the acquisition of Clarion Partners in April 2016, Legg Mason implemented a management equity plan for Clarion Partners that entitles certain of its key employees to participate in 15% of the future growth, if any, of the Clarion Partners enterprise value (subject to appropriate discounts) subsequent to the date of the grant. As of December 31, 2019 , the estimated aggregate redemption fair value of units under the plan, as if they were currently redeemable, was $12,100 . Effective March 1, 2016, Legg Mason implemented a management equity plan for Royce Investment Partners ("Royce") key employees. Under the management equity plan, minority equity interests equivalent to a 24.5% interest in the Royce entity have been issued to certain key employees. Equity holders receive quarterly distributions of a portion of Royce's pre-tax income in amounts equal to the percentage of ownership represented by the equity they hold, subject to payment of Legg Mason's revenue share and reasonable expenses. As of December 31, 2019 , the estimated aggregate redemption fair value of units under the plan, as if they were currently redeemable, was $10,800 . On March 31, 2014, Legg Mason implemented a management equity plan and granted units to key employees of its subsidiary ClearBridge Investments, LLC ("ClearBridge") that entitle them to participate in 15% of the future growth, if any, of the ClearBridge enterprise value (subject to appropriate discounts) subsequent to the grant date. Independent valuation determined the aggregate cost of the award to be approximately $16,000 , which was recognized as Compensation and benefits expense in the Consolidated Statements of Income (Loss) over the related vesting periods through March 2019. Total compensation expense related to the ClearBridge affiliate management equity plan was $23 and $719 for the three months ended December 31, 2019 and 2018, respectively, and $1,670 and $2,213 for the nine months ended December 31, 2019 and 2018, respectively. The compensation expense for the nine months ended December 31, 2019, includes $1,600 related to the modification of the plan settlement features, which resulted in an increase in the fair value of the awards. This arrangement provides for one-half of the cost to be absorbed by the ClearBridge incentive pool. As of December 31, 2019 , the estimated aggregate redemption fair value of vested units under the ClearBridge plan, as if they were currently redeemable, was approximately $59,595 . Other As of December 31, 2019 and 2018, non-employee directors held 34 and 98 restricted stock units, respectively, which vest on the grant date and are, therefore, not included in the unvested shares of restricted stock units in the table above. Upon the acquisition of Clarion Partners in April 2016, Legg Mason granted certain key employees of Clarion Partners a total of 716 performance-based Legg Mason restricted share units, which are not included in the unvested shares of restricted stock units in the table above, with an aggregate fair value of $11,121 , which was included in the purchase price. These restricted share units vest upon Clarion Partners achieving a certain level of EBITDA, as defined in the purchase agreement, within a designated period after the closing of the acquisition. In May 2019 and 2018, Legg Mason granted certain executive officers a total of 168 and 163 performance share units, respectively, as part of their fiscal 2019 and 2018 incentive awards with an aggregate value of $ 6,334 and $5,820 , respectively. The vesting of performance share units granted in May 2019 and 2018 and the number of shares payable at vesting are determined based on Legg Mason’s relative total stockholder return and relative organic growth rate of long-term AUM over three-year periods ending March 31, 2022 and 2021, respectively. The recorded grant date fair values per performance share unit of $ 37.63 and $35.67 , respectively, were estimated based on multiple fair value Monte Carlo pricing models. Expense associated with these grants are adjusted for the level of relative organic growth expected to be ultimately achieved. The estimated fair values for the May 2019 grant range from $ 21.63 to $ 45.63 per performance share unit and for the May 2018 grant range from $18.08 to $44.46 per performance share unit. The following assumptions were used in the Monte Carlo pricing models for the May 2019 and 2018 grants: May 2019 May 2018 Expected dividend yield 4.41 % 3.49 % Risk-free interest rate 2.11 % 2.71 % Average expected volatility 23.96 % 26.14 %

Revenue Revenue

Revenue Revenue	9 Months Ended
Revenue Revenue	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Text Block]	Revenue The following table presents Total Operating Revenues disaggregated by asset class: Three Months Ended December 31, Nine Months Ended December 31 2019 2018 2019 2018 Equity $ 293,130 $ 296,738 $ 875,965 $ 931,350 Fixed Income 299,121 275,559 873,687 855,343 Alternative 139,061 110,390 384,068 361,239 Liquidity 22,602 21,635 68,818 62,722 Total Operating Revenues $ 753,914 $ 704,322 $ 2,202,538 $ 2,210,654 Revenues by geographic location are primarily based on the location of the advisor or domicile of fund families managed by Legg Mason and do not necessarily reflect where the customer resides or the currency in which the revenues are denominated. The following table presents Total Operating Revenues disaggregated by geographic location: Three Months Ended December 31, Nine Months Ended December 31, 2019 2018 2019 2018 United States $ 583,080 $ 547,696 $ 1,730,546 $ 1,711,426 United Kingdom 56,264 35,142 121,303 111,739 Other International 114,570 121,484 350,689 387,489 Total Operating Revenues $ 753,914 $ 704,322 $ 2,202,538 $ 2,210,654 Certain sales commissions paid in connection with obtaining assets managed in retail separately managed accounts are capitalized as deferred costs. As of December 31, 2019 and March 31, 2019, capitalized sales commissions of $8,565 and $8,126 , respectively, were included in Other current assets and $10,234 and $10,147 , respectively, were included in Other non-current assets in the Consolidated Balance Sheets. Amortization related to capitalized sales commissions included in Compensation and benefits in the Consolidated Statements of Income (Loss) was $2,417 and $2,305 for the three months ended December 31, 2019 and 2018, respectively, and $7,050 and $6,964 for the nine months ended December 31, 2019 and 2018, respectively. There were no impairment losses in relation to the capitalized costs during the three or nine months ended December 31, 2019 or 2018.

Earnings Per Share

Earnings Per Share	9 Months Ended
Earnings Per Share	Dec. 31, 2019
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	Earnings Per Share The following table presents the computations of basic and diluted earnings per share attributable to Legg Mason, Inc. shareholders ("EPS"): Three Months Ended December 31, Nine Months Ended December 31, 2019 2018 2019 2018 Basic weighted-average shares outstanding for EPS 86,878 85,537 86,666 85,381 Potential common shares: Dilutive employee stock options 287 — 266 — Diluted weighted-average shares outstanding for EPS 87,165 85,537 86,932 85,381 Net Income (Loss) Attributable to Legg Mason, Inc. $ 74,775 $ (216,888 ) $ 187,208 $ (77,995 ) Less: Earnings (distributed and undistributed) allocated to participating securities 2,428 1,049 6,138 3,190 Net Income (Loss) (Distributed and Undistributed) Allocated to Shareholders (Excluding Participating Securities) $ 72,347 $ (217,937 ) $ 181,070 $ (81,185 ) Net Income (Loss) per share Attributable to Legg Mason, Inc. Shareholders Basic $ 0.83 $ (2.55 ) $ 2.09 $ (0.95 ) Diluted 0.83 (2.55 ) 2.08 (0.95 ) The weighted-average shares exclude weighted-average unvested restricted shares deemed to be participating securities of 2,935 and 3,104 for the three months ended December 31, 2019 and 2018 , respectively, and 2,919 and 3,104 for the nine months ended December 31, 2019 and 2018, respectively. Options to purchase 1,860 and 1,995 shares for the three and nine months ended December 31, 2019, respectively, were not included in the computation of diluted EPS because the presumed proceeds from exercising such options, including the related unamortized expense, exceed the average price of the common shares for the period and, therefore, the options are deemed antidilutive. The diluted EPS calculation for the three and nine months ended December 31, 2018, excludes 56 and 143 potential common shares from employee stock options, respectively, that are anti-dilutive due to the net loss in each period.

Noncontrolling Interests

Noncontrolling Interests	9 Months Ended
Noncontrolling Interests	Dec. 31, 2019
Noncontrolling Interest [Abstract]
Noncontrolling Interest Disclosure [Text Block]	Noncontrolling Interests Net income attributable to noncontrolling interests included the following amounts: Three Months Ended December 31, Nine Months Ended December 31, 2019 2018 2019 2018 Net income attributable to redeemable noncontrolling interests $ 14,266 $ 8,852 $ 36,595 $ 24,460 Net income attributable to nonredeemable noncontrolling interests 1,962 1,646 5,300 6,583 Total $ 16,228 $ 10,498 $ 41,895 $ 31,043 The following tables present the changes in redeemable and nonredeemable noncontrolling interests: Redeemable noncontrolling interests Consolidated investment vehicles (1) and other Affiliate Noncontrolling interests Management equity plans Total Nonredeemable noncontrolling interests (3) Balance as of March 31, 2019 $ 103,630 $ 540,595 $ 48,151 $ 692,376 $ 29,784 Net income attributable to noncontrolling interests 9,006 27,589 — 36,595 5,300 Business acquisition 11,715 — 11,715 — Net subscriptions (redemptions) (31,307 ) — — (31,307 ) — Purchase of affiliate noncontrolling interest: Payment (fair value portion) — (8,789 ) — (8,789 ) — Change in redemption value — (25,708 ) — (25,708 ) — Distributions — (22,775 ) — (22,775 ) (4,519 ) Foreign exchange — (833 ) — (833 ) — Vesting/change in estimated redemption value — 3,095 13,984 17,079 — Balance as of December 31, 2019 $ 81,329 $ 524,889 $ 62,135 $ 668,353 $ 30,565 Redeemable noncontrolling interests Consolidated investment vehicles (1) and other Affiliate Noncontrolling interests Management equity plans Total Nonredeemable noncontrolling interests (2) Balance as of March 31, 2018 $ 125,047 $ 573,950 $ 33,298 $ 732,295 $ 27,731 Net income attributable to noncontrolling interests 1,036 23,424 — 24,460 6,583 Net subscriptions (redemptions) (36,328 ) — — (36,328 ) — Settlement of affiliate noncontrolling interest put: Payment — (15,547 ) — (15,547 ) — Change in redemption value — (12,345 ) — (12,345 ) — Distributions — (25,538 ) — (25,538 ) (6,820 ) Foreign exchange — (5,009 ) — (5,009 ) — Vesting/change in estimated redemption value — 1,037 13,925 14,962 — Balance as of December 31, 2018 $ 89,755 $ 539,972 $ 47,223 $ 676,950 $ 27,494 (1) Related to variable interest entities ("VIEs") and seeded investment products. (2) Related to Royce management equity plan. The following tables present the changes in redeemable noncontrolling interests by affiliate (exclusive of management equity plans): Redeemable noncontrolling interests EnTrust Global Clarion Partners RARE Infrastructure Other Total Balance as of March 31, 2019 $ 380,684 $ 123,502 $ 35,181 $ 1,228 $ 540,595 Net income (loss) attributable to noncontrolling interests 12,694 14,904 106 (115 ) 27,589 Business acquisition — — — 11,715 11,715 Purchase of affiliate noncontrolling interest: Payment (fair value portion) — — (8,789 ) — (8,789 ) Change in redemption value — — (25,708 ) — (25,708 ) Distributions (9,892 ) (12,880 ) — (3 ) (22,775 ) Foreign exchange — — (790 ) (43 ) (833 ) Change in estimated redemption value — 3,095 — — 3,095 Balance as of December 31, 2019 $ 383,486 $ 128,621 $ — $ 12,782 $ 524,889 Redeemable noncontrolling interests EnTrust Global Clarion Partners RARE Infrastructure Other Total Balance as of March 31, 2018 $ 386,884 $ 117,272 $ 68,285 $ 1,509 $ 573,950 Net income (loss) attributable to noncontrolling interests 9,752 12,460 1,417 (205 ) 23,424 Distributions (13,475 ) (10,359 ) (1,693 ) (11 ) (25,538 ) Settlement of affiliate noncontrolling interest put: Payment — — (15,547 ) (15,547 ) Change in redemption value — — (12,345 ) (12,345 ) Foreign exchange — — (5,009 ) — (5,009 ) Change in estimated redemption value — 1,037 — — 1,037 Balance as of December 31, 2018 $ 383,161 $ 120,410 $ 35,108 $ 1,293 $ 539,972 Redeemable noncontrolling interests of 35% of the outstanding equity of EnTrust Global and 18% of the outstanding equity of Clarion Partners can be put by the holders or called by Legg Mason for settlement at fair value subject to various conditions, including the passage of time. The amounts for noncontrolling interests, if reported at fair value in the Consolidated Balance Sheets, reflect the total business enterprise value of the combined entity, after appropriate discounts for lack of marketability and control. On May 10, 2019, Legg Mason purchased the 15% equity interest in RARE Infrastructure held by the firm's management team for total consideration of $21,988 . The initial cash payment of $11,967 , which included related dividends in arrears of $1,759 , was paid on May 10, 2019. The remaining balance will be due 50% one year after closing and 50% two years after closing, subject to certain conditions. The $11,440 difference between the fair value of the noncontrolling interest on the settlement date and the total consideration due (excluding dividends in arrears) was recorded as Compensation and benefits in the three months ended June 30, 2019. The $25,708 difference between the fair value and the carrying value of the noncontrolling interest of $ 34,497 on the settlement date was recorded as an increase to additional paid in capital. This purchase was part of Legg Mason's strategic restructuring, as further discussed in Note 15 , to pursue operational efficiencies between RARE Infrastructure and ClearBridge intended to reduce costs and enhance growth opportunities for both of the businesses. On July 2, 2018, the corporate minority owner of RARE Infrastructure exercised the put option for its 10% ownership interest. The settlement value of $ 15,547 was based on the midpoint of the valuations determined by the independent valuation experts appointed by Legg Mason and the corporate minority owner and was paid on October 10, 2018, along with $ 981 of dividends in arrears. The $ 12,345 difference between the settlement value and the carrying value of the noncontrolling interest of $ 27,892

