Janus Henderson (JHG) 10-Q2 Aug 232023 Q2 Quarterly reportFinancial data

Company Profile

Document And Entity Information

Document And Entity Information - shares	6 Months Ended
Document And Entity Information - shares	Jun. 30, 2023	Jul. 31, 2023
Document Information [Line Items]
Entity Central Index Key	0001274173
Entity Registrant Name	JANUS HENDERSON GROUP PLC
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q2
Document Fiscal Year Focus	2023
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2023
Document Transition Report	false
Entity File Number	001-38103
Entity Incorporation, State or Country Code	Y9
Entity Tax Identification Number	98-1376360
Entity Address, Address Line One	201 Bishopsgate
Entity Address, City or Town	London
Entity Address, Country	GB
Entity Address, Postal Zip Code	EC2M3AE
City Area Code	0
Local Phone Number	20 7818 1818
Title of 12(b) Security	Common Stock, $1.50 Per Share Par Value
Trading Symbol	JHG
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		165,657,905

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 996.9	$ 1,162.3
Investments	312	261.6
Fees and other receivables	246.9	252.9
OEIC and unit trust receivables	105	65.7
Other current assets	132.2	120.3
Total current assets	2,292.7	2,214.8
Non-current assets:
Property, equipment and software, net	48.3	51.8
Intangible assets, net	2,430.3	2,414.7
Goodwill	1,287.3	1,253.1
Retirement benefit asset, net	104.4	97.9
Other non-current assets	225.2	205.5
Total assets	6,388.2	6,237.8
Current liabilities:
Accounts payable and accrued liabilities	212.5	232.6
Current portion of accrued compensation, benefits and staff costs	176.8	300.8
OEIC and unit trust payables	112.4	72.8
Total current liabilities	506.7	610.5
Non-current liabilities:
Accrued compensation, benefits and staff costs	29.9	46.9
Long-term debt	306	307.5
Deferred tax liabilities, net	578.9	574.6
Retirement benefit obligations, net	3	3
Other non-current liabilities	92.1	98.8
Total liabilities	1,516.6	1,641.3
Commitments and contingencies (See Note 15)
REDEEMABLE NONCONTROLLING INTERESTS	389.8	233.9
EQUITY
Common stock, $1.50 par value; 480,000,000 shares authorized, and 165,657,905 and 165,657,905 shares issued and outstanding as of June 30, 2023, and December 31, 2022, respectively	248.5	248.5
Additional paid-in capital	3,687.1	3,706.6
Treasury shares, 43,564 and 312,469 shares held at June 30, 2023, and December 31, 2022, respectively	(1.1)	(8.3)
Accumulated other comprehensive loss, net of tax	(564.1)	(647.7)
Retained earnings	1,108.6	1,060.7
Total shareholders’ equity	4,479	4,359.8
Nonredeemable noncontrolling interests	2.8	2.8
Total equity	4,481.8	4,362.6
Total liabilities, redeemable noncontrolling interests and equity	6,388.2	6,237.8
Variable Interest Entity, Primary Beneficiary [Member]
Current assets:
Cash and cash equivalents	27.5	14.1
Investments	464.1	334.3
Other current assets	8.1	3.6
Current liabilities:
Accounts payable and accrued liabilities	$ 5	$ 4.3

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parentheticals) - $ / shares	Jun. 30, 2023	Dec. 31, 2022
Common stock, par value (in dollars per share)	$ 1.50	$ 1.50
Common stock, shares authorized (in shares)	480,000,000	480,000,000
Common stock, shares issued (in shares)	165,657,905	165,657,905
Common stock, shares outstanding (in shares)	165,657,905	165,657,905
Treasury shares (in shares)	43,564	312,469

Condensed Consolidated Statemen

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Total revenue	$ 516.5	$ 555.5	$ 1,012.3	$ 1,175.5
Operating expenses:
Employee compensation and benefits	147.7	145	288	309.6
Long-term incentive plans	37.6	40.7	93.1	92.1
Distribution expenses	114.6	127.8	226.6	269.6
Investment administration	11.1	10.3	22.7	25.1
Marketing	9.3	7.8	18.1	15.2
General, administrative and occupancy	72.2	72.3	133.3	145.4
Depreciation and amortization	6.1	7.7	12.2	17.2
Total operating expenses	398.6	411.6	794	874.2
Operating income:	117.9	143.9	218.3	301.3
Interest expense	(3.2)	(3.2)	(6.3)	(6.4)
Investment gains (losses), net	6.9	(109.4)	24.5	(141.6)
Other non-operating income (expenses), net	7	0.6	14.1	(7.2)
Income before taxes	128.6	31.9	250.6	146.1
Income tax benefit (provision)	(28.2)	(36.7)	(54.2)	(67.4)
Net income (loss)	100.4	(4.8)	196.4	78.7
Net loss (income) attributable to noncontrolling interests	(10.6)	101	(19.2)	121.1
Net income attributable to JHG	$ 89.8	$ 96.2	$ 177.2	$ 199.8
Earnings (loss) per share attributable to JHG common shareholders:
Basic (in dollars per share)	$ 0.54	$ 0.58	$ 1.07	$ 1.19
Diluted (in dollars per share)	$ 0.54	$ 0.57	$ 1.07	$ 1.19
Other comprehensive income (loss), net of tax:
Foreign currency translation gains (losses)	$ 40.5	$ (177.8)	$ 85	$ (224.8)
Actuarial gains	0.1	0.1	0.2	0.2
Other comprehensive income (loss), net of tax	40.6	(177.7)	85.2	(224.6)
Other comprehensive loss (income) attributable to noncontrolling interests	1.6	23.6	(1.6)	23.4
Other comprehensive income (loss) attributable to JHG	42.2	(154.1)	83.6	(201.2)
Total comprehensive income (loss)	141	(182.5)	281.6	(145.9)
Total comprehensive loss (income) attributable to noncontrolling interests	(9)	124.6	(20.8)	144.5
Total comprehensive income (loss) attributable to JHG	132	(57.9)	260.8	(1.4)
Investment Advice [Member]
Total revenue	423.5	453.6	838.1	967.6
Investment Performance [Member]
Total revenue	(5.9)	(3.4)	(20.8)	(11.8)
Shareholder Service [Member]
Total revenue	53.3	56.3	104.8	118.7
Product and Service, Other [Member]
Total revenue	$ 45.6	$ 49	$ 90.2	$ 101

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Operating activities:
Net income	$ 196.4	$ 78.7
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	12.2	17.2
Deferred income taxes	1	8.3
Stock-based compensation plan expense	42.9	45.8
Loss on sale of Intech	0	9.1
Investment losses (gains), net	(24.5)	141.6
Contributions to pension plans in excess of costs recognized	(0.9)	0.2
Other, net	(2.5)	9.6
Changes in operating assets and liabilities:
OEIC and unit trust receivables and payables	0.3	(1.1)
Other assets	15	25.5
Other accruals and liabilities	(176.7)	(229.5)
Net operating activities	63.2	105.4
Investing activities:
Investments, net	(79.2)	3.7
Property, equipment and software	(6.5)	(7.5)
Investments by consolidated seeded investment products, net	(163)	24.6
Cash received (paid) on settled seed capital hedges, net	(9.3)	44.9
Dividends received from equity method investments	0.7	0.5
Long-term note with Intech	(1)	(12)
Proceeds from sale of Intech	0	5
Receipt of contingent consideration payments from sale of subsidiaries	0.2	0
Net investing activities	(258.1)	59.2
Financing activities:
Proceeds from stock-based compensation plans	2.3	2.2
Purchase of common stock for stock-based compensation plans	(57.5)	(97)
Purchase of common stock for share buyback program	0	(98.9)
Dividends paid to shareholders	(129.3)	(129.8)
Revolving credit facility issuance costs	(1)	0
Distributions to noncontrolling interests	0	(1)
Third-party sales (purchases) in consolidated seeded investment products, net	201.6	(25.4)
Principal payments under capital lease obligations	(0.4)	(0.8)
Net financing activities	15.7	(350.7)
Cash and cash equivalents:
Effect of foreign exchange rate changes	27.2	(58.8)
Net change	(152)	(244.9)
At beginning of period	1,176.4	1,118.6
At end of period	1,024.4	873.7
Supplemental cash flow information:
Cash paid for interest	7.3	7.3
Cash paid for income taxes, net of refunds	56	92.8
Reconciliation of cash and cash equivalents:
Total cash and cash equivalents	1,024.4	873.7
Consolidated Entity, Excluding VIE [Member]
Reconciliation of cash and cash equivalents:
Total cash and cash equivalents	996.9	863.1
Variable Interest Entity, Primary Beneficiary [Member]
Reconciliation of cash and cash equivalents:
Total cash and cash equivalents	$ 27.5	$ 10.6

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Changes In Equity (Unaudited) - USD ($) $ in Thousands, shares in Millions	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock, Common [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Noncontrolling Interest [Member]	Total
Balance (in shares) at Dec. 31, 2021	169
Balance at Dec. 31, 2021	$ 253,600	$ 3,771,800	$ (55,100)	$ (387,000)	$ 1,040,200	$ 15,400	$ 4,638,900
Net income	0	0	0	0	199,800	0	199,800
Other comprehensive income (loss)	0	0	0	(201,200)	0	0	(201,200)
Dividends paid to shareholders	0		0	0	(129,800)	0	(129,800)
Dividends paid to shareholders	0		0	0	(129,800)	0	(129,800)
Purchase of common stock for stock-based compensation plans	0	(96,400)	(600)	0	0	0	(97,000)
Vesting of stock-based compensation plans	0	(49,800)	49,800	0	0	0	0
Stock-based compensation plan expense	0	45,800	0	0	0	0	45,800
Proceeds from stock-based compensation plans	$ 0	2,200	0	0	0	0	2,200
Purchase of common stock from share buyback program (in shares)	(3.3)
Purchase of common stock from share buyback program	$ (5,100)	0	0	0	(93,800)	0	(98,900)
Dividends paid to shareholders		0
Distributions to noncontrolling interests	0	0	0	0	0	(1,000)	(1,000)
Sale of Intech	0	0	0	0	0	(11,600)	(11,600)
Fair value adjustments to redeemable noncontrolling interests	$ 0	0	0	0	1,400	0	1,400
Balance (in shares) at Jun. 30, 2022	165.7
Balance at Jun. 30, 2022	$ 248,500	3,673,600	(5,900)	(588,200)	1,017,800	2,800	4,348,600
Balance (in shares) at Mar. 31, 2022	167.8
Balance at Mar. 31, 2022	$ 251,700	3,684,900	(40,300)	(434,100)	1,039,500	2,800	4,504,500
Net income	0	0	0	0	96,200	0	96,200
Other comprehensive income (loss)	0	0	0	(154,100)	0	0	(154,100)
Dividends paid to shareholders	0	0	0	0	(65,500)	0	(65,500)
Dividends paid to shareholders	0	0	0	0	(65,500)	0	(65,500)
Purchase of common stock for stock-based compensation plans	0	(2,300)	(200)	0	0	0	(2,500)
Vesting of stock-based compensation plans	0	(34,600)	34,600	0	0	0	0
Stock-based compensation plan expense	0	23,900	0	0	0	0	23,900
Proceeds from stock-based compensation plans	$ 0	1,700	0	0	0	0	1,700
Purchase of common stock from share buyback program (in shares)	(2.1)
Purchase of common stock from share buyback program	$ (3,200)	0	0	0	(52,400)	0	(55,600)
Balance (in shares) at Jun. 30, 2022	165.7
Balance at Jun. 30, 2022	$ 248,500	3,673,600	(5,900)	(588,200)	1,017,800	2,800	4,348,600
Balance (in shares) at Dec. 31, 2022	165.7
Balance at Dec. 31, 2022	$ 248,500	3,706,600	(8,300)	(647,700)	1,060,700	2,800	4,362,600
Net income	0	0	0	0	177,200	0	177,200
Other comprehensive income (loss)	0	0	0	83,600	0	0	83,600
Dividends paid to shareholders	0		0	0	(129,300)	0	(129,300)
Dividends paid to shareholders	0		0	0	(129,300)	0	(129,300)
Purchase of common stock for stock-based compensation plans	0	(57,000)	(500)	0	0	0	(57,500)
Vesting of stock-based compensation plans	0	(7,700)	7,700	0	0	0	0
Stock-based compensation plan expense	0	42,900	0	0	0	0	42,900
Proceeds from stock-based compensation plans	$ 0	2,300	0	0	0	0	2,300
Dividends paid to shareholders		0
Balance (in shares) at Jun. 30, 2023	165.7
Balance at Jun. 30, 2023	$ 248,500	3,687,100	(1,100)	(564,100)	1,108,600	2,800	4,481,800
Balance (in shares) at Mar. 31, 2023	165.7
Balance at Mar. 31, 2023	$ 248,500	3,663,400	(1,100)	(606,300)	1,083,400	2,800	4,390,700
Net income	0	0	0	0	89,800	0	89,800
Other comprehensive income (loss)	0	0	0	42,200	0	0	42,200
Dividends paid to shareholders	0	0	0	0	(64,600)	0	(64,600)
Dividends paid to shareholders	0	0	0	0	(64,600)	0	(64,600)
Purchase of common stock for stock-based compensation plans	0		(300)	0	0	0	0
Purchase of common stock for stock-based compensation plans		300
Vesting of stock-based compensation plans	0	(200)	300	0	0	0	100
Stock-based compensation plan expense	0	21,300	0	0	0	0	21,300
Proceeds from stock-based compensation plans	$ 0	2,300	0	0	0	0	2,300
Balance (in shares) at Jun. 30, 2023	165.7
Balance at Jun. 30, 2023	$ 248,500	$ 3,687,100	$ (1,100)	$ (564,100)	$ 1,108,600	$ 2,800	$ 4,481,800