Derivatives and Hedging

Derivatives and Hedging	9 Months Ended
Derivatives and Hedging	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Hedging	Derivatives and Hedging Legg Mason uses currency forwards to economically hedge the risk of movements in exchange rates, primarily between the U.S. dollar, British pound, Australian dollar, Singapore dollar, Japanese yen, and euro. All derivative transactions for which Legg Mason has certain legally enforceable rights of setoff are governed by International Swaps and Derivative Association ("ISDA") Master Agreements. For these derivative transactions, Legg Mason has one ISDA Master Agreement with each of the significant counterparties, which covers transactions with that counterparty. Each of the respective ISDA agreements provides for legally enforceable settlement netting and close-out netting between Legg Mason and that counterparty. Other assets recorded in the Consolidated Balance Sheets as of December 31, 2019 and March 31, 2019, were $3,074 and $4,183 , respectively. Other liabilities recorded in the Consolidated Balance Sheets as of December 31, 2019 and March 31, 2019, were $1,362 and $7,579 , respectively. Legg Mason also uses market hedges on certain seed capital investments by entering into futures contracts to sell index funds and treasuries that benchmark the hedged seed capital investments and has entered into total return swap arrangements with respect to certain Legg Mason sponsored ETFs, as further discussed below. Legg Mason has not designated any derivatives as hedging instruments for accounting purposes during the periods ended December 31, 2019, March 31, 2019, or December 31, 2018. As of December 31, 2019, Legg Mason had open currency forward contracts with aggregate notional amounts totaling $323,654 , and open futures contracts relating to seed capital investments with aggregate notional amounts totaling $95,910 . As of December 31, 2019, the weighted-average remaining contract terms for currency forward contracts was seven months and for futures contracts relating to seed capital investments was three months . Legg Mason has entered into various total return swap arrangements with financial intermediaries with respect to certain Legg Mason sponsored ETFs, which resulted in investments by each of the financial intermediaries in the respective ETF. Under the terms of each of the total return swap arrangements, Legg Mason receives the related investment gains and losses on the underlying shares of the ETF and pays a floating rate on the value of the underlying shares. Each of the total return swap arrangements allows either party to terminate all or part of the arrangement and provides for automatic termination upon occurrence of certain events. Each financial intermediary counterparty may hedge its total return swap position through an investment in the ETF and the financial intermediaries purchased interests in the related Legg Mason ETF on the date of the transactions. The aggregate notional amount for the two total return swaps outstanding as of December 31, 2019 was $34,907 , with a weighted-average remaining contract term of five months . The floating rate paid on the value of the underlying securities for all total return swap arrangements outstanding as of December 31, 2019 was three-month LIBOR plus 1.6% . In connection with the total return swap arrangements, Legg Mason executed futures contracts with notional amounts totaling $7,916 as of December 31, 2019 to partially hedge the gains and losses recognized on the total return swaps. These contracts had a weighted-average remaining contract term of three months . The amounts above are representative of the level of non-hedge designation derivative activity throughout the three and nine months ended December 31, 2019 and 2018. As further discussed in Note 16 , the total return swap arrangements create variable interests in the underlying funds for Legg Mason, and, if significant, Legg Mason is deemed to be the primary beneficiary. Accordingly, Legg Mason may consolidate ETF products with significant open total return swap arrangements. The following table presents the derivative assets and related offsets, if any: Gross Amounts Not Offset in the Balance Sheet Gross Amounts of Recognized Assets Gross Amounts Offset in the Balance Sheet Net Amount of Derivative Assets Presented in the Balance Sheet Financial Instruments Cash Collateral Net Amount as of Derivative instruments not designated as hedging instruments Currency forward contracts $ 4,092 $ (1,310 ) $ 2,782 $ — $ — $ 2,782 Total return swaps — — — 292 961 1,253 Total derivative instruments not designated as hedging instruments $ 4,092 $ (1,310 ) $ 2,782 $ 292 $ 961 $ 4,035 The following table presents the derivative liabilities and related offsets, if any: Gross Amounts Not Offset in the Balance Sheet Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Balance Sheet Net Amount of Derivative Liabilities Presented in the Balance Sheet Financial Instruments Cash Collateral Net Amount as of Derivative instruments not designated as hedging instruments Currency forward contracts $ (1,426 ) $ 986 $ (440 ) $ — $ — $ (440 ) Futures contracts relating to: Seed capital investments — — — (801 ) 4,809 4,008 Total return swaps — — — (49 ) 366 317 Total future contracts — — — (850 ) 5,175 4,325 Total return swaps (72 ) 890 818 Total derivative instruments not designated as hedging instruments $ (1,426 ) $ 986 $ (440 ) $ (922 ) $ 6,065 $ 4,703 The following table presents the derivative assets and related offsets, if any: Gross Amounts Not Offset in the Balance Sheet Gross Amounts of Recognized Assets Gross Amounts Offset in the Balance Sheet Net Amount of Derivative Assets Presented in the Balance Sheet Financial Instruments Cash Collateral Net amount as of Derivative instruments not designated as hedging instruments Currency forward contracts $ 3,997 $ (1,874 ) $ 2,123 $ — $ — $ 2,123 Total return swaps — — — 2,060 2,310 4,370 Total derivative instruments not designated as hedging instruments $ 3,997 $ (1,874 ) $ 2,123 $ 2,060 $ 2,310 $ 6,493 The following table presents the derivative liabilities and related offsets, if any: Gross Amounts Not Offset in the Balance Sheet Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Balance Sheet Net Amount of Derivative Liabilities Presented in the Balance Sheet Financial Instruments Cash Collateral Net amount as of March 31, 2019 Derivative instruments not designated as hedging instruments Currency forward contracts $ (7,465 ) $ 2,094 $ (5,371 ) $ — $ — $ (5,371 ) Futures contracts relating to: Seed capital investments — — — (1,798 ) 7,640 5,842 Total return swaps — — — (410 ) 1,104 694 Total futures contracts — — — (2,208 ) 8,744 6,536 Total derivative instruments not designated as hedging instruments $ (7,465 ) $ 2,094 $ (5,371 ) $ (2,208 ) $ 8,744 $ 1,165 The following table presents gains (losses) recognized in the Consolidated Statements of Income (Loss) on derivative instruments. As described above, the currency forward contracts and futures and forward contracts for seed capital investments included below are economic hedges of interest rate and market risk of certain operating and investing activities of Legg Mason. Three Months Ended December 31, 2019 2018 Income Statement Classification Gains Losses Gains Losses Derivatives not designated as hedging instruments Currency forward contracts relating to: Operating activities Other expense $ 10,325 $ (4,293 ) $ 3,110 $ (5,587 ) Seed capital investments Other non-operating income (expense) 651 (2,219 ) 1,503 (1,116 ) Futures contracts relating to: Seed capital investments Other non-operating income (expense) — (7,351 ) 16,520 (1 ) Total return swaps Other non-operating income (expense) 31 (563 ) 3,121 (467 ) Total return swaps Other non-operating income (expense) 384 (73 ) 203 (832 ) Total gain (loss) from derivatives not designated as hedging instruments $ 11,391 $ (14,499 ) $ 24,457 $ (8,003 ) Nine Months Ended December 31, 2019 2018 Income Statement Classification Gains Losses Gains Losses Derivatives not designated as hedging instruments Currency forward contracts relating to: Operating activities Other expense $ 7,813 $ (8,257 ) $ 9,369 $ (19,366 ) Seed capital investments Other non-operating income (expense) 2,356 (1,233 ) 5,523 (788 ) Futures contracts relating to: Seed capital investments Other non-operating income (expense) 398 (11,223 ) 19,224 (7,066 ) Total return swaps Other non-operating income (expense) 84 (1,441 ) 3,425 (3,418 ) Total return swaps Other non-operating income (expense) 1,885 — 1,869 (938 ) Total gain (loss) from derivatives not designated as hedging instruments $ 12,536 $ (22,154 ) $ 39,410 $ (31,576 )

Strategic Business Initiative (

Strategic Business Initiative (Notes)	9 Months Ended
Strategic Business Initiative (Notes)	Dec. 31, 2019
Restructuring [Abstract]
Restructuring and Related Activities Disclosure [Text Block]	15 . Strategic Restructuring In fiscal 2019, Legg Mason initiated a strategic restructuring to reduce costs, which includes corporate and distribution functions, as well as efficiency initiatives at certain smaller affiliates that operate outside of revenue-sharing arrangements. The strategic restructuring is expected to be substantially complete by the end of fiscal 2021. This plan involves restructuring costs beginning January 1, 2019, which are primarily comprised of employee termination benefits and retention incentives expensed over identified transition periods. The restructuring costs also include charges for consolidating leased office space and other costs, including professional fees. Legg Mason expects to incur total strategic restructuring costs in the range of $125,000 to $135,000 through March 2021 that are expected to result in future cost savings. Cumulative strategic restructuring costs incurred through December 31, 2019 were $76,649 , including $18,474 and $67,297 incurred during the three and nine months ended December 31, 2019. The table below presents a summary of changes in the strategic restructuring liability from January 1, 2019 through December 31, 2019, and cumulative charges incurred to date: Compensation and benefits Occupancy Other Total Balance as of January 1, 2019 $ — $ — $ — $ — Accrued charges — 2,090 6,504 8,594 Balance as of March 31, 2019 — 2,090 6,504 8,594 Accrued charges 40,860 4,427 8,059 53,346 Payments (7,992 ) (289 ) (9,886 ) (18,167 ) Balance as of December 31, 2019 $ 32,868 $ 6,228 $ 4,677 $ 43,773 Non-cash charges (1) Three months ended March 31, 2019 $ — $ 758 $ — $ 758 Nine months ended December 31, 2019 12,448 1,503 — 13,951 Total $ 12,448 $ 2,261 $ — $ 14,709 Cumulative charges incurred through December 31, 2019 $ 53,308 $ 8,778 $ 14,563 $ 76,649 (1) Includes stock-based compensation expense and accelerated fixed asset depreciation. The estimates for the remaining strategic restructuring costs expected to be incurred through fiscal 2021 are as follows: Minimum Maximum Compensation and benefits $ 12,000 $ 17,000 Occupancy 16,000 18,000 Other costs 20,000 23,000 Total $ 48,000 $ 58,000 While management expects the total estimated costs to be within the range disclosed, the ultimate nature and timing of the costs may differ from those presented above.

Variable Interest Entities and

Variable Interest Entities and Consolidation of Investment Vehicles	9 Months Ended
	Dec. 31, 2019
Variable Interest Entities and Consolidation of Investment Vehicles [Abstract]
Consolidated Investment Vehicles and Other Variable Interest Entities Disclosure [Text Block]	Variable Interest Entities and Consolidated Investment Vehicles In accordance with financial accounting standards, Legg Mason consolidates certain sponsored investment products, some of which are designated as CIVs. As presented in the table below, Legg Mason concluded it was the primary beneficiary of certain VIEs because it held significant financial interests in the funds. In addition, Legg Mason has entered into various total return swap arrangements with financial intermediaries with respect to certain Legg Mason sponsored ETFs. Under the terms of the total return swaps, Legg Mason absorbs all of the related gains and losses on the underlying ETF investments of these financial intermediaries, and therefore has variable interests in ETFs with open total return swap arrangements and, if significant, Legg Mason is deemed to be the primary beneficiary of such ETFs. Because it was determined to be the primary beneficiary of these VIEs, Legg Mason consolidated and designated the following funds as CIVs in the Consolidated Balance Sheets as of: December 31, 2019 March 31, 2019 December 31, 2018 Number of Consolidated Funds Legg Mason Investment in Funds (1) Number of Consolidated Funds Legg Mason Investment in Funds (1) Number of Consolidated Funds Legg Mason Investment in Funds (1) Sponsored investment partnerships 2 $ 9,419 2 $ 11,671 2 $ 12,863 Trust structure foreign mutual funds 6 21,669 7 23,005 8 49,251 Employee trust structure funds 1 4,564 2 6,215 2 6,963 ETFs (2) 2 2,764 3 2,821 2 2,487 Total 11 $ 38,416 14 $ 43,712 14 $ 71,564 (1) Represents Legg Mason's maximum risk of loss, excluding uncollected advisory fees. (2) Under the total return swap arrangements, Legg Mason receives the related investment gains and losses on investments in two of Legg Mason's ETFs with notional amounts totaling $34,907 as of December 31, 2019. See Note 14 for additional information regarding total return swaps. The assets of these CIVs are primarily comprised of investment securities and as of March 31, 2019, the liabilities of these CIVs were primarily comprised of payables for purchased securities. Investors and creditors of these CIVs have no recourse to the general credit or assets of Legg Mason beyond its investment in these funds. Legg Mason also consolidates certain voting rights entities ("VRE") products with seed capital investments where Legg Mason maintains a controlling financial interest in the product. As of December 31, 2019, March 31, 2019 and December 31, 2018, Legg Mason consolidated four, five, and seven VRE products with seed capital investments totaling $39,130 , $24,924 , and $29,355 , respectively. The following tables reflect the impact of CIVs and other consolidated sponsored investment products in the Consolidated Balance Sheets and the Consolidated Statements of Income (Loss): Consolidating Balance Sheets December 31, 2019 March 31, 2019 Balance Before Consolidation of CIVs and Other (1) CIVs and Other (1) Reclassifications & Eliminations Consolidated Totals Balance Before Consolidation of CIVs and Other (1) CIVs and Other (1) Reclassifications & Eliminations Consolidated Totals Current Assets $ 1,896,010 $ 117,167 $ (37,245 ) $ 1,975,932 $ 1,916,485 $ 144,091 $ (40,720 ) $ 2,019,856 Non-current assets 6,061,015 3,942 (1,171 ) 6,063,786 5,768,265 8,993 (2,992 ) 5,774,266 Total Assets $ 7,957,025 $ 121,109 $ (38,416 ) $ 8,039,718 $ 7,684,750 $ 153,084 $ (43,712 ) $ 7,794,122 Current Liabilities $ 929,495 $ 1,364 $ — $ 930,859 $ 1,104,002 $ 5,742 $ — $ 1,109,744 Non-current liabilities 2,605,229 — — 2,605,229 2,302,463 — — 2,302,463 Total Liabilities 3,534,724 1,364 — 3,536,088 3,406,465 5,742 — 3,412,207 Redeemable Non-controlling interests 587,024 — 81,329 668,353 588,746 — 103,630 692,376 Total Stockholders’ Equity 3,835,277 119,745 (119,745 ) 3,835,277 3,689,539 147,342 (147,342 ) 3,689,539 Total Liabilities and Equity $ 7,957,025 $ 121,109 $ (38,416 ) $ 8,039,718 $ 7,684,750 $ 153,084 $ (43,712 ) $ 7,794,122 (1) Other represents consolidated sponsored investment product VREs that are not designated as CIVs. Consolidating Statements of Income (Loss) $ 51,439 Three Months Ended December 31, 2019 December 31, 2018 Balance Before (1) CIVs and Other (1) Eliminations Consolidated Totals Balance Before (1) CIVs and Other (1) Eliminations Consolidated Totals Total Operating Revenues $ 753,983 $ — $ (69 ) $ 753,914 $ 704,477 $ — $ (155 ) $ 704,322 Total Operating Expenses 623,817 166 (63 ) 623,920 940,561 308 (120 ) 940,749 Operating Income (Loss) 130,166 (166 ) (6 ) 129,994 (236,084 ) (308 ) (35 ) (236,427 ) Total Non-Operating Income (Expense) (7,300 ) 569 1,404 (5,327 ) (32,158 ) 2,612 (771 ) (30,317 ) Income (Loss) Before Income Tax Provision (Benefit) 122,866 403 1,398 124,667 (268,242 ) 2,304 (806 ) (266,744 ) Income tax provision (benefit) 33,664 — — 33,664 (60,354 ) — — (60,354 ) Net Income (Loss) 89,202 403 1,398 91,003 (207,888 ) 2,304 (806 ) (206,390 ) Less: Net income (loss) attributable to noncontrolling interests 14,427 (245 ) 2,046 16,228 9,000 242 1,256 10,498 Net Income (Loss) Attributable to Legg Mason, Inc. $ 74,775 $ 648 $ (648 ) $ 74,775 $ (216,888 ) $ 2,062 $ (2,062 ) $ (216,888 ) (1) Other represents consolidated sponsored investment products (VREs) that are not designated as CIVs. Nine Months Ended December 31, 2019 December 31, 2018 Balance Before Consolidation of CIVs and Other (1) CIVs and Other (1) Eliminations Consolidated Totals Balance Before (1) CIVs and Other (1) Eliminations Consolidated Totals Total Operating Revenues $ 2,202,888 $ — $ (350 ) $ 2,202,538 $ 2,211,115 $ — $ (461 ) $ 2,210,654 Total Operating Expenses 1,862,253 1,292 87 1,863,632 2,184,807 1,386 (516 ) 2,185,677 Operating Income (Loss) 340,635 (1,292 ) (437 ) 338,906 26,308 (1,386 ) 55 24,977 Total Non-Operating Income (Expense) (40,072 ) 15,625 (4,890 ) (29,337 ) (74,131 ) 2,070 297 (71,764 ) Income (Loss) Before Income Tax Provision 300,563 14,333 (5,327 ) 309,569 (47,823 ) 684 352 (46,787 ) Income tax provision 80,466 — — 80,466 165 — — 165 Net Income (Loss) 220,097 14,333 (5,327 ) 229,103 (47,988 ) 684 352 (46,952 ) Less: Net income (loss) attributable to noncontrolling interests 32,889 721 8,285 41,895 30,007 115 921 31,043 Net Income (Loss) Attributable to Legg Mason, Inc. $ 187,208 $ 13,612 $ (13,612 ) $ 187,208 $ (77,995 ) $ 569 $ (569 ) $ (77,995 ) Non-Operating Income (Expense) of CIVs and Other includes interest income, interest expense, and net gains (losses) on investments. The consolidation of CIVs has no impact on Net Income (Loss) Attributable to Legg Mason, Inc. As of December 31, 2019 and March 31, 2019, financial assets of CIVs carried at fair value totaling $78,957 and $70,197 , respectively, were valued using Level 1 inputs, $25,536 and $55,182 , respectively, were valued using Level 2 inputs, and $3,619 and $12,547 , respectively, were valued using NAV as a practical expedient. As of March 31, 2019, financial liabilities of CIVs carried at fair value of $4,217 were valued using Level 2 inputs. There were no transfers between Level 1 and Level 2 assets or liabilities during the three and nine months ended December 31, 2019 and 2018 . The NAVs used as a practical expedient by CIVs have been provided by the investees and have been derived from the fair values of the underlying investments as of the respective reporting dates. The following table summarizes the nature of these investments and any related liquidation restrictions or other factors, which may impact the ultimate value realized: Fair Value Determined Using NAV As of December 31, 2019 Category of Investment Investment Strategy December 31, 2019 March 31, 2019 Unfunded Commitments Remaining Term Hedge funds Global macro, fixed income, long/short equity, systematic, emerging market, U.S. and European hedge $ 3,619 (1) $ 12,547 n/a n/a n/a - not applicable (1) Redemption restrictions: 22% monthly redemption; 77% quarterly redemption; and 1% are subject to three to five-year lock-up or side pocket provisions. Legg Mason's carrying value and maximum risk of loss for VIEs in which Legg Mason holds a variable interest, but for which it was not the primary beneficiary, were as follows: As of December 31, 2019 As of March 31, 2019 Equity Interests on the Consolidated Balance Sheet (1) Maximum Risk of Loss (2) Equity Interests on the Consolidated Balance Sheet (1) Maximum Risk of Loss (2) Real Estate Investment Trusts $ 12,312 $ 14,052 $ 10,812 $ 15,241 Other investment funds 31,090 49,646 25,155 45,897 Total $ 43,402 $ 63,698 $ 35,967 $ 61,138 (1) Amounts are related to investments in proprietary and other fund products. (2) Includes equity investments the Company has made or is required to make and any earned but uncollected management fees. The Company's total AUM of unconsolidated VIEs was $29,677,965 and $29,025,764 as of December 31, 2019 and March 31, 2019, respectively. The assets of these VIEs are primarily comprised of cash and cash equivalents and investment securities, and the liabilities are primarily comprised of various expense accruals. These VIEs were not consolidated because Legg Mason does not have both the power to direct significant economic activities of the entity and rights/obligations associated with benefits/losses that could be significant to the entity.