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Changes In Equity (Unaudited) (Parentheticals) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Dividends paid (in dollars per share)	$ 0.39	$ 0.39	$ 0.78	$ 0.77

Note 1 - Basis of Presentation

Note 1 - Basis of Presentation	6 Months Ended
Note 1 - Basis of Presentation	Jun. 30, 2023
Notes to Financial Statements
Basis of Presentation and Significant Accounting Policies [Text Block]	Note 1 Basis of Presentation Basis of Presentation In the opinion of management of Janus Henderson Group plc (“JHG,” “the Company,” “we,” “us,” “our” and similar terms), the accompanying unaudited condensed consolidated financial statements contain all normal recurring adjustments necessary to fairly state our financial position, results of operations and cash flows in accordance with accounting principles generally accepted in the United States of America (“GAAP”). Such financial statements have been prepared in accordance with the instructions to Form 10 not 10 December 31, 2022 Revision of Previously Issued Financial Statements In conjunction with the preparation of our third 2022 2021 2020 2022 not 2022 2022 In the first 2020, first 2020, not first 2022 third 2022 The following tables present line items for the financial statements for the three six June 30, 2022, three March 31, 2022, June 30, 2022, not The impact of the error on the Condensed Consolidated Statements of Comprehensive Income for the three June 30, 2022, Three months ended June 30, 2022 As previously reported Impact of revisions As revised Other non-operating income (expenses), net $ (1.7 ) $ 2.3 $ 0.6 Income (loss) before taxes 29.6 2.3 31.9 Net income (loss) (7.1 ) 2.3 (4.8 ) Net income (loss) attributable to JHG $ 93.9 $ 2.3 $ 96.2 Earnings (loss) per share attributable to JHG common shareholders: Basic $ 0.56 $ 0.02 $ 0.58 Diluted $ 0.56 $ 0.01 $ 0.57 Other comprehensive income (loss), net of tax: Foreign currency translation gains (losses) (175.5 ) (2.3 ) (177.8 ) Other comprehensive income (loss), net of tax (175.4 ) (2.3 ) (177.7 ) Other comprehensive income (loss) attributable to JHG $ (151.8 ) $ (2.3 ) $ (154.1 ) The impact of the error on the Condensed Consolidated Statements of Comprehensive Income for the six June 30, 2022, Six months ended June 30, 2022 As previously reported Impact of revisions As revised Operating expenses: Impairment of goodwill and intangible assets $ 32.8 $ (32.8 ) $ — Total operating expenses 907.0 (32.8 ) 874.2 Operating income (loss) 268.5 32.8 301.3 Other non-operating income (expenses), net (9.5 ) 2.3 (7.2 ) Income (loss) before taxes 111.0 35.1 146.1 Income tax benefit (provision) (59.5 ) (7.9 ) (67.4 ) Net income (loss) 51.5 27.2 78.7 Net income (loss) attributable to JHG $ 172.6 $ 27.2 $ 199.8 Earnings (loss) per share attributable to JHG common shareholders: Basic $ 1.03 $ 0.16 $ 1.19 Diluted $ 1.03 $ 0.16 $ 1.19 Other comprehensive income (loss), net of tax: Foreign currency translation gains (losses) (222.5 ) (2.3 ) (224.8 ) Other comprehensive income (loss), net of tax (222.3 ) (2.3 ) (224.6 ) Other comprehensive income (loss) attributable to JHG $ (198.9 ) $ (2.3 ) $ (201.2 ) Total comprehensive income (loss) $ (170.8 ) $ 24.9 $ (145.9 ) Total comprehensive income (loss) attributable to JHG $ (26.3 ) $ 24.9 $ (1.4 )

Note 2 - Dispositions

Note 2 - Dispositions	6 Months Ended
Note 2 - Dispositions	Jun. 30, 2023
Notes to Financial Statements
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]	Note 2 Dispositions On February 3, 2022, March 31, 2022, seventh The terms of the transaction also included a $20.0 million seven first second June 30, 2023 first second

Note 3 - Consolidation

Note 3 - Consolidation	6 Months Ended
Note 3 - Consolidation	Jun. 30, 2023
Notes to Financial Statements
Variable Interest Entities Voting Rights Entities Consolidation Disclosure [Text Block]	Note 3 Consolidation Variable Interest Entities Consolidated Variable Interest Entities Our consolidated variable interest entities (“VIEs”) as of June 30, 2023 December 31, 2022 not may not, third no Unconsolidated Variable Interest Entities As of June 30, 2023 December 31, 2022 Voting Rights Entities Consolidated Voting Rights Entities The following table presents the balances related to consolidated voting rights entities (“VREs”) that were recorded on our Condensed Consolidated Balance Sheets, including our net interest in these products (in millions): June 30, December 31, 2023 2022 Investments $ 242.2 $ 206.0 Cash and cash equivalents 30.9 5.8 Other current assets 12.1 1.8 Accounts payable and accrued liabilities (1.6 ) (1.0 ) Total $ 283.6 $ 212.6 Redeemable noncontrolling interests in consolidated VREs (89.2 ) (35.1 ) JHG's net interest in consolidated VREs $ 194.4 $ 177.5 Third-party assets held in consolidated VREs are not may not, third no Our total exposure to consolidated VREs represents the value of our economic ownership interest in these seeded investment products. Unconsolidated Voting Rights Entities As of June 30, 2023 December 31, 2022

Note 4 - Investment Securities

Note 4 - Investment Securities	6 Months Ended
Note 4 - Investment Securities	Jun. 30, 2023
Notes to Financial Statements
Investment [Text Block]	Note 4 Investments Our investments as of June 30, 2023 December 31, 2022 June 30, December 31, 2023 2022 Current investments: Seeded investment products: Consolidated VIEs $ 464.1 $ 334.3 Consolidated VREs 242.2 206.0 Unconsolidated VIEs and VREs 8.6 4.9 Separately managed accounts 41.1 29.7 Total seeded investment products 756.0 574.9 Investments related to deferred compensation plans 11.5 10.7 Other investments 8.6 10.3 Total current investments $ 776.1 $ 595.9 Non-current investments: Equity method investments 31.5 18.7 Total investments $ 807.6 $ 614.6 Net unrealized gains (losses) on investments held as of June 30, 2023 2022 three six June 30, 2023 2022 Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Unrealized gains (losses) on investments held at period end $ 6.7 $ (109.4 ) $ 20.5 $ (141.6 ) Investment Gains (Losses), Net Investment gains (losses), net in our Condensed Consolidated Statements of Comprehensive Income included the following for the three six June 30, 2023 2022 Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Seeded investment products and hedges, net $ 9.6 $ (6.7 ) $ 15.0 $ (18.2 ) Third-party ownership interests in seeded investment products 10.6 (101.0 ) 19.2 (121.1 ) Equity method investments (14.5 ) 0.2 (11.5 ) 1.7 Other 1.2 (1.9 ) 1.8 (4.0 ) Investment gains (losses), net $ 6.9 $ (109.4 ) $ 24.5 $ (141.6 ) Investment gains (losses), net for the three six June 30, 2023, Gains and losses attributable to third not Equity Method Investments On June 1, 2023, Cash Flows Cash flows related to our investments for the six June 30, 2023 2022 Six months ended June 30, 2023 2022 Purchases Sales, Purchases Sales, and settlements and Net and settlements and Net settlements maturities cash flow settlements maturities cash flow Investments by consolidated seeded investment products $ (204.8 ) $ 41.8 $ (163.0 ) $ (8.5 ) $ 33.1 $ 24.6 Investments (143.2 ) 64.0 (79.2 ) (40.5 ) 44.2 3.7

Note 5 - Derivative Instruments

Note 5 - Derivative Instruments	6 Months Ended
Note 5 - Derivative Instruments	Jun. 30, 2023
Notes to Financial Statements
Derivative Instruments and Hedging Activities Disclosure [Text Block]	Note 5 Derivative Instruments Derivative Instruments Used to Hedge Seeded Investment Products We maintain an economic hedge program that uses derivative instruments to mitigate against market exposure of certain seeded investments by using index and commodity futures (“futures”), total return swaps and credit default swaps. Certain foreign currency exposures associated with our seeded investment products are also hedged by using foreign currency forward contracts and swaps. We were party to the following derivative instruments as of June 30, 2023 December 31, 2022 Notional value June 30, 2023 December 31, 2022 Futures $ 626.1 $ 196.8 Credit default swaps 125.2 115.1 Total return swaps 39.8 37.2 Foreign currency forward contracts and swaps 189.2 131.7 The derivative instruments are not three six June 30, 2023 2022 Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Futures $ 3.6 $ 21.6 $ (3.1 ) $ 37.0 Credit default swaps (0.6 ) 3.3 (2.5 ) 5.6 Total return swaps (5.7 ) 28.8 (11.7 ) 36.2 Foreign currency forward contracts and swaps 4.3 (2.5 ) 8.8 (9.5 ) Total gains (losses) from derivative instruments $ 1.6 $ 51.2 $ (8.5 ) $ 69.3 Derivative assets and liabilities are generally recognized on a gross basis and included in other current assets or in accounts payable and accrued liabilities in our Condensed Consolidated Balance Sheets. The derivative assets and liabilities as of June 30, 2023 December 31, 2022 Fair value June 30, 2023 December 31, 2022 Derivative assets $ 6.2 $ 5.3 Derivative liabilities 7.2 4.0 In addition to using derivative instruments to mitigate against market exposure of certain seeded investments, we also engage in short sales of securities to hedge seed investments. As of June 30, 2023 December 31, 2022 not Derivative Instruments Used in Consolidated Seeded Investment Products Certain of our consolidated seeded investment products utilize derivative instruments to contribute to the achievement of defined investment objectives. These derivative instruments are classified within other current assets or in accounts payable and accrued liabilities in our Condensed Consolidated Balance Sheets. Gains and losses on these derivative instruments are classified within investment gains (losses), net in our Condensed Consolidated Statements of Comprehensive Income. Our consolidated seeded investment products were party to the following derivative instruments as of June 30, 2023 December 31, 2022 Notional value June 30, 2023 December 31, 2022 Futures $ 822.2 $ 141.3 Credit default swaps 2.1 2.2 Total return swaps — 10.4 Interest rate swaps 2.1 — Options — 0.1 Foreign currency forward contracts and swaps 87.2 18.3 As of June 30, 2023 December 31, 2022 Derivative Instruments Foreign Currency Hedging Program We maintain a foreign currency hedging program to take reasonable measures to minimize the income statement effects of foreign currency remeasurement of monetary balance sheet accounts. The program utilizes foreign currency forward contracts and swaps to achieve its objectives, and it is considered an economic hedge for accounting purposes. The notional value of the foreign currency forward contracts and swaps as of June 30, 2023 December 31, 2022 Notional value June 30, 2023 December 31, 2022 Foreign currency forward contracts and swaps $ 102.4 $ 74.7 The derivative assets and liabilities are generally recognized on a gross basis and included in other current assets or in accounts payable and accrued liabilities in our Condensed Consolidated Balance Sheets. As of June 30, 2023 December 31, 2022 Changes in fair value of the derivatives are recognized in other non-operating income (expenses), net in our Condensed Consolidated Statements of Comprehensive Income. Foreign currency remeasurement is also recognized in other non-operating income (expenses), net in our Condensed Consolidated Statements of Comprehensive Income. For the three six June 30, 2023 2022