Significant Accounting Polici_2

Significant Accounting Policies Significant Accounting Policies (Policies)	9 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Lessee, Leases [Policy Text Block]	Leases Effective April 1, 2019 Legg Mason adopted updated accounting guidance on leases which requires right-of-use ("ROU") assets and lease liabilities to be recorded on the balance sheet for leases. The guidance specifies that at the inception of a contract, an entity must determine whether the contract is or contains a lease. The contract is or contains a lease if the contract conveys the right to control the use of the property, plant, or equipment for a designated term in exchange for consideration. Legg Mason’s evaluation of its contracts to determine whether they are or contain a lease involves assessing whether there is a right to obtain substantially all of the economic benefits from the use and the right to direct the use of the identified asset in the contract. Legg Mason adopted the guidance on a modified retrospective basis as of April 1, 2019, such that related amounts in prior periods have not been restated. Legg Mason has operating leases that primarily relate to real property and financing leases that relate to equipment. As a practical expedient, Legg Mason has elected to not capitalize leases with a term of 12 months or less without a purchase option that it is likely to exercise. Also as a practical expedient for disclosure, Legg Mason has elected to not separate lease and non-lease components on operating and financing leases. Lease components are payment items directly attributable to the use of the underlying asset, while non-lease components are explicit elements of a contract not directly related to the use of the underlying asset, including pass through operating expenses such as common area maintenance, real estate taxes and utilities. ROU assets and lease liabilities are recognized on the consolidated balance sheet at the present value of the future lease payments over the life of the lease term. As implicit rates for leases are not determinable, the Company uses discount rates based on incremental borrowing rates, on a collateralized basis, for the respective underlying assets, for terms similar to the respective leases. Lease costs are included as Occupancy expense in the Consolidated Statements of Income (Loss). Fixed base payments on operating leases paid directly to the lessor are recorded as lease expense on a straight-line basis. Related variable payments based on usage, changes in an index or market rate are expensed as incurred. Payments on financing leases are recorded as lease expense on a level-yield basis. Upon adoption on April 1, 2019, Legg Mason recorded ROU assets of $342,418 and lease liabilities of $411,115 related to its real property operating leases and equipment financing leases. As further discussed in Note 8 , Legg Mason has subleased or has vacated and is pursuing subleases for certain office space. As of March 31, 2019, the lease reserve liability for subleased space and vacated space for which subleases were being pursued of $24,063 was included in other current and non-current liabilities on the Consolidated Balance Sheet under prior accounting guidance. Upon adoption of the updated guidance, the existing lease reserve liability was reclassified as a reduction of the ROU assets. ROU assets are tested for impairment when circumstances indicate that the carrying values may not be recoverable. The adoption of this guidance did not require a cumulative effect adjustment or have a material impact on the Consolidated Statements of Income (Loss) or Consolidated Statements of Cash Flows. See Note 8 for additional information.
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Developments In January 2017, the Financial Accounting Standards Board ("FASB") updated guidance to simplify the test for goodwill impairment. The updated guidance still requires entities to perform annual goodwill impairment tests by comparing the fair value of a reporting unit with its related carrying amount, but it eliminates the requirement to potentially calculate the implied fair value of goodwill to determine the amount of impairment, if any. Under the new guidance, an entity should recognize an impairment charge if the reporting unit's carrying amount exceeds the reporting unit’s fair value, in the amount of such excess. The guidance will be effective in fiscal 2021, unless adopted earlier. Legg Mason is evaluating its adoption. In August 2018, the FASB updated the guidance to clarify accounting for implementation costs incurred for a cloud computing arrangement that is a service contract. The update conforms the requirements for capitalizing implementation costs incurred in a cloud computing arrangement that is a service contract with the accounting guidance that provides for capitalization of costs incurred to develop or obtain internal-use-software. The updated guidance is effective for Legg Mason in fiscal 2021, unless adopted earlier. Legg Mason is evaluating its adoption. In August 2018, the FASB also updated the guidance for fair value measurements. The updated guidance modifies disclosure requirements based on the revised FASB Conceptual Framework for Financial Reporting finalized in August 2018 to improve effectiveness of financial statement disclosures. The updated guidance will be effective in fiscal 2021, unless adopted earlier. Legg Mason is evaluating its adoption.

Fair Values of Assets and Lia_2

Fair Values of Assets and Liabilities (Tables) - Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]	9 Months Ended
	Dec. 31, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Assets Measured on Recurring Basis [Table Text Block]	The fair values of financial assets and (liabilities) of the Company were determined using the following categories of inputs: As of December 31, 2019 Quoted prices in active markets Significant other observable inputs Significant unobservable inputs Investments measured at NAV Total Assets: Cash equivalents (1) $ 429,557 $ 13,098 $ — $ — $ 442,655 Equity investments: (2) Seed capital investments 73,738 29,352 21,546 1,650 126,286 Investments related to long-term incentive plans 258,040 — — — 258,040 Other investments 14,965 2,027 — — 16,992 Equity method investments: (3) Seed capital investments (4) — — 43,340 12,035 55,375 Investments related to long-term incentive plans (2) — — — 7,625 7,625 Other investments (4) — — 53 9,533 9,586 Adjusted cost investments (4) — 73 26,366 — 26,439 Derivative assets (5) 3,074 — — — 3,074 Total $ 779,374 $ 44,550 $ 91,305 $ 30,843 $ 946,072 Liabilities: Contingent consideration liabilities (6) $ — $ — $ (3,376 ) $ — $ (3,376 ) Derivative liabilities (5) (1,362 ) — — — (1,362 ) Total $ (1,362 ) $ — $ (3,376 ) $ — $ (4,738 ) As of March 31, 2019 Quoted prices in active markets Significant other observable inputs Significant unobservable inputs Investments measured at NAV Total Assets: Cash equivalents (1) $ 556,231 $ 20,160 $ — $ — $ 576,391 Equity investments: (2) Seed capital investments 98,276 30,601 1,455 2,183 132,515 Investments related to long-term incentive plans 211,802 — — — 211,802 Other investments 19,486 2,142 — — 21,628 Equity method investments: (3) Seed capital investments (4) — — 40,854 10,675 51,529 Investments related to long-term incentive plans (2) — — — 11,184 11,184 Other investments (4) — — 1,218 10,251 11,469 Adjusted cost investments (4) — 74 12,171 — 12,245 Derivative assets (5) 4,183 — — — 4,183 Total $ 889,978 $ 52,977 $ 55,698 $ 34,293 $ 1,032,946 Liabilities: Contingent consideration liabilities (6) $ — $ — $ (1,415 ) $ — $ (1,415 ) Derivative liabilities (5) (7,579 ) — — — (7,579 ) Total $ (7,579 ) $ — $ (1,415 ) $ — $ (8,994 ) (1) Cash investments in actively traded money market funds are classified as Level 1. Cash investments in time deposits and other are measured at amortized cost, which approximates fair value because of the short time between purchase of the instrument and its expected realization and are classified as Level 2. (2) Included in Investment securities on the Consolidated Balance Sheets. (3) Primarily investments in private equity and real estate funds. These equity method investments are investment companies that primarily record underlying investments at fair value. Therefore, the fair value of these investments is measured using Legg Mason's share of the investee's underlying net income or loss, which is predominately representative of fair value adjustments in the investments held by the equity method investee. Other equity method investments not measured at fair value on a recurring basis of $27,051 and $28,160 as of December 31, 2019 and March 31, 2019, respectively, are excluded from the tables above. (4) Included in Other noncurrent assets in the Consolidated Balance Sheets. (5) See Note 14 . (6) See Note 9 .
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	The changes in financial assets and (liabilities) measured at fair value using significant unobservable inputs (Level 3) are presented in the tables below: Balance as of September 30, 2019 Purchases Sales Redemptions/ Settlements/ Other Transfers Realized and unrealized gains/(losses), net Balance as of December 31, 2019 Assets: Equity investments - seed capital $ 20,200 $ 1,000 — — — 346 21,546 Equity method investments: Seed capital investments 43,252 283 — (2,073 ) — 1,878 43,340 Other 1,297 — — (1,209 ) — (35 ) 53 Adjusted cost investments 22,869 3,497 — — — — 26,366 $ 87,618 $ 3,780 $ — $ (3,282 ) $ — $ 1,843 $ 91,305 Liabilities: Contingent consideration liabilities $ (3,625 ) $ — n/a $ 250 n/a $ (1 ) $ (3,376 ) Balance as of September 30, 2018 Purchases Sales Redemptions/ Settlements/ Other Transfers Realized and unrealized gains/(losses), net Balance as of December 31, 2018 Assets: Equity investments - seed capital $ 1,394 $ — $ — $ — $ — $ (128 ) $ 1,266 Equity method investments: Seed capital investments 37,020 5,516 — (1,880 ) — 398 41,054 Other 1,840 — — (19 ) — — 1,821 Adjusted cost investments 10,906 1,063 — — — 3 11,972 $ 51,160 $ 6,579 $ — $ (1,899 ) $ — $ 273 $ 56,113 Liabilities: Contingent consideration liabilities $ (1,900 ) $ — n/a $ — n/a $ — $ (1,900 ) Balance Purchases Sales Redemptions/ Settlements/ Other Transfers Realized and unrealized gains/(losses), net Balance Assets: Equity Investments - seed capital $ 1,455 $ 21,200 $ — $ (1,457 ) $ — $ 348 $ 21,546 Equity method investments: Seed capital investments 40,854 2,621 — (3,045 ) — 2,910 43,340 Other 1,218 — — (1,222 ) — 57 53 Adjusted cost investments 12,171 14,318 — (125 ) — 2 26,366 $ 55,698 $ 38,139 $ — $ (5,849 ) $ — $ 3,317 $ 91,305 Liabilities: Contingent consideration liabilities $ (1,415 ) (3,389 ) n/a $ 250 n/a $ 1,178 $ (3,376 ) Balance Purchases Sales Redemptions/ Settlements/ Other Transfers Realized and unrealized gains/(losses), net Balance Assets: Equity Investments - seed capital $ 1,242 $ — $ — $ — $ — $ 24 $ 1,266 Equity method investments: Seed capital investments 33,725 9,483 — (4,280 ) — 2,126 41,054 Other — 1,650 — (19 ) — 190 1,821 Adjusted cost investments 6,951 5,063 — (2 ) — (40 ) 11,972 $ 41,918 $ 16,196 $ — $ (4,301 ) $ — $ 2,300 $ 56,113 Liabilities: Contingent consideration liabilities $ (5,607 ) $ — n/a $ 4,319 n/a $ (612 ) $ (1,900 )
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table Text Block]	The following table summarizes the nature of these investments and any related liquidation restrictions or other factors which may impact the ultimate value realized: Fair Value Determined Using NAV As of December 31, 2019 Category of Investment Investment Strategy December 31, 2019 March 31, 2019 Unfunded Commitments Remaining Term Funds-of-hedge funds Global macro, fixed income, long/short equity, natural resources, systematic, emerging market, European hedge $ 11,905 (1) $ 9,910 n/a n/a Hedge funds Fixed income - developed market, event driven, fixed income - hedge, relative value arbitrage, European hedge 1,049 1,515 n/a n/a Private equity funds Long/short equity 10,244 (2) 11,636 $ 5,698 Up to 10 years Equity method investments related to long-term incentive plans Alternatives, structured securities, short-dated fixed income 7,625 (2) 11,185 n/a n/a Other Various 20 47 n/a Various Total $ 30,843 $ 34,293 $ 5,698 n/a - not applicable (1) Liquidation restrictions: 14% monthly redemption, 1% quarterly redemption, and 85% are not subject to redemption or are not currently redeemable. (2) Liquidations are expected over the remaining term.

Fixed Assets (Tables)

Fixed Assets (Tables)	9 Months Ended
Fixed Assets (Tables)	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Components of fixed assets	The following table reflects the components of fixed assets as of: December 31, 2019 March 31, 2019 Software $ 276,096 $ 269,944 Leasehold improvements 213,439 212,742 Equipment 162,795 159,421 Total cost 652,330 642,107 Less: accumulated depreciation and amortization (513,495 ) (492,118 ) Fixed assets, net $ 138,835 $ 149,989

Intangible Assets and Goodwill

Intangible Assets and Goodwill (Tables)	9 Months Ended
Intangible Assets and Goodwill (Tables)	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-lived and Indefinite-lived Intangible Assets by Major Class [Table Text Block]	The following table reflects the components of intangible assets as of: December 31, 2019 March 31, 2019 Amortizable intangible asset management contracts and other Cost $ 372,808 $ 366,930 Accumulated amortization (257,410 ) (240,488 ) Net (1) 115,398 126,442 Indefinite–life intangible assets U.S. domestic mutual fund management contracts 2,106,351 2,106,351 Clarion Partners fund management contracts 505,200 505,200 EnTrust Global fund management contracts 126,804 126,804 Other fund management contracts 475,069 473,360 Trade names 48,695 48,602 3,262,119 3,260,317 Intangible assets, net $ 3,377,517 $ 3,386,759 (1) As of December 31, 2019, includes $5,305 related to the acquisition of Gramercy by Clarion Partners. See Note 4 for additional information.
Changes in carrying value of goodwill	The change in carrying value of goodwill is summarized below: Gross Book Value Accumulated Impairment Net Book Value Balance as of March 31, 2019 $ 3,045,454 $ (1,161,900 ) $ 1,883,554 Impact of excess tax basis amortization (8,256 ) — (8,256 ) Changes in foreign exchange rates 603 — 603 Business acquisition (1) 20,196 — 20,196 Balance as of December 31, 2019 $ 3,057,997 $ (1,161,900 ) $ 1,896,097
Estimated amortization expense	Estimated amortization expense for each of the next five fiscal years and thereafter is as follows: Remaining fiscal 2020 $ 5,640 2021 21,834 2022 21,485 2023 20,725 2024 19,896 Thereafter 25,818 Total $ 115,398

Long-Term Debt (Tables)

Long-Term Debt (Tables)	9 Months Ended
Long-Term Debt (Tables)	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments [Table Text Block]	Long-term debt, net, consists of the following: December 31, 2019 March 31, 2019 Carrying Value Unamortized Discount (Premium) Unamortized Debt Issuance Costs Maturity Amount Carrying Value 3.95% Senior Notes due July 2024 $ 248,917 $ 206 $ 877 $ 250,000 $ 248,738 4.75% Senior Notes due March 2026 447,786 — 2,214 450,000 447,521 5.625% Senior Notes due January 2044 548,079 (2,938 ) 4,859 550,000 548,020 6.375% Junior Notes due March 2056 242,614 — 7,386 250,000 242,461 5.45% Junior Notes due September 2056 485,017 — 14,983 500,000 484,711 2.7% Senior Notes due July 2019 — — — — 250,301 Subtotal 1,972,413 (2,732 ) 30,319 2,000,000 2,221,752 Less: Current portion — — — — (250,301 ) Total $ 1,972,413 $ (2,732 ) $ 30,319 $ 2,000,000 $ 1,971,451

Leases (Tables)