Note 6 - Fair Value Measurement

Note 6 - Fair Value Measurements	6 Months Ended
Note 6 - Fair Value Measurements	Jun. 30, 2023
Notes to Financial Statements
Fair Value Disclosures [Text Block]	Note 6 Fair Value Measurements The following table presents assets and liabilities reflected in the financial statements or disclosed in the notes to the financial statements at fair value on a recurring basis as of June 30, 2023 Fair value measurements using: Quoted prices in Significant active markets for other Significant identical assets observable unobservable and liabilities inputs inputs (Level 1) (Level 2) (Level 3) Total Assets: Cash equivalents $ 640.5 $ — $ — $ 640.5 Investments: Consolidated VIEs 285.6 174.1 4.4 464.1 Other investments 274.8 37.1 0.1 312.0 Total investments 560.4 211.2 4.5 776.1 Seed hedge derivatives — 6.2 — 6.2 Derivatives used in consolidated seeded investment products — 1.4 — 1.4 Derivatives used in foreign currency hedging program — 1.2 — 1.2 Intech option agreement — — 0.2 0.2 Intech contingent consideration — — 11.9 11.9 Total assets $ 1,200.9 $ 220.0 $ 16.6 $ 1,437.5 Liabilities: Derivatives used in consolidated seeded investment products $ — $ 0.3 $ — $ 0.3 Derivatives used in foreign currency hedging program — 0.6 — 0.6 Securities sold, not yet purchased 1.5 — — 1.5 Seed hedge derivatives — 7.2 — 7.2 Long-term debt (1) — 294.5 — 294.5 Deferred bonuses — — 78.2 78.2 Total liabilities $ 1.5 $ 302.6 $ 78.2 $ 382.3 ( 1 Carried at amortized cost and disclosed at fair value. The following table presents assets and liabilities reflected in the financial statements or disclosed in the notes to the financial statements at fair value on a recurring basis as of December 31, 2022 Fair value measurements using: Quoted prices in Significant active markets for other Significant identical assets observable unobservable and liabilities inputs inputs (Level 1) (Level 2) (Level 3) Total Assets: Cash equivalents $ 688.4 $ — $ — $ 688.4 Investments: Consolidated VIEs 275.4 54.0 4.9 334.3 Other investments 171.9 89.4 0.3 261.6 Total investments 447.3 143.4 5.2 595.9 Seed hedge derivatives — 5.3 — 5.3 Derivatives used in consolidated seeded investment products — 0.1 — 0.1 Derivatives used in foreign currency hedging program — 0.4 — 0.4 Intech option agreement — — 0.8 0.8 Intech contingent consideration — — 12.1 12.1 Volantis contingent consideration — — 0.2 0.2 Total assets $ 1,135.7 $ 149.2 $ 18.3 $ 1,303.2 Liabilities: Derivatives used in consolidated seeded investment products $ — $ 0.6 $ — $ 0.6 Derivatives used in foreign currency hedging program — 1.1 — 1.1 Securities sold, not yet purchased 0.5 — — 0.5 Seed hedge derivatives — 4.0 — 4.0 Long-term debt (1) — 295.4 — 295.4 Deferred bonuses — — 46.5 46.5 Total liabilities $ 0.5 $ 301.1 $ 46.5 $ 348.1 ( 1 Carried at amortized cost and disclosed at fair value. Level 1 Our Level 1 not Level 2 Our Level 2 2 Level 3 Investments As of June 30, 2023 December 31, 2022 3 Intech Option Agreement and Contingent Consideration As of June 30, 2023 December 31, 2022 Deferred Bonuses Deferred bonuses represent liabilities to employees over the vesting period that will be settled by investments in our products or cash. Upon vesting, employees receive the value of the investment product selected by the participant, adjusted for gains or losses attributable to the product. The significant unobservable inputs used to value the liabilities are investment designations and vesting periods. Changes in Fair Value Changes in fair value of our Level 3 three six June 30, 2023 2022 Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Beginning of period fair value $ 17.8 $ 23.2 $ 18.3 $ 8.8 Intech option agreement — (0.8 ) — 3.1 Contingent consideration from sale of Intech — (0.3 ) — 12.3 Settlement of contingent consideration (0.2 ) — (0.2 ) — Fair value adjustments (0.9 ) (0.3 ) (1.4 ) (1.8 ) Transfers from Level 1 0.2 0.5 0.2 0.5 Transfers to Level 1 — (2.1 ) — (2.1 ) Purchases of securities — 1.2 — 1.0 Sales of securities (0.3 ) — (0.3 ) (0.3 ) Foreign currency translation — (0.3 ) — (0.4 ) End of period fair value $ 16.6 $ 21.1 $ 16.6 $ 21.1 Changes in fair value of our Level 3 three six June 30, 2023 2022 Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Beginning of period fair value $ 60.0 $ 34.3 $ 46.5 $ 50.5 Fair value adjustments 1.1 (1.0 ) 2.6 (2.6 ) Vesting of deferred bonuses (1.1 ) (14.4 ) (34.3) (36.0 ) Amortization of deferred bonuses 17.5 10.8 25.9 19.2 Foreign currency translation 0.7 (2.1 ) 1.7 (3.5 ) Additions — — 35.8 — End of period fair value $ 78.2 $ 27.6 $ 78.2 $ 27.6 Nonrecurring Fair Value Measurements Nonrecurring Level 3 3.

Note 7 - Goodwill and Intangibl

Note 7 - Goodwill and Intangible Assets	6 Months Ended
Note 7 - Goodwill and Intangible Assets	Jun. 30, 2023
Notes to Financial Statements
Goodwill and Intangible Assets Disclosure [Text Block]	Note 7 Goodwill and Intangible Assets The following tables present movements in our intangible assets and goodwill during the six June 30, 2023 2022 Foreign December 31, currency June 30, 2022 Amortization Disposal translation 2023 Indefinite-lived intangible assets: Investment management agreements $ 2,046.5 $ — $ — $ 16.7 $ 2,063.2 Trademarks 360.0 — — — 360.0 Definite-lived intangible assets: Client relationships 68.9 — — 1.6 70.5 Accumulated amortization (60.7 ) (1.0 ) — (1.7 ) (63.4 ) Net intangible assets $ 2,414.7 $ (1.0 ) $ — $ 16.6 $ 2,430.3 Goodwill $ 1,253.1 $ — $ — $ 34.2 $ 1,287.3 Foreign December 31, currency June 30, 2021 Amortization Disposal translation 2022 Indefinite-lived intangible assets: Investment management agreements $ 2,114.8 $ — $ — $ (38.6 ) $ 2,076.2 Trademarks 366.7 — (4.7 ) — 362.0 Definite-lived intangible assets: Client relationships 168.4 — (84.8 ) (6.0 ) 77.6 Accumulated amortization (107.2 ) (2.6 ) 44.7 5.0 (60.1 ) Net intangible assets $ 2,542.7 $ (2.6 ) $ (44.8 ) $ (39.6 ) $ 2,455.7 Goodwill $ 1,341.5 $ — $ (7.0 ) $ (74.8 ) $ 1,259.7 Management Buyout of Intech As detailed in Note 2 March 31, 2022, Future Amortization Expected future amortization expense related to client relationships is summarized below (in millions): Future amortization Amount 2023 (remainder of year) $ 0.7 2024 0.4 2025 0.4 2026 0.4 2027 0.4 Thereafter 4.8 Total $ 7.1

Note 8 - Debt

Note 8 - Debt	6 Months Ended
Note 8 - Debt	Jun. 30, 2023
Notes to Financial Statements
Debt Disclosure [Text Block]	Note 8 Debt Our debt as of June 30, 2023 December 31, 2022 June 30, 2023 December 31, 2022 Carrying Fair Carrying Fair value value value value 4.875% Senior Notes due 2025 $ 306.0 $ 294.5 $ 307.5 $ 295.4 4.875% 2025 The 4.875% Senior Notes due 2025 “2025 February 1 August 1 August 1, 2025. 2025 June 30, 2023 2025 Credit Facility On June 30, 2023 June 30, 2028, two one first second may 3.00x June 30, 2023

Note 9 - Income Taxes

Note 9 - Income Taxes	6 Months Ended
Note 9 - Income Taxes	Jun. 30, 2023
Notes to Financial Statements
Income Tax Disclosure [Text Block]	Note 9 Income Taxes Our effective tax rates for the three six June 30, 2023 2022 Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Effective tax rate 22.0 % 115.4 % 21.6 % 46.1 % The effective tax rate for the three June 30, 2023 six June 30, 2023 2022, As of June 30, 2023 12

Note 10 - Noncontrolling Intres

Note 10 - Noncontrolling Intrests	6 Months Ended
Note 10 - Noncontrolling Intrests	Jun. 30, 2023
Notes to Financial Statements
Noncontrolling Interest Disclosure [Text Block]	Note 10 Noncontrolling Interests Redeemable Noncontrolling Interests Redeemable noncontrolling interests as of June 30, 2023 December 31, 2022 June 30, December 31, 2023 2022 Consolidated seeded investment products $ 389.8 $ 233.9 Consolidated Seeded Investment Products Noncontrolling interests in consolidated seeded investment products are classified as redeemable noncontrolling interests when there is an obligation to repurchase units at the investor’s request. Redeemable noncontrolling interests in consolidated seeded investment products may third The following table presents the movement in redeemable noncontrolling interests in consolidated seeded investment products for the three six June 30, 2023 2022 Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Opening balance $ 384.7 $ 150.7 $ 233.9 $ 148.5 Changes in market value 10.6 (101.0 ) 19.2 (121.1 ) Changes in ownership (4.0 ) 895.0 136.2 917.2 Foreign currency translation (1.5 ) (23.6 ) 0.5 (23.5 ) Closing balance $ 389.8 $ 921.1 $ 389.8 $ 921.1 Nonredeemable Noncontrolling Interests Nonredeemable noncontrolling interests as of June 30, 2023 December 31, 2022 June 30, December 31, 2023 2022 Seed capital investments $ 2.8 $ 2.8