Leases (Tables)	9 Months Ended
Leases (Tables)	Dec. 31, 2019
Lease Disclosures [Abstract]
Schedule of Balance Sheet Information Related to Operating and Finance Leases [Table Text Block]	Leases included in the Consolidated Balance Sheets were as follows: Classification As of December 31, 2019 Operating leases: Operating lease ROU assets Right-of-use assets $ 294,174 Operating lease liabilities Lease liabilities 361,921 Finance leases: Property and equipment, gross Right-of-use assets $ 2,134 Less: accumulated depreciation Right-of-use assets (643 ) Property and equipment, net $ 1,491 Finance lease liabilities Lease liabilities $ 1,367
Lease, Cost [Table Text Block]	The components of lease expense included in the Consolidated Statement of Income (Loss) were as follows: Classification Three Months Ended December 31, 2019 Nine Months Ended December 31, 2019 Operating lease cost Occupancy expense $ 25,361 $ 67,172 Financing lease cost: Amortization of right-of-use asset Occupancy expense 251 737 Interest on lease liabilities Interest expense 11 36 Total finance lease cost 262 773 Short-term lease cost Occupancy expense 1,190 4,885 Variable lease cost (1) Occupancy expense 6,599 17,788 Less: sublease billings Occupancy expense (6,091 ) (18,624 ) Net lease cost (2) $ 27,321 $ 71,994 (1) Variable lease cost includes operating expenses, real estate and other taxes. Variable lease costs are determined by whether they are to be included in base rent and if amounts are based on a consumer price index. (2) Excludes other occupancy expense of $5,292 and $13,123
Lessee Operating and Finance Lease Liability Maturity Table. [Table Text Block]	As of December 31, 2019, undiscounted future cash flows for each of the next five fiscal years and thereafter related to operating and finance leases were as follows: Operating Leases Finance Leases Total Remaining fiscal 2020 $ 23,181 $ 263 $ 23,444 2021 88,048 714 88,762 2022 86,385 271 86,656 2023 84,530 131 84,661 2024 70,210 35 70,245 Thereafter 46,472 5 46,477 Total lease payments 398,826 1,419 400,245 Less: Imputed interest (36,905 ) (52 ) (36,957 ) Present value of lease liabilities $ 361,921 $ 1,367 $ 363,288
Schedule Of Supplemental Information Related To Operating and Finance Leases [Table Text Block]	As of December 31, 2019, the weighted-average remaining lease terms and weighted-average discount rates for operating and finance leases were as follows: Operating Leases Finance Leases Weighted-average remaining lease term (in years) 4.8 2.0 Weighted-average discount rates 4.0 % 3.1 %
Schedule of Supplemental Cash Flow Information Related To Operating and Finance Leases [Table Text Block]	Supplemental cash flow information related to leases was as follows: Nine Months Ended December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 64,470 Financing cash flows from finance leases 727
Lessee, Operating Lease, Disclosure [Table Text Block]	As of March 31, 2019, minimum aggregate rentals under operating leases were as follows: Operating Leases (1) 2020 $ 90,667 2021 86,095 2022 84,485 2023 83,425 2024 72,192 Thereafter 47,240 Total $ 464,104

Stock-Based Compensation Share-

Stock-Based Compensation Share-based Compensation (Tables)	9 Months Ended
Stock-Based Compensation Share-based Compensation (Tables)	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award
Schedule of Compensation Cost for Share-based Payment Arrangements	he components of Legg Mason's total stock-based compensation expense were as follows: Three Months Ended December 31, Nine Months Ended December 31, 2019 2018 2019 2018 Restricted stock and restricted stock units $ 12,025 $ 11,668 $ 43,507 $ 38,707 Stock options 728 1,057 2,643 3,513 Employee stock purchase plan 77 96 415 480 Non-employee director awards — — 1,000 1,025 Affiliate management equity plans 23 719 1,670 2,213 Performance share units 2,564 1,202 8,688 4,014 Employee stock trust 9 8 26 23 Total stock-based compensation expense $ 15,426 $ 14,750 $ 57,949 $ 49,975
Restricted stock and restricted stock unit transactions	Restricted stock and restricted stock unit transactions are summarized below: Nine Months Ended December 31, 2019 2018 Number of Shares Weighted-Average Grant Date Value Number of Shares Weighted-Average Grant Date Value Unvested shares at March 31 3,045 $ 37.76 3,299 $ 38.09 Granted 1,205 35.50 1,179 39.05 Vested (1,288 ) 38.70 (1,286 ) 39.73 Canceled/forfeited (59 ) 36.88 (108 ) 37.62 Unvested shares at December 31 2,903 $ 36.43 3,084 $ 37.80
Stock options transactions	Stock option transactions under Legg Mason's equity incentive plans are summarized below: Nine Months Ended December 31, 2019 2018 Number of Shares Weighted-Average Exercise Price Per Share Number of Shares Weighted-Average Exercise Price Per Share Options outstanding at March 31 4,115 $ 39.05 4,437 $ 38.78 Exercised (369 ) 31.55 (189 ) 31.62 Canceled/forfeited (80 ) 46.18 (95 ) 43.92 Options outstanding at December 31 3,666 $ 39.65 4,153 $ 38.99
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Assumptions used to determine the fair value of performance share awards	The following assumptions were used in the Monte Carlo pricing models for the May 2019 and 2018 grants: May 2019 May 2018 Expected dividend yield 4.41 % 3.49 % Risk-free interest rate 2.11 % 2.71 % Average expected volatility 23.96 % 26.14 %

Revenue Disaggregation of Reven

Revenue Disaggregation of Revenue (Tables)	9 Months Ended
Revenue Disaggregation of Revenue (Tables)	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue [Table Text Block]	The following table presents Total Operating Revenues disaggregated by geographic location: Three Months Ended December 31, Nine Months Ended December 31, 2019 2018 2019 2018 United States $ 583,080 $ 547,696 $ 1,730,546 $ 1,711,426 United Kingdom 56,264 35,142 121,303 111,739 Other International 114,570 121,484 350,689 387,489 Total Operating Revenues $ 753,914 $ 704,322 $ 2,202,538 $ 2,210,654
AssetClass [Member]
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue [Table Text Block]	The following table presents Total Operating Revenues disaggregated by asset class: Three Months Ended December 31, Nine Months Ended December 31 2019 2018 2019 2018 Equity $ 293,130 $ 296,738 $ 875,965 $ 931,350 Fixed Income 299,121 275,559 873,687 855,343 Alternative 139,061 110,390 384,068 361,239 Liquidity 22,602 21,635 68,818 62,722 Total Operating Revenues $ 753,914 $ 704,322 $ 2,202,538 $ 2,210,654

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
Earnings Per Share (Tables)	Dec. 31, 2019
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The following table presents the computations of basic and diluted earnings per share attributable to Legg Mason, Inc. shareholders ("EPS"): Three Months Ended December 31, Nine Months Ended December 31, 2019 2018 2019 2018 Basic weighted-average shares outstanding for EPS 86,878 85,537 86,666 85,381 Potential common shares: Dilutive employee stock options 287 — 266 — Diluted weighted-average shares outstanding for EPS 87,165 85,537 86,932 85,381 Net Income (Loss) Attributable to Legg Mason, Inc. $ 74,775 $ (216,888 ) $ 187,208 $ (77,995 ) Less: Earnings (distributed and undistributed) allocated to participating securities 2,428 1,049 6,138 3,190 Net Income (Loss) (Distributed and Undistributed) Allocated to Shareholders (Excluding Participating Securities) $ 72,347 $ (217,937 ) $ 181,070 $ (81,185 ) Net Income (Loss) per share Attributable to Legg Mason, Inc. Shareholders Basic $ 0.83 $ (2.55 ) $ 2.09 $ (0.95 ) Diluted 0.83 (2.55 ) 2.08 (0.95 )

Noncontrolling Interests Rollfo

Noncontrolling Interests Rollforward (Tables)	9 Months Ended
Noncontrolling Interests Rollforward (Tables)	Dec. 31, 2019
Noncontrolling Interest [Line Items]
Net Income (Loss) Attributable to Noncontrolling Interests [Table Text Block]	Three Months Ended December 31, Nine Months Ended December 31, 2019 2018 2019 2018 Net income attributable to redeemable noncontrolling interests $ 14,266 $ 8,852 $ 36,595 $ 24,460 Net income attributable to nonredeemable noncontrolling interests 1,962 1,646 5,300 6,583 Total $ 16,228 $ 10,498 $ 41,895 $ 31,043
Redeemable Noncontrolling Interest [Table Text Block]	redeemable and nonredeemable noncontrolling interests: Redeemable noncontrolling interests Consolidated investment vehicles (1) and other Affiliate Noncontrolling interests Management equity plans Total Nonredeemable noncontrolling interests (3) Balance as of March 31, 2019 $ 103,630 $ 540,595 $ 48,151 $ 692,376 $ 29,784 Net income attributable to noncontrolling interests 9,006 27,589 — 36,595 5,300 Business acquisition 11,715 — 11,715 — Net subscriptions (redemptions) (31,307 ) — — (31,307 ) — Purchase of affiliate noncontrolling interest: Payment (fair value portion) — (8,789 ) — (8,789 ) — Change in redemption value — (25,708 ) — (25,708 ) — Distributions — (22,775 ) — (22,775 ) (4,519 ) Foreign exchange — (833 ) — (833 ) — Vesting/change in estimated redemption value — 3,095 13,984 17,079 — Balance as of December 31, 2019 $ 81,329 $ 524,889 $ 62,135 $ 668,353 $ 30,565 Redeemable noncontrolling interests Consolidated investment vehicles (1) and other Affiliate Noncontrolling interests Management equity plans Total Nonredeemable noncontrolling interests (2) Balance as of March 31, 2018 $ 125,047 $ 573,950 $ 33,298 $ 732,295 $ 27,731 Net income attributable to noncontrolling interests 1,036 23,424 — 24,460 6,583 Net subscriptions (redemptions) (36,328 ) — — (36,328 ) — Settlement of affiliate noncontrolling interest put: Payment — (15,547 ) — (15,547 ) — Change in redemption value — (12,345 ) — (12,345 ) — Distributions — (25,538 ) — (25,538 ) (6,820 ) Foreign exchange — (5,009 ) — (5,009 ) — Vesting/change in estimated redemption value — 1,037 13,925 14,962 — Balance as of December 31, 2018 $ 89,755 $ 539,972 $ 47,223 $ 676,950 $ 27,494 (1) Related to variable interest entities ("VIEs") and seeded investment products. (2) Related to Royce management equity plan. The following tables present the changes in redeemable noncontrolling interests by affiliate (exclusive of management equity plans): Redeemable noncontrolling interests EnTrust Global Clarion Partners RARE Infrastructure Other Total Balance as of March 31, 2019 $ 380,684 $ 123,502 $ 35,181 $ 1,228 $ 540,595 Net income (loss) attributable to noncontrolling interests 12,694 14,904 106 (115 ) 27,589 Business acquisition — — — 11,715 11,715 Purchase of affiliate noncontrolling interest: Payment (fair value portion) — — (8,789 ) — (8,789 ) Change in redemption value — — (25,708 ) — (25,708 ) Distributions (9,892 ) (12,880 ) — (3 ) (22,775 ) Foreign exchange — — (790 ) (43 ) (833 ) Change in estimated redemption value — 3,095 — — 3,095 Balance as of December 31, 2019 $ 383,486 $ 128,621 $ — $ 12,782 $ 524,889 Redeemable noncontrolling interests EnTrust Global Clarion Partners RARE Infrastructure Other Total Balance as of March 31, 2018 $ 386,884 $ 117,272 $ 68,285 $ 1,509 $ 573,950 Net income (loss) attributable to noncontrolling interests 9,752 12,460 1,417 (205 ) 23,424 Distributions (13,475 ) (10,359 ) (1,693 ) (11 ) (25,538 ) Settlement of affiliate noncontrolling interest put: Payment — — (15,547 ) (15,547 ) Change in redemption value — — (12,345 ) (12,345 ) Foreign exchange — — (5,009 ) — (5,009 ) Change in estimated redemption value — 1,037 — — 1,037 Balance as of December 31, 2018 $ 383,161 $ 120,410 $ 35,108 $ 1,293 $ 539,972

Derivatives and Hedging (Tables

Derivatives and Hedging (Tables)	9 Months Ended
Derivatives and Hedging (Tables)	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Schedule of Derivative Assets at Fair Value [Table Text Block]	The following table presents the derivative assets and related offsets, if any: Gross Amounts Not Offset in the Balance Sheet Gross Amounts of Recognized Assets Gross Amounts Offset in the Balance Sheet Net Amount of Derivative Assets Presented in the Balance Sheet Financial Instruments Cash Collateral Net Amount as of Derivative instruments not designated as hedging instruments Currency forward contracts $ 4,092 $ (1,310 ) $ 2,782 $ — $ — $ 2,782 Total return swaps — — — 292 961 1,253 Total derivative instruments not designated as hedging instruments $ 4,092 $ (1,310 ) $ 2,782 $ 292 $ 961 $ 4,035 The following table presents the derivative assets and related offsets, if any: Gross Amounts Not Offset in the Balance Sheet Gross Amounts of Recognized Assets Gross Amounts Offset in the Balance Sheet Net Amount of Derivative Assets Presented in the Balance Sheet Financial Instruments Cash Collateral Net amount as of Derivative instruments not designated as hedging instruments Currency forward contracts $ 3,997 $ (1,874 ) $ 2,123 $ — $ — $ 2,123 Total return swaps — — — 2,060 2,310 4,370 Total derivative instruments not designated as hedging instruments $ 3,997 $ (1,874 ) $ 2,123 $ 2,060 $ 2,310 $ 6,493
Schedule of Derivative Liabilities at Fair Value [Table Text Block]	The following table presents the derivative liabilities and related offsets, if any: Gross Amounts Not Offset in the Balance Sheet Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Balance Sheet Net Amount of Derivative Liabilities Presented in the Balance Sheet Financial Instruments Cash Collateral Net amount as of March 31, 2019 Derivative instruments not designated as hedging instruments Currency forward contracts $ (7,465 ) $ 2,094 $ (5,371 ) $ — $ — $ (5,371 ) Futures contracts relating to: Seed capital investments — — — (1,798 ) 7,640 5,842 Total return swaps — — — (410 ) 1,104 694 Total futures contracts — — — (2,208 ) 8,744 6,536 Total derivative instruments not designated as hedging instruments $ (7,465 ) $ 2,094 $ (5,371 ) $ (2,208 ) $ 8,744 $ 1,165 The following table presents the derivative liabilities and related offsets, if any: Gross Amounts Not Offset in the Balance Sheet Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Balance Sheet Net Amount of Derivative Liabilities Presented in the Balance Sheet Financial Instruments Cash Collateral Net Amount as of Derivative instruments not designated as hedging instruments Currency forward contracts $ (1,426 ) $ 986 $ (440 ) $ — $ — $ (440 ) Futures contracts relating to: Seed capital investments — — — (801 ) 4,809 4,008 Total return swaps — — — (49 ) 366 317 Total future contracts — — — (850 ) 5,175 4,325 Total return swaps (72 ) 890 818 Total derivative instruments not designated as hedging instruments $ (1,426 ) $ 986 $ (440 ) $ (922 ) $ 6,065 $ 4,703
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance	The following table presents gains (losses) recognized in the Consolidated Statements of Income (Loss) on derivative instruments. As described above, the currency forward contracts and futures and forward contracts for seed capital investments included below are economic hedges of interest rate and market risk of certain operating and investing activities of Legg Mason. Three Months Ended December 31, 2019 2018 Income Statement Classification Gains Losses Gains Losses Derivatives not designated as hedging instruments Currency forward contracts relating to: Operating activities Other expense $ 10,325 $ (4,293 ) $ 3,110 $ (5,587 ) Seed capital investments Other non-operating income (expense) 651 (2,219 ) 1,503 (1,116 ) Futures contracts relating to: Seed capital investments Other non-operating income (expense) — (7,351 ) 16,520 (1 ) Total return swaps Other non-operating income (expense) 31 (563 ) 3,121 (467 ) Total return swaps Other non-operating income (expense) 384 (73 ) 203 (832 ) Total gain (loss) from derivatives not designated as hedging instruments $ 11,391 $ (14,499 ) $ 24,457 $ (8,003 ) Nine Months Ended December 31, 2019 2018 Income Statement Classification Gains Losses Gains Losses Derivatives not designated as hedging instruments Currency forward contracts relating to: Operating activities Other expense $ 7,813 $ (8,257 ) $ 9,369 $ (19,366 ) Seed capital investments Other non-operating income (expense) 2,356 (1,233 ) 5,523 (788 ) Futures contracts relating to: Seed capital investments Other non-operating income (expense) 398 (11,223 ) 19,224 (7,066 ) Total return swaps Other non-operating income (expense) 84 (1,441 ) 3,425 (3,418 ) Total return swaps Other non-operating income (expense) 1,885 — 1,869 (938 ) Total gain (loss) from derivatives not designated as hedging instruments $ 12,536 $ (22,154 ) $ 39,410 $ (31,576 )

Strategic Business Initiative_2

Strategic Business Initiative (Tables)	9 Months Ended
Strategic Business Initiative (Tables)	Dec. 31, 2019
Restructuring [Abstract]
Schedule of Restructuring Reserve by Type of Cost [Table Text Block]	The table below presents a summary of changes in the strategic restructuring liability from January 1, 2019 through December 31, 2019, and cumulative charges incurred to date: Compensation and benefits Occupancy Other Total Balance as of January 1, 2019 $ — $ — $ — $ — Accrued charges — 2,090 6,504 8,594 Balance as of March 31, 2019 — 2,090 6,504 8,594 Accrued charges 40,860 4,427 8,059 53,346 Payments (7,992 ) (289 ) (9,886 ) (18,167 ) Balance as of December 31, 2019 $ 32,868 $ 6,228 $ 4,677 $ 43,773 Non-cash charges (1) Three months ended March 31, 2019 $ — $ 758 $ — $ 758 Nine months ended December 31, 2019 12,448 1,503 — 13,951 Total $ 12,448 $ 2,261 $ — $ 14,709 Cumulative charges incurred through December 31, 2019 $ 53,308 $ 8,778 $ 14,563 $ 76,649 (1) Includes stock-based compensation expense and accelerated fixed asset depreciation.
Estimate of Remaining Restructuring Charges to be Incurred [Table Text Block]	The estimates for the remaining strategic restructuring costs expected to be incurred through fiscal 2021 are as follows: Minimum Maximum Compensation and benefits $ 12,000 $ 17,000 Occupancy 16,000 18,000 Other costs 20,000 23,000 Total $ 48,000 $ 58,000 While management expects the total estimated costs to be within the range disclosed, the ultimate nature and timing of the costs may differ from those presented above.