Note 11 - Long-Term Incentive a

Note 11 - Long-Term Incentive and Employee Compensation	6 Months Ended
Note 11 - Long-Term Incentive and Employee Compensation	Jun. 30, 2023
Notes to Financial Statements
Share-Based Payment Arrangement [Text Block]	Note 11 Long-Term Incentive and Employee Compensation The following table presents restricted stock and mutual fund awards granted during the three six June 30, 2023 Three months ended Six months ended June 30, June 30, 2023 2023 Restricted stock $ 2.3 $ 62.4 Mutual fund awards 0.1 54.0 Total $ 2.4 $ 116.4 Restricted stock and mutual fund awards generally vest and will be recognized using a graded vesting method over a three

Note 12 - Retirement Benefit Pl

Note 12 - Retirement Benefit Plans	6 Months Ended
Note 12 - Retirement Benefit Plans	Jun. 30, 2023
Notes to Financial Statements
Retirement Benefits [Text Block]	Note 12 Retirement Benefit Plans We operate defined contribution retirement benefit plans and defined benefit pension plans. Our primary defined benefit pension plan is the defined benefit section of the Janus Henderson Group UK Pension Scheme (“JHGPS”). Net Periodic Benefit Cost The components of net periodic benefit cost in respect of defined benefit plans for the three six June 30, 2023 2022 Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Interest cost $ (6.9 ) $ (4.1 ) $ (13.7 ) $ (8.6 ) Amortization of prior service cost (0.1 ) (0.1 ) (0.2 ) (0.2 ) Expected return on plan assets 6.8 2.7 13.4 7.2 Net periodic benefit cost $ (0.2 ) $ (1.5 ) $ (0.5 ) $ (1.6 )

Note 13 - Accumulated Other Com

Note 13 - Accumulated Other Comprehensive Loss	6 Months Ended
Note 13 - Accumulated Other Comprehensive Loss	Jun. 30, 2023
Notes to Financial Statements
Comprehensive Income (Loss) Note [Text Block]	Note 13 Accumulated Other Comprehensive Loss Changes in accumulated other comprehensive loss, net of tax for the three six June 30, 2023 2022 Three months ended June 30, 2023 2022 Retirement Retirement Foreign benefit Foreign benefit currency asset, net Total currency asset, net Total Beginning balance $ (536.0 ) $ (70.3 ) $ (606.3 ) $ (401.4 ) $ (32.7 ) $ (434.1 ) Other comprehensive income (loss) 38.4 — 38.4 (182.1 ) — (182.1 ) Reclassifications to net income 2.1 0.1 2.2 4.3 0.1 4.4 Total other comprehensive income (loss) 40.5 0.1 40.6 (177.8 ) 0.1 (177.7 ) Less: other comprehensive loss (income) attributable to noncontrolling interests 1.6 — 1.6 23.6 — 23.6 Ending balance $ (493.9 ) $ (70.2 ) $ (564.1 ) $ (555.6 ) $ (32.6 ) $ (588.2 ) Six months ended June 30, 2023 2022 Retirement Retirement Foreign benefit Foreign benefit currency asset, net Total currency asset, net Total Beginning balance $ (577.3 ) $ (70.4 ) $ (647.7 ) $ (354.2 ) $ (32.8 ) $ (387.0 ) Other comprehensive loss 82.9 — 82.9 (229.9 ) — (229.9 ) Reclassifications to net income 2.1 0.2 2.3 5.1 0.2 5.3 Total other comprehensive loss 85.0 0.2 85.2 (224.8 ) 0.2 (224.6 ) Less: other comprehensive loss (income) attributable to noncontrolling interests (1.6 ) — (1.6 ) 23.4 — 23.4 Ending balance $ (493.9 ) $ (70.2 ) $ (564.1 ) $ (555.6 ) $ (32.6 ) $ (588.2 ) The components of other comprehensive loss, net of tax for the three six June 30, 2023 2022 Three months ended June 30, 2023 2022 Pre-tax Tax Net Pre-tax Tax Net amount impact amount amount impact amount Foreign currency translation adjustments $ 38.8 $ (0.4 ) $ 38.4 $ (184.1 ) $ 2.0 $ (182.1 ) Reclassifications to net income 2.2 — 2.2 4.4 — 4.4 Total other comprehensive loss $ 41.0 $ (0.4 ) $ 40.6 $ (179.7 ) $ 2.0 $ (177.7 ) Six months ended June 30, 2023 2022 Pre-tax Tax Net Pre-tax Tax Net amount impact amount amount impact amount Foreign currency translation adjustments $ 80.3 $ 2.6 $ 82.9 $ (233.1 ) $ 3.2 $ (229.9 ) Reclassifications to net income 2.3 — 2.3 5.3 — 5.3 Total other comprehensive loss $ 82.6 $ 2.6 $ 85.2 $ (227.8 ) $ 3.2 $ (224.6 )

Note 14 - Earnings and Dividend

Note 14 - Earnings and Dividends Per Share	6 Months Ended
Note 14 - Earnings and Dividends Per Share	Jun. 30, 2023
Notes to Financial Statements
Earnings and Dividends Per Share [Text Block]	Note 14 Earnings and Dividends Per Share Earnings Per Share The following is a summary of the earnings per share calculation for the three six June 30, 2023 2022 Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Net income attributable to JHG $ 89.8 $ 96.2 $ 177.2 $ 199.8 Allocation of earnings to participating stock-based awards (2.7 ) (3.0 ) (5.0 ) (5.6 ) Net income attributable to JHG common shareholders $ 87.1 $ 93.2 $ 172.2 $ 194.2 Weighted-average common shares outstanding — basic 160.5 161.9 160.4 163.0 Dilutive effect of nonparticipating stock-based awards 0.2 0.3 0.2 0.4 Weighted-average common shares outstanding — diluted 160.7 162.2 160.6 163.4 Earnings per share: Basic $ 0.54 $ 0.58 $ 1.07 $ 1.19 Diluted $ 0.54 $ 0.57 $ 1.07 $ 1.19 Dividends Per Share The payment of cash dividends is within the discretion of our Board of Directors and depends on many factors, including, but not The following is a summary of cash dividends declared and paid during the six June 30, 2023 Dividend Date Dividends paid Date per share declared (in US$ millions) paid $ 0.39 February 1, 2023 $ 64.7 February 28, 2023 $ 0.39 May 2, 2023 $ 64.6 May 31, 2023 On August 1, 2023 second 2023 August 30, 2023 August 14, 2023

Note 15 - Commitments and Conti

Note 15 - Commitments and Contingencies	6 Months Ended
Note 15 - Commitments and Contingencies	Jun. 30, 2023
Notes to Financial Statements
Commitments and Contingencies Disclosure [Text Block]	Note 15 Commitments and Contingencies Commitments and contingencies may Litigation and Other Regulatory Matters We are periodically involved in various legal proceedings and other regulatory matters. Sandra Schissler v Janus Henderson US (Holdings) Inc., Janus Henderson Advisory Committee, and John and Jane Does 1 30 On September 9, 2022, Schissler v. Janus Henderson US (Holdings) Inc., et al. 401 September 9, 2016. January 10, 2023, November 23, 2022, two September 9, 2016, September 9, 2022, February 9, 2023, March 13, 2023, March 28, 2023.

Item 5 - Other Information

Item 5 - Other Information	6 Months Ended
Item 5 - Other Information	Jun. 30, 2023
Notes to Financial Statements
Issuer Rule 10b5-1, Material Terms [Text Block]	5. Trading Plans of Directors and Officers During the quarter ended June 30, 2023, no 16 10b5–1 10b5–1 408

Significant Accounting Policies

Significant Accounting Policies (Policies)	6 Months Ended
Significant Accounting Policies (Policies)	Jun. 30, 2023
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	Basis of Presentation In the opinion of management of Janus Henderson Group plc (“JHG,” “the Company,” “we,” “us,” “our” and similar terms), the accompanying unaudited condensed consolidated financial statements contain all normal recurring adjustments necessary to fairly state our financial position, results of operations and cash flows in accordance with accounting principles generally accepted in the United States of America (“GAAP”). Such financial statements have been prepared in accordance with the instructions to Form 10 not 10 December 31, 2022
Reclassification, Comparability Adjustment [Policy Text Block]	Revision of Previously Issued Financial Statements In conjunction with the preparation of our third 2022 2021 2020 2022 not 2022 2022 In the first 2020, first 2020, not first 2022 third 2022 The following tables present line items for the financial statements for the three six June 30, 2022, three March 31, 2022, June 30, 2022, not The impact of the error on the Condensed Consolidated Statements of Comprehensive Income for the three June 30, 2022, Three months ended June 30, 2022 As previously reported Impact of revisions As revised Other non-operating income (expenses), net $ (1.7 ) $ 2.3 $ 0.6 Income (loss) before taxes 29.6 2.3 31.9 Net income (loss) (7.1 ) 2.3 (4.8 ) Net income (loss) attributable to JHG $ 93.9 $ 2.3 $ 96.2 Earnings (loss) per share attributable to JHG common shareholders: Basic $ 0.56 $ 0.02 $ 0.58 Diluted $ 0.56 $ 0.01 $ 0.57 Other comprehensive income (loss), net of tax: Foreign currency translation gains (losses) (175.5 ) (2.3 ) (177.8 ) Other comprehensive income (loss), net of tax (175.4 ) (2.3 ) (177.7 ) Other comprehensive income (loss) attributable to JHG $ (151.8 ) $ (2.3 ) $ (154.1 ) The impact of the error on the Condensed Consolidated Statements of Comprehensive Income for the six June 30, 2022, Six months ended June 30, 2022 As previously reported Impact of revisions As revised Operating expenses: Impairment of goodwill and intangible assets $ 32.8 $ (32.8 ) $ — Total operating expenses 907.0 (32.8 ) 874.2 Operating income (loss) 268.5 32.8 301.3 Other non-operating income (expenses), net (9.5 ) 2.3 (7.2 ) Income (loss) before taxes 111.0 35.1 146.1 Income tax benefit (provision) (59.5 ) (7.9 ) (67.4 ) Net income (loss) 51.5 27.2 78.7 Net income (loss) attributable to JHG $ 172.6 $ 27.2 $ 199.8 Earnings (loss) per share attributable to JHG common shareholders: Basic $ 1.03 $ 0.16 $ 1.19 Diluted $ 1.03 $ 0.16 $ 1.19 Other comprehensive income (loss), net of tax: Foreign currency translation gains (losses) (222.5 ) (2.3 ) (224.8 ) Other comprehensive income (loss), net of tax (222.3 ) (2.3 ) (224.6 ) Other comprehensive income (loss) attributable to JHG $ (198.9 ) $ (2.3 ) $ (201.2 ) Total comprehensive income (loss) $ (170.8 ) $ 24.9 $ (145.9 ) Total comprehensive income (loss) attributable to JHG $ (26.3 ) $ 24.9 $ (1.4 )