Variable Interest Entities an_2

Variable Interest Entities and Consolidation of Investment Vehicles (Tables)	9 Months Ended
	Dec. 31, 2019
Noncontrolling Interest [Line Items]
Condensed Balance Sheet [Table Text Block]	Consolidating Balance Sheets December 31, 2019 March 31, 2019 Balance Before Consolidation of CIVs and Other (1) CIVs and Other (1) Reclassifications & Eliminations Consolidated Totals Balance Before Consolidation of CIVs and Other (1) CIVs and Other (1) Reclassifications & Eliminations Consolidated Totals Current Assets $ 1,896,010 $ 117,167 $ (37,245 ) $ 1,975,932 $ 1,916,485 $ 144,091 $ (40,720 ) $ 2,019,856 Non-current assets 6,061,015 3,942 (1,171 ) 6,063,786 5,768,265 8,993 (2,992 ) 5,774,266 Total Assets $ 7,957,025 $ 121,109 $ (38,416 ) $ 8,039,718 $ 7,684,750 $ 153,084 $ (43,712 ) $ 7,794,122 Current Liabilities $ 929,495 $ 1,364 $ — $ 930,859 $ 1,104,002 $ 5,742 $ — $ 1,109,744 Non-current liabilities 2,605,229 — — 2,605,229 2,302,463 — — 2,302,463 Total Liabilities 3,534,724 1,364 — 3,536,088 3,406,465 5,742 — 3,412,207 Redeemable Non-controlling interests 587,024 — 81,329 668,353 588,746 — 103,630 692,376 Total Stockholders’ Equity 3,835,277 119,745 (119,745 ) 3,835,277 3,689,539 147,342 (147,342 ) 3,689,539 Total Liabilities and Equity $ 7,957,025 $ 121,109 $ (38,416 ) $ 8,039,718 $ 7,684,750 $ 153,084 $ (43,712 ) $ 7,794,122 (1) Other represents consolidated sponsored investment product VREs that are not designated as CIVs.
Condensed Income Statement [Table Text Block]	Consolidating Statements of Income (Loss) $ 51,439 Three Months Ended December 31, 2019 December 31, 2018 Balance Before (1) CIVs and Other (1) Eliminations Consolidated Totals Balance Before (1) CIVs and Other (1) Eliminations Consolidated Totals Total Operating Revenues $ 753,983 $ — $ (69 ) $ 753,914 $ 704,477 $ — $ (155 ) $ 704,322 Total Operating Expenses 623,817 166 (63 ) 623,920 940,561 308 (120 ) 940,749 Operating Income (Loss) 130,166 (166 ) (6 ) 129,994 (236,084 ) (308 ) (35 ) (236,427 ) Total Non-Operating Income (Expense) (7,300 ) 569 1,404 (5,327 ) (32,158 ) 2,612 (771 ) (30,317 ) Income (Loss) Before Income Tax Provision (Benefit) 122,866 403 1,398 124,667 (268,242 ) 2,304 (806 ) (266,744 ) Income tax provision (benefit) 33,664 — — 33,664 (60,354 ) — — (60,354 ) Net Income (Loss) 89,202 403 1,398 91,003 (207,888 ) 2,304 (806 ) (206,390 ) Less: Net income (loss) attributable to noncontrolling interests 14,427 (245 ) 2,046 16,228 9,000 242 1,256 10,498 Net Income (Loss) Attributable to Legg Mason, Inc. $ 74,775 $ 648 $ (648 ) $ 74,775 $ (216,888 ) $ 2,062 $ (2,062 ) $ (216,888 ) (1) Other represents consolidated sponsored investment products (VREs) that are not designated as CIVs. Nine Months Ended December 31, 2019 December 31, 2018 Balance Before Consolidation of CIVs and Other (1) CIVs and Other (1) Eliminations Consolidated Totals Balance Before (1) CIVs and Other (1) Eliminations Consolidated Totals Total Operating Revenues $ 2,202,888 $ — $ (350 ) $ 2,202,538 $ 2,211,115 $ — $ (461 ) $ 2,210,654 Total Operating Expenses 1,862,253 1,292 87 1,863,632 2,184,807 1,386 (516 ) 2,185,677 Operating Income (Loss) 340,635 (1,292 ) (437 ) 338,906 26,308 (1,386 ) 55 24,977 Total Non-Operating Income (Expense) (40,072 ) 15,625 (4,890 ) (29,337 ) (74,131 ) 2,070 297 (71,764 ) Income (Loss) Before Income Tax Provision 300,563 14,333 (5,327 ) 309,569 (47,823 ) 684 352 (46,787 ) Income tax provision 80,466 — — 80,466 165 — — 165 Net Income (Loss) 220,097 14,333 (5,327 ) 229,103 (47,988 ) 684 352 (46,952 ) Less: Net income (loss) attributable to noncontrolling interests 32,889 721 8,285 41,895 30,007 115 921 31,043 Net Income (Loss) Attributable to Legg Mason, Inc. $ 187,208 $ 13,612 $ (13,612 ) $ 187,208 $ (77,995 ) $ 569 $ (569 ) $ (77,995 )
Consolidated Investment Vehicles [Member]
Noncontrolling Interest [Line Items]
Investment Holdings, Schedule of Investments [Table Text Block]	Because it was determined to be the primary beneficiary of these VIEs, Legg Mason consolidated and designated the following funds as CIVs in the Consolidated Balance Sheets as of: December 31, 2019 March 31, 2019 December 31, 2018 Number of Consolidated Funds Legg Mason Investment in Funds (1) Number of Consolidated Funds Legg Mason Investment in Funds (1) Number of Consolidated Funds Legg Mason Investment in Funds (1) Sponsored investment partnerships 2 $ 9,419 2 $ 11,671 2 $ 12,863 Trust structure foreign mutual funds 6 21,669 7 23,005 8 49,251 Employee trust structure funds 1 4,564 2 6,215 2 6,963 ETFs (2) 2 2,764 3 2,821 2 2,487 Total 11 $ 38,416 14 $ 43,712 14 $ 71,564 (1) Represents Legg Mason's maximum risk of loss, excluding uncollected advisory fees. (2) Under the total return swap arrangements, Legg Mason receives the related investment gains and losses on investments in two of Legg Mason's ETFs with notional amounts totaling $34,907 as of December 31, 2019. See Note 14 for additional information regarding total return swaps.
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table Text Block]	The NAVs used as a practical expedient by CIVs have been provided by the investees and have been derived from the fair values of the underlying investments as of the respective reporting dates. The following table summarizes the nature of these investments and any related liquidation restrictions or other factors, which may impact the ultimate value realized: Fair Value Determined Using NAV As of December 31, 2019 Category of Investment Investment Strategy December 31, 2019 March 31, 2019 Unfunded Commitments Remaining Term Hedge funds Global macro, fixed income, long/short equity, systematic, emerging market, U.S. and European hedge $ 3,619 (1) $ 12,547 n/a n/a n/a - not applicable (1) Redemption restrictions: 22% monthly redemption; 77% quarterly redemption; and 1% are subject to three to five-year lock-up or side pocket provisions.
Legg Mason, Inc
Noncontrolling Interest [Line Items]
Schedule of Variable Interest Entities [Table Text Block]	Legg Mason's carrying value and maximum risk of loss for VIEs in which Legg Mason holds a variable interest, but for which it was not the primary beneficiary, were as follows: As of December 31, 2019 As of March 31, 2019 Equity Interests on the Consolidated Balance Sheet (1) Maximum Risk of Loss (2) Equity Interests on the Consolidated Balance Sheet (1) Maximum Risk of Loss (2) Real Estate Investment Trusts $ 12,312 $ 14,052 $ 10,812 $ 15,241 Other investment funds 31,090 49,646 25,155 45,897 Total $ 43,402 $ 63,698 $ 35,967 $ 61,138 (1) Amounts are related to investments in proprietary and other fund products. (2)

Significant Accounting Polici_3

Significant Accounting Policies Lease Accounting (Details) - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2018	Dec. 31, 2019	Apr. 01, 2019	Mar. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating and Finance Lease, Right-of-Use Asset		$ 295,665	$ 342,418	$ 0
Operating and Finance Lease, Liability		$ 363,288	$ 411,115
Lease reserve liability, vacated space				$ 24,063
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Amount	$ 2,800
Federal State and Local [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	$ 14,100

Significant Accounting Polici_4

Significant Accounting Policies Income Taxes (Details) - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other Tax Expense (Benefit)	$ 2,164	$ 700
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent		5.50%
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Amount		$ 2,800
Other Expense [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Amount		$ 1,100

Fair Values of Assets and Lia_3

Fair Values of Assets and Liabilities by Level (Details 1) - USD ($)	Dec. 31, 2019	Mar. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investments	$ 27,051,000	$ 28,160,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability	0	0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	0	0
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	429,557,000	556,231,000
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	3,074,000	4,183,000
Assets, Fair Value Disclosure	779,374,000	889,978,000
Business Combination, Contingent Consideration, Liability	0	0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	(1,362,000)	(7,579,000)
Financial Liabilities Fair Value Disclosure	(1,362,000)	(7,579,000)
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	13,098,000	20,160,000
Assets, Fair Value Disclosure	44,550,000	52,977,000
Business Combination, Contingent Consideration, Liability	0	0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	0	0
Financial Liabilities Fair Value Disclosure	0	0
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	91,305,000	55,698,000
Business Combination, Contingent Consideration, Liability	(3,376,000)	(1,415,000)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	0	0
Financial Liabilities Fair Value Disclosure	(3,376,000)	(1,415,000)
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Fair Value Measured at Net Asset Value Per Share [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	30,843,000	34,293,000
Financial Liabilities Fair Value Disclosure	0	0
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Fair Value, Inputs, Level 1, 2 and 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	442,655,000	576,391,000
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	3,074,000	4,183,000
Assets, Fair Value Disclosure	946,072,000	1,032,946,000
Business Combination, Contingent Consideration, Liability	(3,376,000)	(1,415,000)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	(1,362,000)	(7,579,000)
Financial Liabilities Fair Value Disclosure	(4,738,000)	(8,994,000)
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Other Noncurrent Assets [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI and without Readily Determinable Fair Value	73,000	74,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Other Noncurrent Assets [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI and without Readily Determinable Fair Value	26,366,000	12,171,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Other Noncurrent Assets [Member] \| Fair Value, Inputs, Level 1, 2 and 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI and without Readily Determinable Fair Value	26,439,000	12,245,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Proprietary Funds [Member] \| Current Investments [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	73,738,000	98,276,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Proprietary Funds [Member] \| Current Investments [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	29,352,000	30,601,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Proprietary Funds [Member] \| Current Investments [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	21,546,000	1,455,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Proprietary Funds [Member] \| Current Investments [Member] \| Fair Value Measured at Net Asset Value Per Share [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	1,650,000	2,183,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Proprietary Funds [Member] \| Current Investments [Member] \| Fair Value, Inputs, Level 1, 2 and 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	126,286,000	132,515,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Proprietary Funds [Member] \| Other Noncurrent Assets [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investments, Fair Value Disclosure	43,340,000	40,854,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Proprietary Funds [Member] \| Other Noncurrent Assets [Member] \| Fair Value Measured at Net Asset Value Per Share [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investments, Fair Value Disclosure	12,035,000	10,675,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Proprietary Funds [Member] \| Other Noncurrent Assets [Member] \| Fair Value, Inputs, Level 1, 2 and 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investments, Fair Value Disclosure	55,375,000	51,529,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Long Term Incentive Compensation Plans [Member] \| Current Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investments, Fair Value Disclosure	7,625,000	11,184,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Long Term Incentive Compensation Plans [Member] \| Current Investments [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	258,040,000	211,802,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Long Term Incentive Compensation Plans [Member] \| Current Investments [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	0	0
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Long Term Incentive Compensation Plans [Member] \| Current Investments [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	0	0
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Long Term Incentive Compensation Plans [Member] \| Current Investments [Member] \| Fair Value Measured at Net Asset Value Per Share [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	0	0
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Long Term Incentive Compensation Plans [Member] \| Current Investments [Member] \| Fair Value, Inputs, Level 1, 2 and 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	258,040,000	211,802,000
Equity Method Investments, Fair Value Disclosure	7,625,000	11,184,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Other Investments [Member] \| Current Investments [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	14,965,000	19,486,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Other Investments [Member] \| Current Investments [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	2,027,000	2,142,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Other Investments [Member] \| Current Investments [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	0	0
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Other Investments [Member] \| Current Investments [Member] \| Fair Value Measured at Net Asset Value Per Share [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	0	0
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Other Investments [Member] \| Current Investments [Member] \| Fair Value, Inputs, Level 1, 2 and 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	16,992,000	21,628,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Other Investments [Member] \| Other Noncurrent Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investments, Fair Value Disclosure	9,533,000	10,251,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Other Investments [Member] \| Other Noncurrent Assets [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investments, Fair Value Disclosure	53,000	1,218,000
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Other Investments [Member] \| Other Noncurrent Assets [Member] \| Fair Value, Inputs, Level 1, 2 and 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investments, Fair Value Disclosure	$ 9,586,000	$ 11,469,000

Fair Values of Assets and Lia_4

Fair Values of Assets and Liabilities Unrealized and Realized Gain (Loss) on Equity Investments (Details) - Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI, Gain (Loss)	$ 25,698	$ (34,793)	$ 30,938	$ (25,246)
Equity Securities, FV-NI, Unrealized Gain (Loss)	$ 21,441	$ (38,741)	$ 13,765	$ (51,313)

Fair Values of Assets and Lia_5

Fair Values of Assets and Liabilities Information Regarding Proprietary Fund Products (Details 2) $ in Thousands	Dec. 31, 2019USD ($)	Mar. 31, 2019USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percentage of total seed investment balance comprised of funds individually in excess of one million dollars	90.00%
Proprietary Funds [Member] \| Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	$ 220,077	$ 227,756
Number of Proprietary Fund Products with Seed Capital Investment in Excess of One Million Dollars	45	52
Variable Interest Entity, Primary Beneficiary [Member] \| Proprietary Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	$ 38,416	$ 43,712

Changes in Level 3 Assets and L

Changes in Level 3 Assets and Liabilities (Details 3) - Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, Beginning of Period	$ 87,618	$ 51,160	$ 55,698	$ 41,918
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	3,780	6,579	38,139	16,196
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(3,282)	(1,899)	(5,849)	(4,301)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Period Increase (Decrease)	1,843	273	3,317	2,300
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, End of Period	91,305	56,113	91,305	56,113
Proprietary Funds [Member] \| Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, Beginning of Period	20,200	1,394	1,455	1,242
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	1,000	0	21,200	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		0	(1,457)	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Period Increase (Decrease)	346	(128)	348	24
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, End of Period	21,546	1,266	21,546	1,266
Proprietary Funds [Member] \| Equity Method Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, Beginning of Period	43,252	37,020	40,854	33,725
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	283	5,516	2,621	9,483
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(2,073)	(1,880)	(3,045)	(4,280)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Period Increase (Decrease)	1,878	398	2,910	2,126
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, End of Period	43,340	41,054	43,340	41,054
Other Investments [Member] \| Equity Method Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, Beginning of Period	1,297	1,840	1,218	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	0	0	0	1,650
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(1,209)	(19)	(1,222)	(19)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Period Increase (Decrease)	(35)	0	57	190
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, End of Period	53	1,821	53	1,821
Other Investments [Member] \| Cost-method Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, Beginning of Period	22,869	10,906	12,171	6,951
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	3,497	1,063	14,318	5,063
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	0	0	(125)	(2)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Period Increase (Decrease)	0	3	2	(40)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, End of Period	26,366	11,972	26,366	11,972
Contingent Consideration Liability Fair Value [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value, Beginning of Period	(3,625)	(1,900)	(1,415)	(5,607)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases	0		(3,389)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	250	0	250	4,319
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Period Increase (Decrease)	(1)	0	1,178	(612)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value, End of Period	(3,376)	(1,900)	(3,376)	(1,900)
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss)	$ 1,776	$ 275	$ 4,089	$ 2,336

Fair Values of Assets and Lia_6

Fair Values of Assets and Liabilities NAV Investments (Details 4) - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2019	Mar. 31, 2019
Other Investments [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments Remaining Term, High End of Range	10.0
Fair Value Measured at Net Asset Value Per Share [Member] \| Funds-Of-Hedge Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of Monthly Redemption	14.00%
Percentage of Quarterly Redemption	1.00%
Percentage Not Currently Redeemable	85.00%
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	$ 5,698
Alternative Investment	30,843	$ 34,293
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Funds-Of-Hedge Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investment	11,905	9,910
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Hedge Funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investment	1,049	1,515
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Private Equity Funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	5,698
Alternative Investment	10,244	11,636
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Long Term Incentive Compensation Plans [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investment	7,625	11,185
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] \| Other Investments [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investment	$ 20	$ 47

Acquisitions Gramercy (Details)

Acquisitions Gramercy (Details) € in Thousands, $ in Thousands	Apr. 10, 2019USD ($)	Dec. 31, 2019EUR (€)	Dec. 31, 2019USD ($)	Dec. 31, 2019USD ($)	Apr. 10, 2019EUR (€)	Apr. 10, 2019USD ($)
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life		5 years 7 months 6 days
Gramercy [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life	8 years
Payments to Acquire Businesses, Gross			$ 10,247
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High		€ 3,315		$ 3,721	€ 3,315	$ 3,735
Finite-lived Intangible Assets Acquired	$ 5,876
Goodwill, Acquired During Period	$ 20,196
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value						11,715
Business Combination, Contingent Consideration, Liability						$ 3,389

Schedule of Fixed Assets (Detai

Schedule of Fixed Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Fixed assets:
Total cost	$ 652,330	$ 642,107
Less: accumulated depreciation and amortization	(513,495)	(492,118)
Fixed assets, net	138,835	149,989
Software
Fixed assets:
Total cost	276,096	269,944
Leasehold improvements
Fixed assets:
Total cost	213,439	212,742
Equipment
Fixed assets:
Total cost	$ 162,795	$ 159,421

Fixed Assets Depreciation and A

Fixed Assets Depreciation and Amortization Expense (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment
Accelerated Depreciation, Other	$ 1,603
Property, Plant and Equipment [Member]
Property, Plant and Equipment
Depreciation and amortization	$ 12,252	$ 11,799	$ 34,098	$ 35,659

Components Intangible Assets (D

Components Intangible Assets (Details 1) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2019
Finite-Lived and Indefinite-lived Intangible Assets
Cost		$ 372,808		$ 366,930
Accumulated amortization		(257,410)		(240,488)
Total		$ 115,398		126,442
Schedule of Finite-lived and Indefinite-lived Intangible Assets by Major Class [Table Text Block]		The following table reflects the components of intangible assets as of: December 31, 2019 March 31, 2019 Amortizable intangible asset management contracts and other Cost $ 372,808 $ 366,930 Accumulated amortization (257,410 ) (240,488 ) Net (1) 115,398 126,442 Indefinite–life intangible assets U.S. domestic mutual fund management contracts 2,106,351 2,106,351 Clarion Partners fund management contracts 505,200 505,200 EnTrust Global fund management contracts 126,804 126,804 Other fund management contracts 475,069 473,360 Trade names 48,695 48,602 3,262,119 3,260,317 Intangible assets, net $ 3,377,517 $ 3,386,759 (1) As of December 31, 2019, includes $5,305 related to the acquisition of Gramercy by Clarion Partners. See Note 4 for additional information.
Indefinite-life intangible assets		$ 3,262,119		3,260,317
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount		22.00%
U.S. Domestic Mutual Fund Management Contracts
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets		$ 2,106,351		2,106,351
Other Fund Management Contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets		475,069		473,360
Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets		48,695		48,602
Consolidated Legg Mason, Inc.
Finite-Lived and Indefinite-lived Intangible Assets
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)	$ 365,200		$ 365,200
Intangible assets, net		3,377,517		3,386,759
Consolidated Legg Mason, Inc. \| Fund management contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)	358,800
EnTrust Global [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Other Indefinite-lived Intangible Assets	401,404	126,804	401,404
Indefinite-Lived Trade Names	28,500	10,300	28,500
EnTrust Global [Member] \| Fund management contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets		$ 126,804		126,804
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount		10.00%
EnTrust Global [Member] \| Other Fund Management Contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Asset Impairment Charges			274,600
EnTrust Global [Member] \| Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount		6.00%
Asset Impairment Charges			18,200
Clarion Partners [Member] \| Fund management contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets		$ 505,200		$ 505,200
RARE Infrastructure, Ltd [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Other Indefinite-lived Intangible Assets	120,800		120,800
Indefinite-Lived Trade Names	2,800		2,800
RARE Infrastructure, Ltd [Member] \| Other Fund Management Contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Asset Impairment Charges			65,000
RARE Infrastructure, Ltd [Member] \| Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Asset Impairment Charges			1,000
RARE Infrastructure, Ltd [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Total	$ 6,900		$ 6,900
Gramercy [Member] \| Clarion Partners [Member] \| Fund management contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets		$ 5,305
Cash Flow Growth Rate [Member] \| Maximum [Member] \| RARE Infrastructure, Ltd [Member] \| Fund management contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	4.90%		4.90%
Cash Flow Growth Rate [Member] \| Maximum [Member] \| RARE Infrastructure, Ltd [Member] \| Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	4.60%		4.60%
Cash Flow Growth Rate [Member] \| Maximum [Member] \| EnTrust Global [Member] \| Fund management contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	3.90%		3.90%
Cash Flow Growth Rate [Member] \| Maximum [Member] \| EnTrust Global [Member] \| Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	4.60%		4.60%
Cash Flow Growth Rate [Member] \| Weighted Average [Member] \| RARE Infrastructure, Ltd [Member] \| Fund management contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	4.80%		4.80%
Cash Flow Growth Rate [Member] \| Weighted Average [Member] \| RARE Infrastructure, Ltd [Member] \| Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	4.20%		4.20%
Cash Flow Growth Rate [Member] \| Weighted Average [Member] \| EnTrust Global [Member] \| Fund management contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	3.00%		3.00%
Cash Flow Growth Rate [Member] \| Weighted Average [Member] \| EnTrust Global [Member] \| Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	3.90%		3.90%
Cash Flow Growth Rate [Member] \| Minimum [Member] \| RARE Infrastructure, Ltd [Member] \| Fund management contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	4.40%		4.40%
Cash Flow Growth Rate [Member] \| Minimum [Member] \| RARE Infrastructure, Ltd [Member] \| Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	0.90%		0.90%
Cash Flow Growth Rate [Member] \| Minimum [Member] \| EnTrust Global [Member] \| Fund management contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	(19.40%)		(19.40%)
Cash Flow Growth Rate [Member] \| Minimum [Member] \| EnTrust Global [Member] \| Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	0.00%		0.00%
Measurement Input, Discount Rate [Member] \| RARE Infrastructure, Ltd [Member] \| Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	16.50%		16.50%
Measurement Input, Discount Rate [Member] \| EnTrust Global [Member] \| Fund management contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	17.00%		17.00%
Measurement Input, Discount Rate [Member] \| EnTrust Global [Member] \| Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	16.50%		16.50%
Measurement Input, Long-term Revenue Growth Rate [Member] \| RARE Infrastructure, Ltd [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Finite-lived Intangible Assets, Measurement Input	7.00%		7.00%
Royalty [Member] \| RARE Infrastructure, Ltd [Member] \| Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	1.00%		1.00%
Royalty [Member] \| EnTrust Global [Member] \| Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-lived Intangible Assets, Measurement Input	1.00%		1.00%

Schedule of Goodwill Carrying V

Schedule of Goodwill Carrying Value Rollfoward (Details 4) $ in Thousands	9 Months Ended
	Dec. 31, 2019USD ($)
Goodwill
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	22.00%
Goodwill Gross Value [Member]
Goodwill
Goodwill, Gross, Beginning of Period	$ 3,045,454
Impact of excess tax basis amortization	(8,256)
Other, including changes in foreign exchange rates	603
Goodwill, Acquired During Period	20,196
Goodwill, Gross, End of Period	3,057,997
Goodwill Accumulated Impairment [Member]
Goodwill
Accumulated Impairment, Beginning of Period	(1,161,900)
Accumulated Impairment, End of Period	(1,161,900)
Goodwill Net Value [Member]
Goodwill
Goodwill, Beginning of Period	1,883,554
Impact of excess tax basis amortization	(8,256)
Other, including changes in foreign exchange rates	603
Goodwill, Acquired During Period	20,196
Goodwill, End of Period	$ 1,896,097

Schedule of Remaining Intangibl

Schedule of Remaining Intangible Amortization (Details 3) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	Mar. 31, 2019
Finite-Lived Intangible Assets Future Amortization Expense [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years 7 months 6 days
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year	$ 5,640
Finite-Lived Intangible Assets, Amortization Expense, Year Two	21,834
Finite-Lived Intangible Assets, Amortization Expense, Year Three	21,485
Finite-Lived Intangible Assets, Amortization Expense, Year Four	20,725
Finite-Lived Intangible Assets, Amortization Expense, Year Five	19,896
Thereafter	25,818
Total	$ 115,398	$ 126,442

Long-Term Debt Schedule of Curr

Long-Term Debt Schedule of Current Value of Long-term Debt (Details) - USD ($) $ in Thousands	Jul. 15, 2019	Dec. 31, 2019	Mar. 31, 2019
Debt Instrument [Line Items]
Long-term Debt, Current Maturities		$ 0	$ (250,301)
Long-term debt, net		1,972,413	1,971,451
Long-term Debt, Maturities, Repayments of Principal after Year Five		2,000,000
Long-term Debt, Fair Value		2,170,660
Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Debt Instrument [Line Items]
Long-term Debt		1,972,413	2,221,752
Debt Instrument, Unamortized Discount (Premium), Net		(2,732)
Unamortized Debt Issuance Expense		30,319
Long-term Debt, Gross		2,000,000
Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member] \| 2.7% Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt			250,301
Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member] \| 3.95% Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt		248,917	248,738
Debt Instrument, Unamortized Discount		206
Unamortized Debt Issuance Expense		877
Long-term Debt, Gross		250,000
Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member] \| 4.75% Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt		447,786	447,521
Debt Instrument, Unamortized Premium		0
Unamortized Debt Issuance Expense		2,214
Long-term Debt, Gross		450,000
Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member] \| 5.625% Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt		548,079	548,020
Debt Instrument, Unamortized Premium		(2,938)
Unamortized Debt Issuance Expense		4,859
Long-term Debt, Gross		550,000
Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member] \| 6.375% Junior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt		242,614	242,461
Debt Instrument, Unamortized Premium		0
Unamortized Debt Issuance Expense		7,386
Long-term Debt, Gross		250,000
Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member] \| 5.45% Junior Subordinated Notes [Member]
Debt Instrument [Line Items]
Long-term Debt		485,017	$ 484,711
Debt Instrument, Unamortized Premium		0
Unamortized Debt Issuance Expense		14,983
Long-term Debt, Gross		500,000
Current Portion of Long-Term Debt \| Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount		0
Unamortized Debt Issuance Expense		0
Long-term Debt, Gross		0
Long-term Debt \| Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount (Premium), Net		(2,732)
Unamortized Debt Issuance Expense		30,319
Long-term Debt, Gross		$ 2,000,000
2.7% Senior Notes [Member]
Debt Instrument [Line Items]
Repayments of Debt	$ 250,000
Debt Instrument, Interest Rate, Stated Percentage		2.70%

Income Taxes Effective Tax Rate

Income Taxes Effective Tax Rate Reconciliation (Details)	9 Months Ended
Income Taxes Effective Tax Rate Reconciliation (Details)	Dec. 31, 2018
Reconciliation of Tax Rate [Line Items]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent	5.50%

Leases Summary Lease Detail (De

Leases Summary Lease Detail (Details) number in Thousands, $ in Thousands	9 Months Ended
	Dec. 31, 2019	Mar. 31, 2019USD ($)
Lease Disclosures [Abstract]
Square Footage Leased	1,500
Lessee, Operating Lease, Term of Contract	19 years
Lessee, Operating Lease, Option to Extend, Period	15 years
Lessee, Option to Terminate, Period	7 years
Lease reserve liability, vacated space		$ 24,063

Leases Schedule of Balance Shee

Leases Schedule of Balance Sheet Information Related to Operating and Finance Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Schedule of Leased Assets [Line Items]
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ (513,495)	$ (492,118)
Operating Lease, Right-of-Use Asset	294,174
Operating Lease, Liability	361,921
Finance Lease, Right-of-Use Asset, Gross	2,134
Finance Lease, Right-of-Use Asset	1,491
Finance Lease, Liability	1,367
Right-of-Use Asset [Member]
Schedule of Leased Assets [Line Items]
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ (643)

Leases Components of Lease Expe

Leases Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment
Operating Lease, Expense		$ 20,445		$ 64,649
Operating lease cost	$ 25,361		$ 67,172
Finance Lease, Right-of-Use Asset, Amortization	251		737
Finance Lease, Interest Expense	11		36
Finance Lease Cost, Total	262		773
Short-term Lease, Cost	1,190		4,885
Variable Lease, Cost	6,599		17,788
Sublease Income	(6,091)		(18,624)
Lease, Cost	27,321		71,994
Leasehold Improvements [Member]
Property, Plant and Equipment
Amortization	$ 5,292	$ 3,632	$ 13,123	$ 11,684

Leases Lessee Lease Liability P

Leases Lessee Lease Liability Payments Due (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Apr. 01, 2019	Mar. 31, 2019
Leases [Abstract]
Operating Leases, Future Minimum Payments, Remainder of Fiscal Year	$ 23,181
Operating Leases, Future Minimum Payments, Due in Two Years	88,048		$ 86,095
Operating Leases, Future Minimum Payments, Due in Three Years	86,385		84,485
Operating Leases, Future Minimum Payments, Due in Four Years	84,530		83,425
Operating Leases, Future Minimum Payments, Due in Five Years	70,210		72,192
Operating Leases, Future Minimum Payments, Due Thereafter	46,472		$ 47,240
Lessee, Operating Lease, Liability, Payments, Due	398,826
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(36,905)
Operating Lease, Liability	361,921
Finance Lease, Liability, Payments, Remainder of Fiscal Year	263
Finance Lease, Liability, Payments, Due Year Two	714
Finance Lease, Liability, Payments, Due Year Three	271
Finance Lease, Liability, Payments, Due Year Four	131
Finance Lease, Liability, Payments, Due Year Five	35
Finance Lease, Liability, Payments, Due after Year Five	5
Finance Lease, Liability, Payment, Due	1,419
Finance Lease, Liability, Undiscounted Excess Amount	(52)
Finance Lease, Liability	1,367
Lease Liability Payments Remainder of Fiscal Year	23,444
Lease Liability Payments Due Year Two	88,762
Lease Liability Payments Due Year Three	86,656
Lease Liability Payments Due Year Four	84,661
Lease Liability Payments Due Year Five	70,245
Lease Liability Payments Due After Year Five	46,477
Lease Liability Payment Due	400,245
Lease Liability Undiscounted Excess Amount	(36,957)
Operating and Finance Lease, Liability	$ 363,288	$ 411,115

Leases Lease Term and Discount

Leases Lease Term and Discount Rate (Details)	Dec. 31, 2019
Leases [Abstract]
Operating Lease, Weighted Average Remaining Lease Term	4 years 9 months 18 days
Finance Lease, Weighted Average Remaining Lease Term	2 years
Operating Lease, Weighted Average Discount Rate, Percent	4.00%
Finance Lease, Weighted Average Discount Rate, Percent	3.10%

Leases Schedule of Supplemental

Leases Schedule of Supplemental Information Related to Operating and Finance Leases (Details) $ in Thousands	9 Months Ended
	Dec. 31, 2019USD ($)
Leases [Abstract]
Operating Lease, Payments	$ 64,470
Finance Lease, Principal Payments	$ 727

Leases Future Minimum Lease Pay

Leases Future Minimum Lease Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals		$ 105,193
Operating Leases, Future Minimum Payments Due, Next Twelve Months		90,667
Operating Leases, Future Minimum Payments, Due in Two Years	$ 88,048	86,095
Operating Leases, Future Minimum Payments, Due in Three Years	86,385	84,485
Operating Leases, Future Minimum Payments, Due in Four Years	84,530	83,425
Operating Leases, Future Minimum Payments, Due in Five Years	70,210	72,192
Operating Leases, Future Minimum Payments, Due Thereafter	$ 46,472	47,240
Operating Leases, Future Minimum Payments Due		$ 464,104

Leases ROU Impairment (Details)

Leases ROU Impairment (Details) $ in Thousands	3 Months Ended
Leases ROU Impairment (Details) $ in Thousands	Dec. 31, 2019USD ($)
Leases [Abstract]
Operating Lease, Impairment Loss	$ 4,328
Accelerated Depreciation, Other	$ 1,603

Commitments and Contingencies I

Commitments and Contingencies Information Regarding Other Commitments (Details 1) $ in Thousands	Dec. 31, 2019USD ($)
Investment In Limited Partnerships [Member]
Other Commitments [Line Items]
Other Commitment	$ 17,588
Clarion Partners [Member]
Other Commitments [Line Items]
Other Commitment	$ 100,000