Note 1 - Basis of Presentation

Note 1 - Basis of Presentation (Tables)	6 Months Ended
Note 1 - Basis of Presentation (Tables)	Jun. 30, 2023
Notes Tables
Schedule of Error Corrections and Prior Period Adjustments [Table Text Block]	Three months ended June 30, 2022 As previously reported Impact of revisions As revised Other non-operating income (expenses), net $ (1.7 ) $ 2.3 $ 0.6 Income (loss) before taxes 29.6 2.3 31.9 Net income (loss) (7.1 ) 2.3 (4.8 ) Net income (loss) attributable to JHG $ 93.9 $ 2.3 $ 96.2 Earnings (loss) per share attributable to JHG common shareholders: Basic $ 0.56 $ 0.02 $ 0.58 Diluted $ 0.56 $ 0.01 $ 0.57 Other comprehensive income (loss), net of tax: Foreign currency translation gains (losses) (175.5 ) (2.3 ) (177.8 ) Other comprehensive income (loss), net of tax (175.4 ) (2.3 ) (177.7 ) Other comprehensive income (loss) attributable to JHG $ (151.8 ) $ (2.3 ) $ (154.1 ) Six months ended June 30, 2022 As previously reported Impact of revisions As revised Operating expenses: Impairment of goodwill and intangible assets $ 32.8 $ (32.8 ) $ — Total operating expenses 907.0 (32.8 ) 874.2 Operating income (loss) 268.5 32.8 301.3 Other non-operating income (expenses), net (9.5 ) 2.3 (7.2 ) Income (loss) before taxes 111.0 35.1 146.1 Income tax benefit (provision) (59.5 ) (7.9 ) (67.4 ) Net income (loss) 51.5 27.2 78.7 Net income (loss) attributable to JHG $ 172.6 $ 27.2 $ 199.8 Earnings (loss) per share attributable to JHG common shareholders: Basic $ 1.03 $ 0.16 $ 1.19 Diluted $ 1.03 $ 0.16 $ 1.19 Other comprehensive income (loss), net of tax: Foreign currency translation gains (losses) (222.5 ) (2.3 ) (224.8 ) Other comprehensive income (loss), net of tax (222.3 ) (2.3 ) (224.6 ) Other comprehensive income (loss) attributable to JHG $ (198.9 ) $ (2.3 ) $ (201.2 ) Total comprehensive income (loss) $ (170.8 ) $ 24.9 $ (145.9 ) Total comprehensive income (loss) attributable to JHG $ (26.3 ) $ 24.9 $ (1.4 )

Note 3 - Consolidation (Tables)

Note 3 - Consolidation (Tables)	6 Months Ended
Note 3 - Consolidation (Tables)	Jun. 30, 2023
Notes Tables
Consolidated Voting Right Entities VRE [Table Text Block]	June 30, December 31, 2023 2022 Investments $ 242.2 $ 206.0 Cash and cash equivalents 30.9 5.8 Other current assets 12.1 1.8 Accounts payable and accrued liabilities (1.6 ) (1.0 ) Total $ 283.6 $ 212.6 Redeemable noncontrolling interests in consolidated VREs (89.2 ) (35.1 ) JHG's net interest in consolidated VREs $ 194.4 $ 177.5

Note 4 - Investment Securities

Note 4 - Investment Securities (Tables)	6 Months Ended
Note 4 - Investment Securities (Tables)	Jun. 30, 2023
Notes Tables
Investment [Table Text Block]	June 30, December 31, 2023 2022 Current investments: Seeded investment products: Consolidated VIEs $ 464.1 $ 334.3 Consolidated VREs 242.2 206.0 Unconsolidated VIEs and VREs 8.6 4.9 Separately managed accounts 41.1 29.7 Total seeded investment products 756.0 574.9 Investments related to deferred compensation plans 11.5 10.7 Other investments 8.6 10.3 Total current investments $ 776.1 $ 595.9 Non-current investments: Equity method investments 31.5 18.7 Total investments $ 807.6 $ 614.6
Unrealized Gain (Loss) on Investments [Table Text Block]	Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Unrealized gains (losses) on investments held at period end $ 6.7 $ (109.4 ) $ 20.5 $ (141.6 )
Gain (Loss) on Securities [Table Text Block]	Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Seeded investment products and hedges, net $ 9.6 $ (6.7 ) $ 15.0 $ (18.2 ) Third-party ownership interests in seeded investment products 10.6 (101.0 ) 19.2 (121.1 ) Equity method investments (14.5 ) 0.2 (11.5 ) 1.7 Other 1.2 (1.9 ) 1.8 (4.0 ) Investment gains (losses), net $ 6.9 $ (109.4 ) $ 24.5 $ (141.6 )
Cash Flows Related to Investment Securities and Other Assets [Table Text Block]	Six months ended June 30, 2023 2022 Purchases Sales, Purchases Sales, and settlements and Net and settlements and Net settlements maturities cash flow settlements maturities cash flow Investments by consolidated seeded investment products $ (204.8 ) $ 41.8 $ (163.0 ) $ (8.5 ) $ 33.1 $ 24.6 Investments (143.2 ) 64.0 (79.2 ) (40.5 ) 44.2 3.7

Note 5 - Derivative Instrumen_2

Note 5 - Derivative Instruments (Tables)	6 Months Ended
Note 5 - Derivative Instruments (Tables)	Jun. 30, 2023
Notes Tables
Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]	Notional value June 30, 2023 December 31, 2022 Futures $ 626.1 $ 196.8 Credit default swaps 125.2 115.1 Total return swaps 39.8 37.2 Foreign currency forward contracts and swaps 189.2 131.7 Notional value June 30, 2023 December 31, 2022 Futures $ 822.2 $ 141.3 Credit default swaps 2.1 2.2 Total return swaps — 10.4 Interest rate swaps 2.1 — Options — 0.1 Foreign currency forward contracts and swaps 87.2 18.3 Notional value June 30, 2023 December 31, 2022 Foreign currency forward contracts and swaps $ 102.4 $ 74.7
Derivative Instruments, Gain (Loss) [Table Text Block]	Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Futures $ 3.6 $ 21.6 $ (3.1 ) $ 37.0 Credit default swaps (0.6 ) 3.3 (2.5 ) 5.6 Total return swaps (5.7 ) 28.8 (11.7 ) 36.2 Foreign currency forward contracts and swaps 4.3 (2.5 ) 8.8 (9.5 ) Total gains (losses) from derivative instruments $ 1.6 $ 51.2 $ (8.5 ) $ 69.3
Schedule of Derivative Instruments [Table Text Block]	Fair value June 30, 2023 December 31, 2022 Derivative assets $ 6.2 $ 5.3 Derivative liabilities 7.2 4.0

Note 6 - Fair Value Measureme_2

Note 6 - Fair Value Measurements (Tables)	6 Months Ended
Note 6 - Fair Value Measurements (Tables)	Jun. 30, 2023
Notes Tables
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]	Fair value measurements using: Quoted prices in Significant active markets for other Significant identical assets observable unobservable and liabilities inputs inputs (Level 1) (Level 2) (Level 3) Total Assets: Cash equivalents $ 640.5 $ — $ — $ 640.5 Investments: Consolidated VIEs 285.6 174.1 4.4 464.1 Other investments 274.8 37.1 0.1 312.0 Total investments 560.4 211.2 4.5 776.1 Seed hedge derivatives — 6.2 — 6.2 Derivatives used in consolidated seeded investment products — 1.4 — 1.4 Derivatives used in foreign currency hedging program — 1.2 — 1.2 Intech option agreement — — 0.2 0.2 Intech contingent consideration — — 11.9 11.9 Total assets $ 1,200.9 $ 220.0 $ 16.6 $ 1,437.5 Liabilities: Derivatives used in consolidated seeded investment products $ — $ 0.3 $ — $ 0.3 Derivatives used in foreign currency hedging program — 0.6 — 0.6 Securities sold, not yet purchased 1.5 — — 1.5 Seed hedge derivatives — 7.2 — 7.2 Long-term debt (1) — 294.5 — 294.5 Deferred bonuses — — 78.2 78.2 Total liabilities $ 1.5 $ 302.6 $ 78.2 $ 382.3 Fair value measurements using: Quoted prices in Significant active markets for other Significant identical assets observable unobservable and liabilities inputs inputs (Level 1) (Level 2) (Level 3) Total Assets: Cash equivalents $ 688.4 $ — $ — $ 688.4 Investments: Consolidated VIEs 275.4 54.0 4.9 334.3 Other investments 171.9 89.4 0.3 261.6 Total investments 447.3 143.4 5.2 595.9 Seed hedge derivatives — 5.3 — 5.3 Derivatives used in consolidated seeded investment products — 0.1 — 0.1 Derivatives used in foreign currency hedging program — 0.4 — 0.4 Intech option agreement — — 0.8 0.8 Intech contingent consideration — — 12.1 12.1 Volantis contingent consideration — — 0.2 0.2 Total assets $ 1,135.7 $ 149.2 $ 18.3 $ 1,303.2 Liabilities: Derivatives used in consolidated seeded investment products $ — $ 0.6 $ — $ 0.6 Derivatives used in foreign currency hedging program — 1.1 — 1.1 Securities sold, not yet purchased 0.5 — — 0.5 Seed hedge derivatives — 4.0 — 4.0 Long-term debt (1) — 295.4 — 295.4 Deferred bonuses — — 46.5 46.5 Total liabilities $ 0.5 $ 301.1 $ 46.5 $ 348.1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Beginning of period fair value $ 17.8 $ 23.2 $ 18.3 $ 8.8 Intech option agreement — (0.8 ) — 3.1 Contingent consideration from sale of Intech — (0.3 ) — 12.3 Settlement of contingent consideration (0.2 ) — (0.2 ) — Fair value adjustments (0.9 ) (0.3 ) (1.4 ) (1.8 ) Transfers from Level 1 0.2 0.5 0.2 0.5 Transfers to Level 1 — (2.1 ) — (2.1 ) Purchases of securities — 1.2 — 1.0 Sales of securities (0.3 ) — (0.3 ) (0.3 ) Foreign currency translation — (0.3 ) — (0.4 ) End of period fair value $ 16.6 $ 21.1 $ 16.6 $ 21.1
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Beginning of period fair value $ 60.0 $ 34.3 $ 46.5 $ 50.5 Fair value adjustments 1.1 (1.0 ) 2.6 (2.6 ) Vesting of deferred bonuses (1.1 ) (14.4 ) (34.3) (36.0 ) Amortization of deferred bonuses 17.5 10.8 25.9 19.2 Foreign currency translation 0.7 (2.1 ) 1.7 (3.5 ) Additions — — 35.8 — End of period fair value $ 78.2 $ 27.6 $ 78.2 $ 27.6

Note 7 - Goodwill and Intangi_2

Note 7 - Goodwill and Intangible Assets (Tables)	6 Months Ended
Note 7 - Goodwill and Intangible Assets (Tables)	Jun. 30, 2023
Notes Tables
Schedule of Intangible Assets and Goodwill [Table Text Block]	Foreign December 31, currency June 30, 2022 Amortization Disposal translation 2023 Indefinite-lived intangible assets: Investment management agreements $ 2,046.5 $ — $ — $ 16.7 $ 2,063.2 Trademarks 360.0 — — — 360.0 Definite-lived intangible assets: Client relationships 68.9 — — 1.6 70.5 Accumulated amortization (60.7 ) (1.0 ) — (1.7 ) (63.4 ) Net intangible assets $ 2,414.7 $ (1.0 ) $ — $ 16.6 $ 2,430.3 Goodwill $ 1,253.1 $ — $ — $ 34.2 $ 1,287.3 Foreign December 31, currency June 30, 2021 Amortization Disposal translation 2022 Indefinite-lived intangible assets: Investment management agreements $ 2,114.8 $ — $ — $ (38.6 ) $ 2,076.2 Trademarks 366.7 — (4.7 ) — 362.0 Definite-lived intangible assets: Client relationships 168.4 — (84.8 ) (6.0 ) 77.6 Accumulated amortization (107.2 ) (2.6 ) 44.7 5.0 (60.1 ) Net intangible assets $ 2,542.7 $ (2.6 ) $ (44.8 ) $ (39.6 ) $ 2,455.7 Goodwill $ 1,341.5 $ — $ (7.0 ) $ (74.8 ) $ 1,259.7
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	Future amortization Amount 2023 (remainder of year) $ 0.7 2024 0.4 2025 0.4 2026 0.4 2027 0.4 Thereafter 4.8 Total $ 7.1

Note 8 - Debt (Tables)

Note 8 - Debt (Tables)	6 Months Ended
Note 8 - Debt (Tables)	Jun. 30, 2023
Notes Tables
Schedule of Long-Term Debt Instruments [Table Text Block]	June 30, 2023 December 31, 2022 Carrying Fair Carrying Fair value value value value 4.875% Senior Notes due 2025 $ 306.0 $ 294.5 $ 307.5 $ 295.4

Note 9 - Income Taxes (Tables)