Commitments and Contingencies F

Commitments and Contingencies Future Commitments For Service Contracts (Details 2) - Service Agreements [Member] $ in Thousands	Dec. 31, 2019USD ($)
Other Commitments [Line Items]
Other Commitment	$ 102,794
Other Commitments, Future Minimum Payments, Remainder of Fiscal Year	20,087
Other Commitment, Due in Second Year	39,348
Other Commitment, Due in Third Year	21,534
Other Commitment, Due in Fourth and Fifth Year	$ 21,825

Commitments and Contingencies C

Commitments and Contingencies Commitments Related to Noncontrolling Interests (Details) $ in Thousands	9 Months Ended
	Dec. 31, 2019USD ($)
Other Commitments [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount, End of Period	$ 668,353
Noncontrolling Interest [Member]
Other Commitments [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount, End of Period	524,889
Management Equity Plan [Member]
Other Commitments [Line Items]
Deferred Compensation Arrangement with Individual, Fair Value of Shares Issued	$ 82,495

Commitments and Contingencies_2

Commitments and Contingencies Commitments and Contingencies related to Acquisitions (Details) € in Thousands, $ in Thousands	Dec. 31, 2019EUR (€)	Dec. 31, 2019USD ($)	Apr. 10, 2019EUR (€)	Apr. 10, 2019USD ($)	Mar. 31, 2019USD ($)
Business Acquisition, Contingent Consideration [Line Items]
Business Combination, Contingent Consideration, Liability, Noncurrent		$ 3,376			$ 1,415
Gramercy [Member]
Business Acquisition, Contingent Consideration [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	€ 3,315	$ 3,721	€ 3,315	$ 3,735

Stock Based Compensation Summar

Stock Based Compensation Summary (Details) shares in Thousands	3 Months Ended	9 Months Ended
	Dec. 31, 2019shares	Dec. 31, 2019shares
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	6,292	6,292
Share-based Compensation Arrangement by Share-based Payment Award Granted Price as Percentage of Fair Market Value Minimum	100.00%
Minimum [Member] \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		4 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		8 years
Maximum [Member] \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		10 years

Stock-Based Compensation Compen

Stock-Based Compensation Compensation Expense (Details 1) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Payment Arrangement, Expense	$ 15,426	$ 14,750	$ 57,949	$ 49,975
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Payment Arrangement, Expense	12,025	11,668	43,507	38,707
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Payment Arrangement, Expense	728	1,057	2,643	3,513
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Employee Stock Ownership Plan (ESOP), Compensation Expense	77	96	415	480
Rabbi trust [Domain]
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Payment Arrangement, Expense	9	8	26	23
Subsidiaries [Member] \| Management Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Deferred Compensation Arrangement with Individual, Compensation Expense	23	719	1,670	2,213
Director [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Payment Arrangement, Expense	0	0	1,000	1,025
Key Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Deferred Compensation Arrangement with Individual, Compensation Expense	$ 2,564	$ 1,202	$ 8,688	$ 4,014

Stock-Based Compensation Restri

Stock-Based Compensation Restricted Stock and Restricted Stock Unit Transactions (Details 2) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	9 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Payment Arrangement, Accelerated Cost	$ 0
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	2,903	2,903	3,084	3,045	3,299
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 36.43	$ 36.43	$ 37.80	$ 37.76	$ 38.09
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		1,205	1,179
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 35.50	$ 39.05
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		(1,288)	(1,286)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value		$ 38.70	$ 39.73
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period		(59)	(108)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value		$ 36.88	$ 37.62
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount	$ 63,186	$ 63,186
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms	1 year 7 months 6 days

Stock-Based Compensation Schedu

Stock-Based Compensation Schedule of Outstanding Stock Options (Details 3) - Restricted Stock [Member] - $ / shares shares in Thousands	9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	3,666	4,153	4,115	4,437
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 39.65	$ 38.99	$ 39.05	$ 38.78
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	(369)	(189)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 31.55	$ 31.62
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(80)	(95)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 46.18	$ 43.92

Stock-Based Compensation Stock

Stock-Based Compensation Stock Options Excercisable (Details 4) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 31, 2019USD ($)$ / sharesshares
Equity Option [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Outstanding	3,262
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares	404
Share-based Payment Arrangement, Option, Exercise Price Range, Exercisable, Weighted Average Exercise Price \| $ / shares	$ 40.23
Share-based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount \| $	$ 920
Employee Stock Option
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	3 years
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition	10 months 24 days

Stock-Based Compensation Manage

Stock-Based Compensation Management Equity Plans (Details 5) - Management Equity Plan [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred Compensation Arrangement with Individual, Fair Value of Shares Issued			$ 82,495
Clarion Partners [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Profits interests equity plan participation percentage	15.00%
Deferred Compensation Arrangement with Individual, Fair Value of Shares Issued	$ 12,100
Royce [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred Compensation Arrangement with Individual, Fair Value of Shares Issued	$ 10,800
ClearBridge Investments [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Profits interests equity plan participation percentage	15.00%
Deferred Compensation Arrangement with Individual, Compensation Expense	$ 16,000
Deferred Compensation Arrangement with Individual, Fair Value of Shares Issued			59,595
ClearBridge Investments [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred Compensation Arrangement with Individual, Compensation Expense	23	$ 719	1,670	$ 2,213
Subsidiaries [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred Compensation Arrangement with Individual, Compensation Expense	23	$ 719	$ 1,670	$ 2,213
ClearBridge Management Equity Plan [Member] \| ClearBridge Investments [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred Compensation Arrangement with Individual, Compensation Expense	$ 1,600

Stock-Based Compensation Non-em

Stock-Based Compensation Non-employee Directors Equity Plan (Details 6) - Restricted Stock [Member] - shares shares in Thousands	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	2,903	3,045	3,084	3,299
Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	34		98

Stock-Based Compensation Perfor

Stock-Based Compensation Performance Share Grants (Details 7) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended			9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2018
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	168	163
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Outstanding	$ 6,334			$ 6,334		$ 5,820
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value				$ 37.63	$ 35.67
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	4.41%	3.49%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	2.11%	2.71%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate	23.96%	26.14%
Performance Shares [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 21.63	$ 18.08
Performance Shares [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 45.63	$ 44.46
Clarion Partners [Member] \| Long Term Incentive Compensation Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Deferred Compensation Arrangement with Individual, Shares Issued			716
Stock Issued During Period, Value, Restricted Stock Award, Gross			$ 11,121

Revenue Revenue by Asset Class

Revenue Revenue by Asset Class (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total Operating Revenues	$ 753,914	$ 704,322	$ 2,202,538	$ 2,210,654
Equity AUM [Member]
Disaggregation of Revenue [Line Items]
Total Operating Revenues	293,130	296,738	875,965	931,350
Fixed Income AUM [Member]
Disaggregation of Revenue [Line Items]
Total Operating Revenues	299,121	275,559	873,687	855,343
Alternative AUM [Member]
Disaggregation of Revenue [Line Items]
Total Operating Revenues	139,061	110,390	384,068	361,239
Liquidity AUM [Member]
Disaggregation of Revenue [Line Items]
Total Operating Revenues	$ 22,602	$ 21,635	$ 68,818	$ 62,722

Revenue Revenue by Geographic L

Revenue Revenue by Geographic Location (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total Operating Revenues	$ 753,914	$ 704,322	$ 2,202,538	$ 2,210,654
UNITED STATES
Disaggregation of Revenue [Line Items]
Total Operating Revenues	583,080	547,696	1,730,546	1,711,426
UNITED KINGDOM
Disaggregation of Revenue [Line Items]
Total Operating Revenues	56,264	35,142	121,303	111,739
Non-US [Member]
Disaggregation of Revenue [Line Items]
Total Operating Revenues	$ 114,570	$ 121,484	$ 350,689	$ 387,489

Revenue Revenue (Details)

Revenue Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Revenue Revenue (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2019
Capitalized Contract Cost, Net, Current	$ 8,565		$ 8,565		$ 8,126
Capitalized Contract Cost, Net, Noncurrent	10,234		10,234		$ 10,147
Capitalized Contract Cost, Amortization	$ 2,417	$ 2,305	$ 7,050	$ 6,964

Earnings Per Share Schedule of

Earnings Per Share Schedule of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Consolidated Legg Mason, Inc.
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted Average Number of Shares Outstanding, Basic	86,878	85,537	86,666	85,381
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	287	0	266	0
Weighted Average Number of Shares Outstanding, Diluted	87,165	85,537	86,932	85,381
Net Income Attributable to Legg Mason, Inc.	$ 74,775	$ (216,888)	$ 187,208	$ (77,995)
Basic (in dollars per share)	$ 0.83	$ (2.55)	$ 2.09	$ (0.95)
Earnings Per Share, Diluted	$ 0.83	$ (2.55)	$ 2.08	$ (0.95)
Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net Income Attributable to Legg Mason, Inc.	$ 74,775	$ (216,888)	$ 187,208	$ (77,995)
Participating Securities, Distributed and Undistributed Earnings (Loss), Diluted	2,428	1,049	6,138	3,190
Net Income (Loss) Available to Common Stockholders, Diluted	$ 72,347	$ (217,937)	$ 181,070	$ (81,185)
Restricted Stock [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights	2,935	3,104	2,919	3,104

Earnings Per Share Information

Earnings Per Share Information about Dilutive and Anti-Dilute Shares (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Antidilutive shares due to proceeds from exercising exceeded price of shares [Domain]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,860		1,995
Antidilutive shares due to loss [Domain]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		56		143
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights	2,935	3,104	2,919	3,104

Noncontrolling Interests Income

Noncontrolling Interests Income Attributable to NCI Reconciliation Schedule (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Noncontrolling Interest [Line Items]
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest	$ 14,266	$ 8,852	$ 36,595	$ 24,460
Net Income (Loss) Attributable to Noncontrolling Interest	16,228	10,498	41,895	31,043
Royce [Member]
Noncontrolling Interest [Line Items]
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	$ 1,962	$ 1,646	$ 5,300	$ 6,583

Noncontrolling Interests Roll_2

Noncontrolling Interests Rollforward (Details) - USD ($) $ in Thousands	Jul. 02, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount, Beginning of Period			$ 676,950	$ 692,376	$ 732,295
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest		$ 14,266	8,852	36,595	24,460
Noncontrolling Interest, Increase from Business Combination				11,715
Proceeds from (Payments to) Noncontrolling Interests				(31,307)	(36,328)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests				(8,789)	(15,547)
Noncontrolling Interest, Change in Redemption Value				17,079	14,962
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders				(22,775)	(25,538)
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange				(833)	(5,009)
Redeemable Noncontrolling Interest, Equity, Carrying Amount, End of Period		668,353		668,353
CIVs and Other
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount, Beginning of Period			89,755	103,630	125,047
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest				9,006	1,036
Proceeds from (Payments to) Noncontrolling Interests				(31,307)	(36,328)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders				0	0
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange				0	0
Vesting/Change in Estimated Redemption Value				0	0
Redeemable Noncontrolling Interest, Equity, Carrying Amount, End of Period		81,329		81,329
Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount, Beginning of Period			539,972	540,595	573,950
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest				27,589	23,424
Noncontrolling Interest, Increase from Business Combination				11,715
Proceeds from (Payments to) Noncontrolling Interests				0	0
Noncontrolling Interest, Change in Redemption Value				3,095	1,037
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders				(22,775)	(25,538)
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange				(833)	(5,009)
Redeemable Noncontrolling Interest, Equity, Carrying Amount, End of Period		524,889	539,972	524,889	539,972
Management Equity Plan [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount, Beginning of Period			47,223	48,151	33,298
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest				0	0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders				0	0
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange				0	0
Vesting/Change in Estimated Redemption Value				13,984	13,925
Redeemable Noncontrolling Interest, Equity, Carrying Amount, End of Period		62,135		62,135
RARE Infrastructure, Ltd [Member] \| Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount, Beginning of Period				35,181	68,285
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest				106	1,417
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests				(8,789)	(15,547)
Noncontrolling Interest, Change in Redemption Value	$ 12,345	(25,708)		(25,708)	(12,345)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders				0	(1,693)
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange				(790)	(5,009)
Redeemable Noncontrolling Interest, Equity, Carrying Amount, End of Period		0	35,108	0	35,108
Royce [Member]
Noncontrolling Interest [Line Items]
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest		1,962	1,646	5,300	6,583
Management Equity Plan [Member] \| Royce [Member]
Noncontrolling Interest [Line Items]
Stockholders' Equity Attributable to Noncontrolling Interest, Beginning of Period		29,803	28,074	29,784	27,731
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders		(1,200)	(2,226)	(4,519)	(6,820)
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest		1,962	1,646	5,300	6,583
Stockholders' Equity Attributable to Noncontrolling Interest, End of Period		$ 30,565	$ 27,494	$ 30,565	$ 27,494

Noncontrolling Interests Noncon

Noncontrolling Interests Noncontrolling Interest Rollforward, By Affiliate (Details) - USD ($) $ in Thousands	May 10, 2019	Jul. 02, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount, Beginning of Period				$ 676,950	$ 692,376	$ 732,295
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest			$ 14,266	8,852	36,595	24,460
Noncontrolling Interest, Increase from Business Combination					11,715
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests					(8,789)	(15,547)
Noncontrolling Interest, Change in Redemption Value					17,079	14,962
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					(22,775)	(25,538)
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange					(833)	(5,009)
Redeemable Noncontrolling Interest, Equity, Carrying Amount, End of Period			668,353		668,353
Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount, Beginning of Period				539,972	540,595	573,950
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest					27,589	23,424
Noncontrolling Interest, Increase from Business Combination					11,715
Noncontrolling Interest, Change in Redemption Value					3,095	1,037
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					(22,775)	(25,538)
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange					(833)	(5,009)
Redeemable Noncontrolling Interest, Equity, Carrying Amount, End of Period			524,889	539,972	524,889	539,972
Other Affiliates [Member] \| Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount, Beginning of Period					1,228	1,509
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest					(115)	(205)
Noncontrolling Interest, Increase from Business Combination					11,715
Noncontrolling Interest, Change in Redemption Value						0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					3	11
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange					(43)	0
Redeemable Noncontrolling Interest, Equity, Carrying Amount, End of Period			12,782	1,293	12,782	1,293
EnTrustPermal [Member] \| Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount, Beginning of Period					380,684	386,884
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest					12,694	9,752
Noncontrolling Interest, Change in Redemption Value					0	0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					(9,892)	(13,475)
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange					0	0
Redeemable Noncontrolling Interest, Equity, Carrying Amount, End of Period			383,486	383,161	383,486	383,161
Clarion Partners [Member] \| Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount, Beginning of Period					123,502	117,272
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest					14,904	12,460
Noncontrolling Interest, Change in Redemption Value					3,095	1,037
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					(12,880)	(10,359)
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange					0	0
Redeemable Noncontrolling Interest, Equity, Carrying Amount, End of Period			128,621	120,410	128,621	120,410
RARE Infrastructure, Ltd [Member]
Noncontrolling Interest [Line Items]
Total Consideration for Repurchase of Redeemable Noncontrolling Interest					21,988
Payments for Repurchase of Redeemable Noncontrolling Interest	$ 11,967
RARE Infrastructure, Ltd [Member] \| Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount, Beginning of Period					35,181	68,285
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest					106	1,417
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests					(8,789)	(15,547)
Noncontrolling Interest, Change in Redemption Value		$ 12,345	(25,708)		(25,708)	(12,345)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					0	(1,693)
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange					(790)	(5,009)
Redeemable Noncontrolling Interest, Equity, Carrying Amount, End of Period			$ 0	$ 35,108	$ 0	$ 35,108
EnTrustPermal [Member]
Noncontrolling Interest [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners			35.00%		35.00%
Clarion Partners [Member]
Noncontrolling Interest [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners			18.00%		18.00%

Noncontrolling Interests RARE N

Noncontrolling Interests RARE Noncontrolling Interest Purchase (Details) - USD ($) $ in Thousands	May 10, 2019	Jul. 02, 2018	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Fair Value	$ 34,497	$ 27,892
Noncontrolling Interest, Change in Redemption Value				$ (17,079)	$ (14,962)
Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Noncontrolling Interest, Change in Redemption Value				(3,095)	(1,037)
RARE Infrastructure, Ltd [Member]
Noncontrolling Interest [Line Items]
Payments for Repurchase of Redeemable Noncontrolling Interest	$ 11,967
Payments of Ordinary Dividends, Noncontrolling Interest		981	$ 1,759
Deferred Compensation Arrangement with Individual, Compensation Expense				11,440
Redeemable Noncontrolling Interest, Equity, Fair Value		15,547
RARE Infrastructure, Ltd [Member] \| Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Noncontrolling Interest, Change in Redemption Value		$ (12,345)	$ 25,708	$ 25,708	$ 12,345