Note 9 - Income Taxes (Tables)	6 Months Ended
Note 9 - Income Taxes (Tables)	Jun. 30, 2023
Notes Tables
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Effective tax rate 22.0 % 115.4 % 21.6 % 46.1 %

Note 10 - Noncontrolling Intr_2

Note 10 - Noncontrolling Intrests (Tables)	6 Months Ended
Note 10 - Noncontrolling Intrests (Tables)	Jun. 30, 2023
Notes Tables
Redeemable Noncontrolling Interest [Table Text Block]	June 30, December 31, 2023 2022 Consolidated seeded investment products $ 389.8 $ 233.9
Noncontrolling Interest Increase (Decrease) [Table Text Block]	Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Opening balance $ 384.7 $ 150.7 $ 233.9 $ 148.5 Changes in market value 10.6 (101.0 ) 19.2 (121.1 ) Changes in ownership (4.0 ) 895.0 136.2 917.2 Foreign currency translation (1.5 ) (23.6 ) 0.5 (23.5 ) Closing balance $ 389.8 $ 921.1 $ 389.8 $ 921.1
Nonredeemable Noncontrolling Interests [Table Text Block]	June 30, December 31, 2023 2022 Seed capital investments $ 2.8 $ 2.8

Note 11 - Long-Term Incentive_2

Note 11 - Long-Term Incentive and Employee Compensation (Tables)	6 Months Ended
	Jun. 30, 2023
Notes Tables
Share-Based Payment Arrangement, Activity [Table Text Block]	Three months ended Six months ended June 30, June 30, 2023 2023 Restricted stock $ 2.3 $ 62.4 Mutual fund awards 0.1 54.0 Total $ 2.4 $ 116.4

Note 12 - Retirement Benefit _2

Note 12 - Retirement Benefit Plans (Tables)	6 Months Ended
Note 12 - Retirement Benefit Plans (Tables)	Jun. 30, 2023
Notes Tables
Schedule of Net Benefit Costs [Table Text Block]	Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Interest cost $ (6.9 ) $ (4.1 ) $ (13.7 ) $ (8.6 ) Amortization of prior service cost (0.1 ) (0.1 ) (0.2 ) (0.2 ) Expected return on plan assets 6.8 2.7 13.4 7.2 Net periodic benefit cost $ (0.2 ) $ (1.5 ) $ (0.5 ) $ (1.6 )

Note 13 - Accumulated Other C_2

Note 13 - Accumulated Other Comprehensive Loss (Tables)	6 Months Ended
Note 13 - Accumulated Other Comprehensive Loss (Tables)	Jun. 30, 2023
Notes Tables
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	Three months ended June 30, 2023 2022 Retirement Retirement Foreign benefit Foreign benefit currency asset, net Total currency asset, net Total Beginning balance $ (536.0 ) $ (70.3 ) $ (606.3 ) $ (401.4 ) $ (32.7 ) $ (434.1 ) Other comprehensive income (loss) 38.4 — 38.4 (182.1 ) — (182.1 ) Reclassifications to net income 2.1 0.1 2.2 4.3 0.1 4.4 Total other comprehensive income (loss) 40.5 0.1 40.6 (177.8 ) 0.1 (177.7 ) Less: other comprehensive loss (income) attributable to noncontrolling interests 1.6 — 1.6 23.6 — 23.6 Ending balance $ (493.9 ) $ (70.2 ) $ (564.1 ) $ (555.6 ) $ (32.6 ) $ (588.2 ) Six months ended June 30, 2023 2022 Retirement Retirement Foreign benefit Foreign benefit currency asset, net Total currency asset, net Total Beginning balance $ (577.3 ) $ (70.4 ) $ (647.7 ) $ (354.2 ) $ (32.8 ) $ (387.0 ) Other comprehensive loss 82.9 — 82.9 (229.9 ) — (229.9 ) Reclassifications to net income 2.1 0.2 2.3 5.1 0.2 5.3 Total other comprehensive loss 85.0 0.2 85.2 (224.8 ) 0.2 (224.6 ) Less: other comprehensive loss (income) attributable to noncontrolling interests (1.6 ) — (1.6 ) 23.4 — 23.4 Ending balance $ (493.9 ) $ (70.2 ) $ (564.1 ) $ (555.6 ) $ (32.6 ) $ (588.2 )
Comprehensive Income (Loss) [Table Text Block]	Three months ended June 30, 2023 2022 Pre-tax Tax Net Pre-tax Tax Net amount impact amount amount impact amount Foreign currency translation adjustments $ 38.8 $ (0.4 ) $ 38.4 $ (184.1 ) $ 2.0 $ (182.1 ) Reclassifications to net income 2.2 — 2.2 4.4 — 4.4 Total other comprehensive loss $ 41.0 $ (0.4 ) $ 40.6 $ (179.7 ) $ 2.0 $ (177.7 ) Six months ended June 30, 2023 2022 Pre-tax Tax Net Pre-tax Tax Net amount impact amount amount impact amount Foreign currency translation adjustments $ 80.3 $ 2.6 $ 82.9 $ (233.1 ) $ 3.2 $ (229.9 ) Reclassifications to net income 2.3 — 2.3 5.3 — 5.3 Total other comprehensive loss $ 82.6 $ 2.6 $ 85.2 $ (227.8 ) $ 3.2 $ (224.6 )

Note 14 - Earnings and Divide_2

Note 14 - Earnings and Dividends Per Share (Tables)	6 Months Ended
Note 14 - Earnings and Dividends Per Share (Tables)	Jun. 30, 2023
Notes Tables
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Three months ended Six months ended June 30, June 30, 2023 2022 2023 2022 Net income attributable to JHG $ 89.8 $ 96.2 $ 177.2 $ 199.8 Allocation of earnings to participating stock-based awards (2.7 ) (3.0 ) (5.0 ) (5.6 ) Net income attributable to JHG common shareholders $ 87.1 $ 93.2 $ 172.2 $ 194.2 Weighted-average common shares outstanding — basic 160.5 161.9 160.4 163.0 Dilutive effect of nonparticipating stock-based awards 0.2 0.3 0.2 0.4 Weighted-average common shares outstanding — diluted 160.7 162.2 160.6 163.4 Earnings per share: Basic $ 0.54 $ 0.58 $ 1.07 $ 1.19 Diluted $ 0.54 $ 0.57 $ 1.07 $ 1.19
Dividends Declared [Table Text Block]	Dividend Date Dividends paid Date per share declared (in US$ millions) paid $ 0.39 February 1, 2023 $ 64.7 February 28, 2023 $ 0.39 May 2, 2023 $ 64.6 May 31, 2023

Note 1 - Basis of Presentatio_2

Note 1 - Basis of Presentation (Details Textual) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2020	Jun. 30, 2022
Goodwill, Impairment Loss		$ 123.5	$ 7
Revision of Prior Period, Adjustment [Member]
Goodwill, Impairment Loss	$ 32.8

Note 1 - Basis of Presentatio_3

Note 1 - Basis of Presentation - Impact of Error Corrections on Financial Statements (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Other non-operating income (expenses), net	$ 7	$ 0.6	$ 14.1	$ (7.2)
Income (loss) before taxes	128.6	31.9	250.6	146.1
Net income (loss)	100.4	(4.8)	196.4	78.7
Net income (loss) attributable to JHG	$ 89.8	$ 96.2	$ 177.2	$ 199.8
Earnings (loss) per share attributable to JHG common shareholders:
Basic (in dollars per share)	$ 0.54	$ 0.58	$ 1.07	$ 1.19
Diluted (in dollars per share)	$ 0.54	$ 0.57	$ 1.07	$ 1.19
Other comprehensive income (loss), net of tax:
Foreign currency translation gains (losses)	$ 40.5	$ (177.8)	$ 85	$ (224.8)
Other comprehensive income (loss), net of tax	40.6	(177.7)	85.2	(224.6)
Other comprehensive income (loss) attributable to JHG	42.2	(154.1)	83.6	(201.2)
Total comprehensive income (loss)	141	(182.5)	281.6	(145.9)
Total comprehensive income (loss) attributable to JHG	132	(57.9)	260.8	(1.4)
Operating expenses:
Impairment of goodwill and intangible assets				0
Total operating expenses	398.6	411.6	794	874.2
Operating income (loss)	117.9	143.9	218.3	301.3
Other non-operating income (expenses), net	7	0.6	14.1	(7.2)
Income (loss) before taxes	128.6	31.9	250.6	146.1
Income tax benefit (provision)	(28.2)	(36.7)	(54.2)	(67.4)
Net income (loss)	100.4	(4.8)	196.4	78.7
Net income (loss) attributable to JHG	$ 89.8	96.2	$ 177.2	199.8
Previously Reported [Member]
Other non-operating income (expenses), net		(1.7)		(9.5)
Income (loss) before taxes		29.6		111
Net income (loss)		(7.1)		51.5
Net income (loss) attributable to JHG		$ 93.9		$ 172.6
Earnings (loss) per share attributable to JHG common shareholders:
Basic (in dollars per share)		$ 0.56		$ 1.03
Diluted (in dollars per share)		$ 0.56		$ 1.03
Other comprehensive income (loss), net of tax:
Foreign currency translation gains (losses)		$ (175.5)		$ (222.5)
Other comprehensive income (loss), net of tax		(175.4)		(222.3)
Other comprehensive income (loss) attributable to JHG		(151.8)		(198.9)
Total comprehensive income (loss)				(170.8)
Total comprehensive income (loss) attributable to JHG				(26.3)
Operating expenses:
Impairment of goodwill and intangible assets				32.8
Total operating expenses				907
Operating income (loss)				268.5
Other non-operating income (expenses), net		(1.7)		(9.5)
Income (loss) before taxes		29.6		111
Income tax benefit (provision)				(59.5)
Net income (loss)		(7.1)		51.5
Net income (loss) attributable to JHG		93.9		172.6
Revision of Prior Period, Adjustment [Member]
Other non-operating income (expenses), net		2.3		2.3
Income (loss) before taxes		2.3		35.1
Net income (loss)		2.3		27.2
Net income (loss) attributable to JHG		$ 2.3		$ 27.2
Earnings (loss) per share attributable to JHG common shareholders:
Basic (in dollars per share)		$ 0.02		$ 0.16
Diluted (in dollars per share)		$ 0.01		$ 0.16
Other comprehensive income (loss), net of tax:
Foreign currency translation gains (losses)		$ (2.3)		$ (2.3)
Other comprehensive income (loss), net of tax		(2.3)		(2.3)
Other comprehensive income (loss) attributable to JHG		(2.3)		(2.3)
Total comprehensive income (loss)				24.9
Total comprehensive income (loss) attributable to JHG				24.9
Operating expenses:
Impairment of goodwill and intangible assets				(32.8)
Total operating expenses				(32.8)
Operating income (loss)				32.8
Other non-operating income (expenses), net		2.3		2.3
Income (loss) before taxes		2.3		35.1
Income tax benefit (provision)				(7.9)
Net income (loss)		2.3		27.2
Net income (loss) attributable to JHG		$ 2.3		$ 27.2

Note 2 - Dispositions (Details

Note 2 - Dispositions (Details Textual) $ in Millions		6 Months Ended
Note 2 - Dispositions (Details Textual) $ in Millions	Mar. 31, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	Feb. 03, 2022
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal		$ 0	$ (9.1)
Proceeds from Divestiture of Businesses		0	$ 5
Intech Investment Management LLC [Member] \| Term Note [Member]
Financing Receivable, before Allowance for Credit Loss	$ 20	15.9
Financing Receivable Term (Year)	7 years
Number Of Tranches	2
Interest Receivable		0.9
Intech Investment Management LLC [Member] \| Term Note, Tranche One [Member]
Financing Receivable, before Allowance for Credit Loss	$ 10
Investment Interest Rate	5.50%
Intech Investment Management LLC [Member] \| Term Note, Tranche Two [Member]
Financing Receivable, before Allowance for Credit Loss	$ 10
Investment Interest Rate	6%
Intech Investment Management LLC [Member]
Percentage Of Ownership Sold					97%
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal	$ 9.1
Proceeds from Divestiture of Businesses	14.9
Disposal Group Including Discontinued Operation Contingent Consideration	$ 17.5	$ 11.9		$ 12.1

Note 3 - Consolidation - VREs (

Note 3 - Consolidation - VREs (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Investments	$ 312	$ 261.6
Cash and cash equivalents	996.9	1,162.3
Other current assets	132.2	120.3
Accounts payable and accrued liabilities	(212.5)	(232.6)
Variable Rights Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Investments	242.2	206
Cash and cash equivalents	30.9	5.8
Other current assets	12.1	1.8
Accounts payable and accrued liabilities	(1.6)	(1)
Total	283.6	212.6
Redeemable noncontrolling interests in consolidated VREs	(89.2)	(35.1)
JHG's net interest in consolidated VREs	$ 194.4	$ 177.5

Note 4 - Investment Securitie_2

Note 4 - Investment Securities (Details Textual) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Jun. 01, 2023	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Gain (Loss) on Investments		$ 6.9	$ (109.4)	$ 24.5	$ (141.6)
Privacore [Member]
Payments to Acquire Equity Method Investments	$ 25
Equity Method Investment, Ownership Percentage		49%		49%
Long Tail Alpha Investment [Member]
Equity Method Investment, Ownership Percentage		20%		20%
Reclassification of Earnings from an Equity Method Investment [Member]
Gain (Loss) on Investments		$ 12.5		$ 12.5

Note 4 - Investment Securitie_3

Note 4 - Investment Securities - General Disclosure (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Seeded investment products	$ 756	$ 574.9
Estimated Fair Value	807.6	614.6
Equity method investments	31.5	18.7
Unconsolidated VIEs and VREs [Member]
Seeded investment products	8.6	4.9
Separately Managed Accounts [Member]
Seeded investment products	41.1	29.7
Investments Related to Deferred Compensation Plans [Member]
Estimated Fair Value	11.5	10.7
Other Security Investments [Member]
Estimated Fair Value	8.6	10.3
Current Investments [Member]
Estimated Fair Value	776.1	595.9
Variable Interest Entity, Primary Beneficiary [Member]
Seeded investment products	464.1	334.3
Voting Rights Entity, Primary Beneficiary Aggregated Disclosure [Member]
Seeded investment products	$ 242.2	$ 206

Note 4 - Investment Securitie_4

Note 4 - Investment Securities - Net Unrealized Gains (Losses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Securities Investment [Member]
Unrealized gains (losses) on investments held at period end	$ 6.7	$ (109.4)	$ 20.5	$ (141.6)

Note 4 - Investment Securitie_5

Note 4 - Investment Securities - Investment Gains (Losses), Net (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Investment gains (losses), net	$ 6.9	$ (109.4)	$ 24.5	$ (141.6)
Seeded Investment Products and Hedges, Net [Member]
Investment gains (losses), net	9.6	(6.7)	15	(18.2)
Third-party Ownership Interests in Seeded Investment Products [Member]
Investment gains (losses), net	10.6	(101)	19.2	(121.1)
Equity Method Investments [Member]
Investment gains (losses), net	(14.5)	0.2	(11.5)	1.7
Other Security Investments [Member]
Investment gains (losses), net	$ 1.2	$ (1.9)	$ 1.8	$ (4)

Note 4 - Investment Securitie_6

Note 4 - Investment Securities - Cash Flows (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Investments, net	$ (79.2)	$ 3.7
Seeded Investment Products [Member]
Purchases and settlements	(204.8)	(8.5)
Sales, settlements and maturities	41.8	33.1
Investments, net	(163)	24.6
Securities Investment [Member]
Purchases and settlements	(143.2)	(40.5)
Sales, settlements and maturities	64	44.2
Investments, net	$ (79.2)	$ 3.7

Note 5 - Derivative Instrumen_3

Note 5 - Derivative Instruments (Details Textual) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Financial Instruments Sold, Not yet Purchased, Derivatives and Other Contracts	$ 1.5	$ 0.5

Note 5 - Derivative Instrumen_4

Note 5 - Derivative Instruments - Derivative Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Futures [Member]
Notional value of derivative	$ 626.1	$ 196.8
Futures [Member] \| Seeded Investment Products [Member]
Notional value of derivative	822.2	141.3
Foreign Currency, Forward Contracts and Swaps [Member]
Notional value of derivative	189.2	131.7
Foreign Currency, Forward Contracts and Swaps [Member] \| Not Designated as Hedging Instrument, Economic Hedge [Member]
Notional value of derivative	102.4	74.7
Foreign Currency, Forward Contracts and Swaps [Member] \| Seeded Investment Products [Member]
Notional value of derivative	87.2	18.3
Credit Default Swaps [Member]
Notional value of derivative	125.2	115.1
Credit Default Swaps [Member] \| Seeded Investment Products [Member]
Notional value of derivative	2.1	2.2
Total Return Swaps [Member]
Notional value of derivative	39.8	37.2
Total Return Swaps [Member] \| Seeded Investment Products [Member]
Notional value of derivative	0	10.4
Interest Rate Swap [Member] \| Seeded Investment Products [Member]
Notional value of derivative	2.1	0
Options [Member] \| Seeded Investment Products [Member]
Notional value of derivative	$ 0	$ 0.1

Note 5 - Derivative Instrumen_5

Note 5 - Derivative Instruments - Change in Fair Value of Derivatives (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Gain (losses) from derivative instruments	$ 1.6	$ 51.2	$ (8.5)	$ 69.3
Futures [Member]
Gain (losses) from derivative instruments	3.6	21.6	(3.1)	37
Credit Default Swaps [Member]
Gain (losses) from derivative instruments	(0.6)	3.3	(2.5)	5.6
Total Return Swaps [Member]
Gain (losses) from derivative instruments	(5.7)	28.8	(11.7)	36.2
Foreign Currency, Forward Contracts and Swaps [Member]
Gain (losses) from derivative instruments	$ 4.3	$ (2.5)	$ 8.8	$ (9.5)

Note 5 - Derivative Instrumen_6

Note 5 - Derivative Instruments - Derivative Assets and Liabilities (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Derivative assets	$ 6.2	$ 5.3
Derivative liabilities	$ 7.2	$ 4

Note 6 - Fair Value Measureme_3

Note 6 - Fair Value Measurements (Details Textual) - Intech Investment Management LLC [Member] - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Mar. 31, 2022
Disposal Group, Including Discontinued Operation, Contingent Consideration, Options Agreement, Fair Value	$ 0.2	$ 0.8
Disposal Group Including Discontinued Operation Contingent Consideration	$ 11.9	$ 12.1	$ 17.5

Note 6 - Fair Value Measureme_4

Note 6 - Fair Value Measurements - Level of Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2023		Dec. 31, 2022
Total investment securities	$ 312		$ 261.6
Securities sold, not yet purchased	1.5		0.5
Variable Interest Entity, Primary Beneficiary [Member]
Total investment securities	464.1		334.3
Fair Value, Recurring [Member]
Cash equivalents	640.5		688.4
Total investment securities	776.1		595.9
Total assets	1,437.5		1,303.2
Securities sold, not yet purchased	1.5		0.5
Long-term debt	294.5		295.4
Total liabilities	382.3		348.1
Fair Value, Recurring [Member] \| Intech Investment Management LLC [Member]
Contingent consideration	11.9		12.1
Fair Value, Recurring [Member] \| Volantis [Member]
Contingent consideration			0.2
Fair Value, Recurring [Member] \| Seed Hedge Derivatives [Member]
Derivative assets	6.2		5.3
Derivative liabilities	7.2		4
Fair Value, Recurring [Member] \| Derivatives Used in Consolidated Seeded Investment Products [Member]
Derivative assets	1.4		0.1
Derivative liabilities	0.3		0.6
Fair Value, Recurring [Member] \| Foreign Currency, Forward Contracts and Swaps [Member]
Derivative assets	1.2		0.4
Derivative liabilities	0.6		1.1
Fair Value, Recurring [Member] \| Options [Member] \| Intech Investment Management LLC [Member]
Derivative assets	0.2		0.8
Fair Value, Recurring [Member] \| Deferred Bonuses Hedge [Member]
Derivative liabilities	78.2		46.5
Fair Value, Recurring [Member] \| Other Investment Securities [Member]
Total investment securities	312		261.6
Fair Value, Recurring [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Total investment securities	464.1		334.3
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Cash equivalents	640.5		688.4
Total investment securities	560.4		447.3
Total assets	1,200.9		1,135.7
Securities sold, not yet purchased	1.5		0.5
Long-term debt	0		0	[1]
Total liabilities	1.5		0.5
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Intech Investment Management LLC [Member]
Contingent consideration	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Volantis [Member]
Contingent consideration			0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Seed Hedge Derivatives [Member]
Derivative assets	0		0
Derivative liabilities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Derivatives Used in Consolidated Seeded Investment Products [Member]
Derivative assets	0		0
Derivative liabilities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Foreign Currency, Forward Contracts and Swaps [Member]
Derivative assets	0		0
Derivative liabilities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Options [Member] \| Intech Investment Management LLC [Member]
Derivative assets	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Deferred Bonuses Hedge [Member]
Derivative liabilities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Other Investment Securities [Member]
Total investment securities	274.8		171.9
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Total investment securities	285.6		275.4
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Cash equivalents	0		0
Total investment securities	211.2		143.4
Total assets	220		149.2
Securities sold, not yet purchased	0		0
Long-term debt	294.5	[1]	295.4
Total liabilities	302.6		301.1
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Intech Investment Management LLC [Member]
Contingent consideration	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Volantis [Member]
Contingent consideration			0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Seed Hedge Derivatives [Member]
Derivative assets	6.2		5.3
Derivative liabilities	7.2		4
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Derivatives Used in Consolidated Seeded Investment Products [Member]
Derivative assets	1.4		0.1
Derivative liabilities	0.3		0.6
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Foreign Currency, Forward Contracts and Swaps [Member]
Derivative assets	1.2		0.4
Derivative liabilities	0.6		1.1
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Options [Member] \| Intech Investment Management LLC [Member]
Derivative assets	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Deferred Bonuses Hedge [Member]
Derivative liabilities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Other Investment Securities [Member]
Total investment securities	37.1		89.4
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Total investment securities	174.1		54
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Cash equivalents	0		0
Total investment securities	4.5		5.2
Total assets	16.6		18.3
Securities sold, not yet purchased	0		0
Long-term debt	0		0
Total liabilities	78.2		46.5
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Intech Investment Management LLC [Member]
Contingent consideration	11.9		12.1
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Volantis [Member]
Contingent consideration			0.2
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Seed Hedge Derivatives [Member]
Derivative assets	0		0
Derivative liabilities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Derivatives Used in Consolidated Seeded Investment Products [Member]
Derivative assets	0		0
Derivative liabilities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Foreign Currency, Forward Contracts and Swaps [Member]
Derivative assets	0		0
Derivative liabilities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Options [Member] \| Intech Investment Management LLC [Member]
Derivative assets	0.2		0.8
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Deferred Bonuses Hedge [Member]
Derivative liabilities	78.2		46.5
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Other Investment Securities [Member]
Total investment securities	0.1		0.3
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Total investment securities	$ 4.4		$ 4.9

[1]Carried at amortized cost and disclosed at fair value.