Derivatives and Hedging Derivat

Derivatives and Hedging Derivative Instruments and Hedging Activities Disclosure (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	Mar. 31, 2019
Other Assets [Member]
Derivative
Amount Net for Fair Value of Derivative Assets and (Liabilities)	$ 3,074	$ 4,183
Other Liabilities [Member]
Derivative
Amount Net for Fair Value of Derivative Assets and (Liabilities)	$ 1,362	$ 7,579
Foreign Exchange Forward [Member]
Derivative
Derivative, Average Remaining Maturity	7 months
Derivative, Notional Amount	$ 323,654
Future [Member]
Derivative
Derivative, Average Remaining Maturity	3 months
Derivative, Notional Amount	$ 95,910
Total Return Swap [Member]
Derivative
Derivative, Average Remaining Maturity	5 months
Derivative, Notional Amount	$ 34,907
Derivative, Average Basis Spread on Variable Rate	1.60%
Futures Related to Total Return Swap [Member]
Derivative
Derivative, Average Remaining Maturity	3 months
Derivative Financial Instruments, Assets [Member] \| Future [Member]
Derivative
Derivative, Notional Amount	$ 7,916

Derivatives and Hedging Fair Va

Derivatives and Hedging Fair Value of Derivative Assets (Details 1) - Not Designated as Hedging Instrument [Member] - Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Derivative
Derivative Asset, Fair Value, Gross Asset	$ 4,092	$ 3,997
Derivative Asset, Fair Value, Gross Liability	(1,310)	(1,874)
Derivative Asset	2,782	2,123
Derivative Asset, Not Subject to Master Netting Arrangement	292	2,060
Derivative Asset, Collateral, Obligation to Return Cash, Offset	961	2,310
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	4,035	6,493
Foreign Exchange Forward [Member]
Derivative
Derivative Asset, Fair Value, Gross Asset	4,092	3,997
Derivative Asset, Fair Value, Gross Liability	(1,310)	(1,874)
Derivative Asset	2,782	2,123
Derivative Asset, Not Subject to Master Netting Arrangement	0
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	2,782	2,123
Total Return Swap [Member]
Derivative
Derivative Asset, Fair Value, Gross Asset		0
Derivative Asset, Fair Value, Gross Liability		0
Derivative Asset		0
Derivative Asset, Not Subject to Master Netting Arrangement	292	2,060
Derivative Asset, Collateral, Obligation to Return Cash, Offset	961	2,310
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	$ 1,253	$ 4,370

Derivatives and Hedging Fair _2

Derivatives and Hedging Fair Value of Derivative Liabilities (Details) - Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member] - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Derivative
Derivative Liability, Fair Value, Gross Liability	$ (1,426)	$ (7,465)
Derivative Liability, Fair Value, Gross Asset	986	2,094
Derivative Liability	(440)	(5,371)
Derivative Liability, Not Subject to Master Netting Arrangement	(922)	(2,208)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	6,065	8,744
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	4,703	1,165
Derivative Asset, Not Subject to Master Netting Arrangement	292	2,060
Derivative Asset, Collateral, Obligation to Return Cash, Offset	961	2,310
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	4,035	6,493
Foreign Exchange Forward [Member]
Derivative
Derivative Liability, Fair Value, Gross Liability	(1,426)	(7,465)
Derivative Liability, Fair Value, Gross Asset	986	2,094
Derivative Liability	(440)	(5,371)
Derivative Liability, Not Subject to Master Netting Arrangement	0	0
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		0
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	(440)	(5,371)
Derivative Asset, Not Subject to Master Netting Arrangement	0
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	2,782	2,123
Future [Member]
Derivative
Derivative Liability, Fair Value, Gross Liability		0
Derivative Liability, Fair Value, Gross Asset		0
Derivative Liability		0
Derivative Liability, Not Subject to Master Netting Arrangement	(850)	(2,208)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	5,175	8,744
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	4,325	6,536
Futures Related to Total Return Swap [Member]
Derivative
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative Liability, Fair Value, Gross Asset	0	0
Derivative Liability	0	0
Derivative Liability, Not Subject to Master Netting Arrangement	(49)	(410)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	366	1,104
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	317	694
Derivative Asset, Not Subject to Master Netting Arrangement	(72)
Derivative Asset, Collateral, Obligation to Return Cash, Offset	890
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	818
Investments [Domain] \| Future [Member]
Derivative
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative Liability, Fair Value, Gross Asset	0	0
Derivative Liability	0	0
Derivative Liability, Not Subject to Master Netting Arrangement	(801)	(1,798)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	4,809	7,640
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	$ 4,008	$ 5,842

Derivatives and Hedging Gains a

Derivatives and Hedging Gains and (Losses) of Derivative Instruments (Details) - Not Designated as Hedging Instrument [Member] - Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain	$ 11,391	$ 24,457	$ 12,536	$ 39,410
Derivative Instruments Not Designated as Hedging Instruments, Loss	(14,499)	(8,003)	(22,154)	(31,576)
Forward Contracts [Member] \| Other Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain	10,325	3,110	7,813	9,369
Derivative Instruments Not Designated as Hedging Instruments, Loss	(4,293)	(5,587)	(8,257)	(19,366)
Futures Related to Total Return Swap [Member] \| Other Nonoperating Income (Expense) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain	31	3,121	84	3,425
Derivative Instruments Not Designated as Hedging Instruments, Loss	(563)	(467)	(1,441)	(3,418)
Total Return Swap [Member] \| Other Nonoperating Income (Expense) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain	384	203	1,885	1,869
Derivative Instruments Not Designated as Hedging Instruments, Loss	(73)	(832)	0	(938)
Proprietary Funds [Member] \| Forward Contracts [Member] \| Other Nonoperating Income (Expense) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain	651	1,503	2,356	5,523
Derivative Instruments Not Designated as Hedging Instruments, Loss	(2,219)	(1,116)	(1,233)	(788)
Investments [Member] \| Future [Member] \| Other Nonoperating Income (Expense) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain	0	16,520	398	19,224
Derivative Instruments Not Designated as Hedging Instruments, Loss	$ (7,351)	$ (1)	$ (11,223)	$ (7,066)

Strategic Business Initiative_3

Strategic Business Initiative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended	12 Months Ended
	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	$ 18,474		$ 67,297	$ 76,649
Restructuring Reserve, Beginning of Period		$ 0	8,594	0
Restructuring Charges		8,594	53,346
Payments for Restructuring			(18,167)
Restructuring Reserve, End of Period	43,773	8,594	43,773	43,773
Restructuring Reserve, Settled without Cash		758	13,951	14,709
Compensation and benefits
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	53,308		53,308	53,308
Restructuring Reserve, Beginning of Period		0	0	0
Restructuring Charges		0	40,860
Payments for Restructuring			(7,992)
Restructuring Reserve, End of Period	32,868	0	32,868	32,868
Restructuring Reserve, Settled without Cash		0	12,448	12,448
Occupancy
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	8,778		8,778	8,778
Restructuring Reserve, Beginning of Period		0	2,090	0
Restructuring Charges		2,090	4,427
Payments for Restructuring			(289)
Restructuring Reserve, End of Period	6,228	2,090	6,228	6,228
Restructuring Reserve, Settled without Cash		758	1,503	2,261
Other
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	14,563		14,563	14,563
Restructuring Reserve, Beginning of Period		0	6,504	0
Restructuring Charges		6,504	8,059
Payments for Restructuring			(9,886)
Restructuring Reserve, End of Period	4,677	6,504	4,677	4,677
Restructuring Reserve, Settled without Cash		$ 0	0	0
Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	125,000		125,000	125,000
Restructuring and Related Cost, Expected Cost Remaining	48,000		48,000	48,000
Minimum [Member] \| Compensation and benefits
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost Remaining	12,000		12,000	12,000
Minimum [Member] \| Occupancy
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost Remaining	16,000		16,000	16,000
Minimum [Member] \| Other
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost Remaining	20,000		20,000	20,000
Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	135,000		135,000	135,000
Restructuring and Related Cost, Expected Cost Remaining	58,000		58,000	58,000
Maximum [Member] \| Compensation and benefits
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost Remaining	17,000		17,000	17,000
Maximum [Member] \| Occupancy
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost Remaining	18,000		18,000	18,000
Maximum [Member] \| Other
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost Remaining	$ 23,000		$ 23,000	$ 23,000

Variable Interest Entities an_3

Variable Interest Entities and Consolidation of Investment Vehicles Information about Investments in CIV's (Details)	Dec. 31, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Variable Interest Entity
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 38,416,000	$ 43,712,000	$ 71,564,000
Sponsored Investment Fund [Member]
Variable Interest Entity
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	9,419,000	11,671,000	12,863,000
Foreign Mutual Funds [Member]
Variable Interest Entity
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	21,669,000	23,005,000	49,251,000
Employee Owned Funds [Member]
Variable Interest Entity
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	4,564,000	6,215,000	6,963,000
Sponsored ETF [Member]
Variable Interest Entity
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 2,764,000	$ 2,821,000	$ 2,487,000
Consolidated Investment Vehicles [Member]
Variable Interest Entity
Number of Funds	11	14	14
Consolidated Investment Vehicles [Member] \| Sponsored Investment Fund [Member]
Variable Interest Entity
Number of Funds	2	2	2
Consolidated Investment Vehicles [Member] \| Foreign Mutual Funds [Member]
Variable Interest Entity
Number of Funds	6	7	8
Consolidated Investment Vehicles [Member] \| Employee Owned Funds [Member]
Variable Interest Entity
Number of Funds	1	2	2
Consolidated Investment Vehicles [Member] \| Sponsored ETF [Member]
Variable Interest Entity
Number of Funds	2	3	2
Future [Member]
Variable Interest Entity
Derivative, Notional Amount	$ 34,907,000
Voting Right Entities [Member]
Variable Interest Entity
Number of Funds	4	5	7
Investments	$ 39,130	$ 24,924	$ 29,355

VIE Consolidated Balance Sheet

VIE Consolidated Balance Sheet Detail (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018
Variable Interest Entity
REDEEMABLE NONCONTROLLING INTERESTS	$ 668,353	$ 692,376		$ 676,950	$ 732,295
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity
Current Assets	(117,167)	(144,091)
Non-current Assets	3,942	8,993
TOTAL ASSETS	121,109	153,084
Current Liabilities	1,364	5,742
Non-current Liabilities	0	0
TOTAL LIABILITIES	1,364	5,742
REDEEMABLE NONCONTROLLING INTERESTS	0	0
Total Stockholders' Equity	119,745	147,342
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	121,109	153,084
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Variable Interest Entity
Current Assets	(1,896,010)	(1,916,485)
Non-current Assets	6,061,015	5,768,265
TOTAL ASSETS	7,957,025	7,684,750
Current Liabilities	929,495	1,104,002
Non-current Liabilities	2,605,229	2,302,463
TOTAL LIABILITIES	3,534,724	3,406,465
REDEEMABLE NONCONTROLLING INTERESTS	587,024	588,746
Total Stockholders' Equity	3,835,277	3,689,539
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	7,957,025	7,684,750
Consolidated Legg Mason, Inc.
Variable Interest Entity
Current Assets	(1,975,932)	(2,019,856)
Non-current Assets	6,063,786	5,774,266
TOTAL ASSETS	8,039,718	7,794,122
Current Liabilities	930,859	1,109,744
Non-current Liabilities	2,605,229	2,302,463
TOTAL LIABILITIES	3,536,088	3,412,207
REDEEMABLE NONCONTROLLING INTERESTS	668,353	692,376
Total Stockholders' Equity	3,835,277	3,689,539	$ 3,652,683
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	8,039,718	7,794,122
Consolidation, Eliminations [Member]
Variable Interest Entity
Current Assets	37,245	40,720
Non-current Assets	(1,171)	(2,992)
TOTAL ASSETS	(38,416)	(43,712)
Current Liabilities	0	0
Non-current Liabilities	0	0
TOTAL LIABILITIES	0	0
REDEEMABLE NONCONTROLLING INTERESTS	81,329	103,630
Total Stockholders' Equity	(119,745)	(147,342)
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ (38,416)	$ (43,712)

VIE Consolidated Income Stateme

VIE Consolidated Income Statements Details (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Condensed Income Statements, Captions [Line Items]
Total Operating Revenues	$ 753,914	$ 704,322	$ 2,202,538	$ 2,210,654
Net Income (Loss) Attributable to Noncontrolling Interest	16,228	10,498	41,895	31,043
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Condensed Income Statements, Captions [Line Items]
Total Operating Revenues	753,983	704,477	2,202,888	2,211,115
Total Operating Expenses	623,817	940,561	1,862,253	2,184,807
OPERATING INCOME	130,166	(236,084)	340,635	26,308
Total Other Non-Operating Income (Expense)	(7,300)	(32,158)	(40,072)	(74,131)
INCOME BEFORE INCOME TAX PROVISION	122,866	(268,242)	300,563	(47,823)
Income tax provision	33,664	(60,354)	80,466	165
NET INCOME	89,202	(207,888)	220,097	(47,988)
Net Income (Loss) Attributable to Noncontrolling Interest	14,427	9,000	32,889	30,007
Net Income Attributable to Legg Mason, Inc.	74,775	(216,888)	187,208	(77,995)
Variable Interest Entity, Primary Beneficiary [Member]
Condensed Income Statements, Captions [Line Items]
Total Operating Revenues	0	0	0	0
Total Operating Expenses	166	308	1,292	1,386
OPERATING INCOME	(166)	(308)	(1,292)	(1,386)
Total Other Non-Operating Income (Expense)	569	2,612	15,625	2,070
INCOME BEFORE INCOME TAX PROVISION	403	2,304	14,333	684
Income tax provision	0	0	0	0
NET INCOME	403	2,304	14,333	684
Net Income (Loss) Attributable to Noncontrolling Interest	(245)	242	721	115
Net Income Attributable to Legg Mason, Inc.	648	2,062	13,612	569
Consolidated Legg Mason, Inc.
Condensed Income Statements, Captions [Line Items]
Total Operating Revenues	753,914	704,322	2,202,538	2,210,654
Total Operating Expenses	623,920	940,749	1,863,632	2,185,677
OPERATING INCOME	129,994	(236,427)	338,906	24,977
Total Other Non-Operating Income (Expense)	(5,327)	(30,317)	(29,337)	(71,764)
INCOME BEFORE INCOME TAX PROVISION	124,667	(266,744)	309,569	(46,787)
Income tax provision	33,664	(60,354)	80,466	165
NET INCOME	91,003	(206,390)	229,103	(46,952)
Net Income (Loss) Attributable to Noncontrolling Interest	16,228	10,498	41,895	31,043
Net Income Attributable to Legg Mason, Inc.	74,775	(216,888)	187,208	(77,995)
Consolidation, Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Total Operating Revenues	(69)	(155)	(350)	(461)
Total Operating Expenses	(63)	(120)	87	(516)
OPERATING INCOME	(6)	(35)	(437)	55
Total Other Non-Operating Income (Expense)	1,404	(771)	(4,890)	297
INCOME BEFORE INCOME TAX PROVISION	1,398	(806)	(5,327)	352
Income tax provision	0	0	0	0
NET INCOME	1,398	(806)	(5,327)	352
Net Income (Loss) Attributable to Noncontrolling Interest	2,046	1,256	8,285	921
Net Income Attributable to Legg Mason, Inc.	$ (648)	$ (2,062)	$ (13,612)	$ (569)

Fair Value of Assets and Liabil

Fair Value of Assets and Liabilities of CIVs by Level (Details 3) - Consolidated Investment Vehicles [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 78,957	$ 70,197
Fair Value Measured at Net Asset Value Per Share [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	3,619	12,547
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 25,536	55,182
Other Liabilities, Fair Value Disclosure		$ 4,217

CIV's with Fair Value Determine

CIV's with Fair Value Determined using NAV (Details 6) - CIVs - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Hedge Funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of Monthly Redemption	22.00%
Percentage of Quarterly Redemption	77.00%
Percentage Subject to Lock in Period	1.00%
Fair Value Measured at Net Asset Value Per Share [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Assets, Fair Value Disclosure	$ 3,619	$ 12,547
Fair Value Measured at Net Asset Value Per Share [Member] \| Hedge Funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Assets, Fair Value Disclosure		$ 12,547

Unconsolidated VIE's (Details 9

Unconsolidated VIE's (Details 9) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Variable Interest Entity
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 38,416	$ 43,712	$ 71,564
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	43,402	35,967
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	63,698	61,138
Assets Under Management	29,677,965	29,025,764
Real Estate Investment Trusts [Member]
Variable Interest Entity
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	12,312	10,812
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	14,052	15,241
Other sponsored investments fund [Member]
Variable Interest Entity
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	31,090	25,155
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 49,646	$ 45,897