Note 6 - Fair Value Measureme_5

Note 6 - Fair Value Measurements - Changes in Level 3 Assets (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Beginning of period fair value	$ 17.8	$ 23.2	$ 18.3	$ 8.8
Intech option agreement	0	(0.8)	0	3.1
Contingent consideration from sale of Intech	0	(0.3)	0	12.3
Settlement of contingent consideration	(0.2)	0	(0.2)	0
Fair value adjustments	(0.9)	(0.3)	(1.4)	(1.8)
Transfers from Level 1	0.2	0.5	0.2	0.5
Transfers to Level 1	0	(2.1)	0	(2.1)
Purchases of securities	0	1.2	0	1
Sales of securities	(0.3)	0	(0.3)	(0.3)
Foreign currency translation	0	(0.3)	0	(0.4)
End of period fair value	$ 16.6	$ 21.1	$ 16.6	$ 21.1

Note 6 - Fair Value Measureme_6

Note 6 - Fair Value Measurements - Changes in Level 3 Liabilities (Details) - Deferred Bonuses [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Beginning of period fair value	$ 60	$ 34.3	$ 46.5	$ 50.5
Fair value adjustments	1.1	(1)	2.6	(2.6)
Vesting of deferred bonuses	(1.1)	(14.4)	(34.3)	(36)
Amortization of deferred bonuses	17.5	10.8	25.9	19.2
Foreign currency translation	0.7	(2.1)	1.7	(3.5)
Additions	0	0	35.8	0
End of period fair value	$ 78.2	$ 27.6	$ 78.2	$ 27.6

Note 7 - Goodwill and Intangi_3

Note 7 - Goodwill and Intangible Assets (Details Textual) - USD ($) $ in Millions	Jun. 30, 2023	Jun. 30, 2022	Mar. 31, 2022
Disposal Group, Including Discontinued Operation, Goodwill	$ 0
Intech Investment Management LLC [Member]
Disposal Group, Including Discontinued Operation, Goodwill			$ 7
Trademarks [Member] \| Intech Investment Management LLC [Member]
Disposal Group, Including Discontinued Operation, Intangible Assets			4.7
Client Relationships [Member]
Disposal Group, Including Discontinued Operation, Intangible Assets	$ 0	$ 84.8
Client Relationships [Member] \| Intech Investment Management LLC [Member]
Disposal Group, Including Discontinued Operation, Intangible Assets			$ 40.1

Note 7 - Goodwill and Intangi_4

Note 7 - Goodwill and Intangible Assets - Intangible Assets and Goodwill (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2020	Jun. 30, 2023	Jun. 30, 2022
Intangible assets, amortization		$ (1)	$ (2.6)
Accumulated amortization, balance		(60.7)	(107.2)
Accumulated amortization, disposals		0
Foreign currency translation		(1.7)	5
Net intangible assets, balance		2,414.7	2,542.7
Net intangible assets, disposals		0
Net intangible assets		16.6	(39.6)
Goodwill, balance		1,253.1	1,341.5
Goodwill, disposals		0
Goodwill, foreign currency translation		34.2	(74.8)
Intangible assets, impairment			(44.8)
Accumulated amortization, balance		(63.4)	(60.1)
Net intangible assets, balance		2,430.3	2,455.7
Goodwill impairment	$ (123.5)		(7)
Goodwill, balance		1,287.3	1,259.7
Client Relationships [Member]
Intangible assets, disposals		0	(84.8)
Foreign currency translation		1.6	(6)
Balance		68.9	168.4
Intangible assets, amortization		0	0
Client relationships		1.6	(6)
Balance		70.5	77.6
Investment Management Agreements [Member]
Balance		2,046.5	2,114.8
Intangible assets, disposals		0
Foreign currency translation		16.7	(38.6)
Client relationships		16.7	(38.6)
Intangible assets, impairment			0
Balance		2,063.2	2,076.2
Trademarks [Member]
Balance		360	366.7
Intangible assets, disposals		0
Foreign currency translation		0	0
Client relationships		0	0
Intangible assets, impairment			(4.7)
Balance		$ 360	$ 362

Note 7 - Goodwill and Intangi_5

Note 7 - Goodwill and Intangible Assets - Schedule of Future Amortization (Details) $ in Millions	Jun. 30, 2023 USD ($)
2023 (remainder of year)	$ 0.7
2024	0.4
2025	0.4
2026	0.4
2027	0.4
Thereafter	4.8
Total	$ 7.1

Note 8 - Debt (Details Textual)

Note 8 - Debt (Details Textual) $ in Thousands	6 Months Ended
Note 8 - Debt (Details Textual) $ in Thousands	Jun. 30, 2023 USD ($)	Mar. 31, 2023
Revolving Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 200,000
Line of Credit Facility, Option for Additional Capacity, Additional Borrowing Capacity	$ 50,000
Line of Credit Facility, Covenant Terms Financing Leverage Ratio, Upper Range Limit	3
Long-Term Line of Credit, Total	$ 0
Senior Notes, 4.876 Percent, Due 2025 [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.875%	4.875%
Debt Instrument, Face Amount	$ 300,000
Debt Instrument, Unamortized Premium	$ 6,000

Note 8 - Debt - Schedule of Deb

Note 8 - Debt - Schedule of Debt (Details) - Senior Notes, 4.876 Percent, Due 2025 [Member] - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Long-term debt	$ 306	$ 307.5
Long-term debt, fair value	$ 294.5	$ 295.4

Note 9 - Income Taxes (Details

Note 9 - Income Taxes (Details Textual) $ in Millions	Jun. 30, 2023 USD ($)
Unrecognized Tax Benefits	$ 26.6
Maximum [Member]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 8.6

Note 9 - Income Taxes - Schedul

Note 9 - Income Taxes - Schedule of Effective Income Tax Rate (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Effective tax rate	22%	115.40%	21.60%	46.10%

Note 10 - Noncontrolling Intere

Note 10 - Noncontrolling Interests - Redeemable Noncontrolling Interest (Details) - USD ($) $ in Millions	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Total redeemable noncontrolling interests	$ 389.8	$ 384.7	$ 233.9	$ 921.1	$ 150.7	$ 148.5
Consolidated Entity, Excluding VIE [Member]
Total redeemable noncontrolling interests	$ 389.8		$ 233.9

Note 10 - Noncontrolling Inte_2

Note 10 - Noncontrolling Interests - Schedule of Changes in Noncontrolling Interests (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Opening balance	$ 384.7	$ 150.7	$ 233.9	$ 148.5
Changes in market value	10.6	(101)	19.2	(121.1)
Changes in ownership	(4)	895	136.2	917.2
Foreign currency translation	(1.5)	(23.6)	0.5	(23.5)
Closing balance	$ 389.8	$ 921.1	$ 389.8	$ 921.1

Note 10 - Noncontrolling Inte_3

Note 10 - Noncontrolling Interests - Nonredeemable Noncontrolling Interests (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Noncontrolling interests	$ 2.8	$ 2.8

Note 11 - Long-Term Incentive_3

Note 11 - Long-Term Incentive and Employee Compensation - Award Activity (Details) - shares shares in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2023
Awards granted (in shares)	2.4	116.4
Restricted Stock [Member]
Awards granted (in shares)	2.3	62.4
Mutual Fund Awards [Member]
Awards granted (in shares)	0.1	54

Note 12 - Retirement Benefit _3

Note 12 - Retirement Benefit Plans - Actuarial Gains (Losses), Benefit Cost, Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Interest cost	$ (6.9)	$ (4.1)	$ (13.7)	$ (8.6)
Amortization of prior service cost	(0.1)	(0.1)	(0.2)	(0.2)
Expected return on plan assets	6.8	2.7	13.4	7.2
Net periodic benefit cost	$ (0.2)	$ (1.5)	$ (0.5)	$ (1.6)

Note 13 - Accumulated Other C_3

Note 13 - Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Beginning balance			$ 4,359.8
Other comprehensive income (loss), net of tax	$ 40.6	$ (177.7)	85.2	$ (224.6)
Less: other comprehensive loss (income) attributable to noncontrolling interests	(1.6)	(23.6)	1.6	(23.4)
Ending balance	4,479		4,479
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Beginning balance	(536)	(401.4)	(577.3)	(354.2)
Other comprehensive income (loss)	38.4	(182.1)	82.9	(229.9)
Reclassifications to net income	2.1	4.3	2.1	5.1
Other comprehensive income (loss), net of tax	40.5	(177.8)	85	(224.8)
Less: other comprehensive loss (income) attributable to noncontrolling interests	1.6	23.6	(1.6)	23.4
Ending balance	(493.9)	(555.6)	(493.9)	(555.6)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Beginning balance	(70.3)	(32.7)	(70.4)	(32.8)
Other comprehensive income (loss)	0	0	0	0
Reclassifications to net income	0.1	0.1	0.2	0.2
Other comprehensive income (loss), net of tax	0.1	0.1	0.2	0.2
Less: other comprehensive loss (income) attributable to noncontrolling interests	0	0	0	0
Ending balance	(70.2)	(32.6)	(70.2)	(32.6)
AOCI Attributable to Parent [Member]
Beginning balance	(606.3)	(434.1)	(647.7)	(387)
Other comprehensive income (loss)	38.4	(182.1)	82.9	(229.9)
Reclassifications to net income	2.2	4.4	2.3	5.3
Other comprehensive income (loss), net of tax	40.6	(177.7)	85.2	(224.6)
Less: other comprehensive loss (income) attributable to noncontrolling interests	1.6	23.6	(1.6)	23.4
Ending balance	$ (564.1)	$ (588.2)	$ (564.1)	$ (588.2)

Note 13 - Accumulated Other C_4

Note 13 - Accumulated Other Comprehensive Loss - Schedule of Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Total other comprehensive loss, pre tax	$ 41	$ (179.7)	$ 82.6	$ (227.8)
Total other comprehensive loss, tax	(0.4)	2	2.6	3.2
Total other comprehensive loss, net	40.6	(177.7)	85.2	(224.6)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Total other comprehensive loss, pre tax	38.8	(184.1)	80.3	(233.1)
Total other comprehensive loss, tax	(0.4)	2	2.6	3.2
Total other comprehensive loss, net	38.4	(182.1)	82.9	(229.9)
Reclassification to Net Income [Member]
Total other comprehensive loss, pre tax	2.2	4.4	2.3	5.3
Total other comprehensive loss, tax	0	0	0	0
Total other comprehensive loss, net	$ 2.2	$ 4.4	$ 2.3	$ 5.3

Note 14 - Earnings and Divide_3

Note 14 - Earnings and Dividends Per Share (Details Textual) - $ / shares	Aug. 01, 2023	May 02, 2023	Feb. 28, 2023
Common Stock, Dividends, Per Share, Declared (in dollars per share)		$ 0.39	$ 0.39
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)	$ 0.39

Note 14 - Earnings and Divide_4

Note 14 - Earnings and Dividends Per Share - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Net income (loss) attributable to JHG	$ 89.8	$ 96.2	$ 177.2	$ 199.8
Allocation of earnings to participating stock-based awards	(2.7)	(3)	(5)	(5.6)
Net income attributable to JHG common shareholders	$ 87.1	$ 93.2	$ 172.2	$ 194.2
Weighted-average common shares outstanding — basic (in shares)	160.5	161.9	160.4	163
Dilutive effect of nonparticipating stock-based awards (in shares)	0.2	0.3	0.2	0.4
Weighted-average common shares outstanding — diluted (in shares)	160.7	162.2	160.6	163.4
Basic (in dollars per share)	$ 0.54	$ 0.58	$ 1.07	$ 1.19
Diluted (in dollars per share)	$ 0.54	$ 0.57	$ 1.07	$ 1.19

Note 14 - Earnings and Divide_5

Note 14 - Earnings and Dividends Per Share - Dividends Declared (Details) - USD ($) $ / shares in Units, $ in Millions			6 Months Ended
	May 02, 2023	Feb. 28, 2023	Jun. 30, 2023	Jun. 30, 2022
Dividend per share (in dollars per share)	$ 0.39	$ 0.39
Dividends paid	$ 64.6	$ 64.7	$ 129.3	$ 129.8