Janus Henderson (JHG) 10-Q2 May 242024 Q1 Quarterly reportFinancial data

Company Profile

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
Document And Entity Information - shares	Mar. 31, 2024	Apr. 30, 2024
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	Q1
Document Fiscal Year Focus	2024
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
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	44
Local Phone Number	(0) 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		160,461,846

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 904.7	$ 1,152.4
Investments	240.7	334.2
Fees and other receivables	268.4	294
OEIC and unit trust receivables	183.4	94.6
Other current assets	120.2	174.5
Total current assets	2,229.7	2,455.6
Non-current assets:
Property, equipment and software, net	41.7	44.2
Intangible assets, net	2,426.7	2,431.3
Goodwill	1,282.2	1,290.3
Retirement benefit asset, net	87.4	87.6
Other non-current assets	202.4	187.6
Total assets	6,270.1	6,496.6
Current liabilities:
Accounts payable and accrued liabilities	206.5	231.4
Current portion of accrued compensation, benefits and staff costs	165.3	297.9
OEIC and unit trust payables	191.9	98.5
Total current liabilities	568.4	631
Non-current liabilities:
Accrued compensation, benefits and staff costs	15.2	45
Long-term debt	303.9	304.6
Deferred tax liabilities, net	569.2	570.8
Retirement benefit obligations, net	2.3	2.3
Other non-current liabilities	109	87.4
Total liabilities	1,568	1,641.1
Commitments and contingencies (See Note 14)
REDEEMABLE NONCONTROLLING INTERESTS	274.7	317.2
EQUITY
Common stock, $1.50 par value; 480,000,000 shares authorized, and 160,674,907 and 163,338,035 shares issued and outstanding as of March 31, 2024, and December 31, 2023, respectively	241	245
Additional paid-in capital	3,670	3,722.3
Treasury shares, 42,586 and 41,444 shares held at March 31, 2024, and December 31, 2023, respectively	(1.1)	(1.1)
Accumulated other comprehensive loss, net of tax	(607.7)	(563.6)
Retained earnings	1,125	1,135.5
Total shareholders’ equity	4,427.2	4,538.1
Nonredeemable noncontrolling interests	0.2	0.2
Total equity	4,427.4	4,538.3
Total liabilities, redeemable noncontrolling interests and equity	6,270.1	6,496.6
Variable Interest Entity, Primary Beneficiary [Member]
Current assets:
Cash and cash equivalents	17.6	15.7
Investments	487.7	382.4
Other current assets	7	7.8
Current liabilities:
Accounts payable and accrued liabilities	$ 4.7	$ 3.2

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parentheticals) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Common stock, par value (in dollars per share)	$ 1.5	$ 1.5
Common stock, shares authorized (in shares)	480,000,000	480,000,000
Common stock, shares issued (in shares)	160,674,907	163,338,035
Common stock, shares outstanding (in shares)	160,674,907	163,338,035
Treasury shares (in shares)	42,586	41,444

Condensed Consolidated Statemen

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Total revenue	$ 551.7	$ 495.8
Operating expenses:
Employee compensation and benefits	165.8	140.3
Long-term incentive plans	50.4	55.5
Distribution expenses	122.4	112
Investment administration	12.2	11.6
Marketing	8	8.8
General, administrative and occupancy	68.6	61.1
Depreciation and amortization	5.1	6.1
Total operating expenses	432.5	395.4
Operating income:	119.2	100.4
Interest expense	(3.1)	(3.1)
Investment gains (losses), net	22.5	17.6
Other non-operating income, net	34.6	7.1
Income before taxes	173.2	122
Income tax provision	(32.6)	(26)
Net income	140.6	96
Net income attributable to noncontrolling interests	(10.5)	(8.6)
Net income attributable to JHG	$ 130.1	$ 87.4
Earnings per share attributable to JHG common shareholders:
Basic (in dollars per share)	$ 0.81	$ 0.53
Diluted (in dollars per share)	$ 0.81	$ 0.53
Other comprehensive income (loss), net of tax:
Foreign currency translation gains (losses)	$ (23.6)	$ 44.5
Reclassification adjustment for foreign currency translation gain included in net income	(22)	0
Actuarial gains	0.4	0.1
Other comprehensive income (loss), net of tax	(45.2)	44.6
Other comprehensive loss (income) attributable to noncontrolling interests	1.1	(3.2)
Other comprehensive income (loss) attributable to JHG	(44.1)	41.4
Total comprehensive income	95.4	140.6
Total comprehensive income attributable to noncontrolling interests	(9.4)	(11.8)
Total comprehensive income attributable to JHG	86	128.8
Investment Advice [Member]
Total revenue	459.4	414.6
Investment Performance [Member]
Total revenue	(13.1)	(14.9)
Shareholder Service [Member]
Total revenue	57.2	51.5
Product and Service, Other [Member]
Total revenue	$ 48.2	$ 44.6

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating activities:
Net income	$ 140.6	$ 96
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	5.1	6.1
Deferred income taxes	1.3	1
Stock-based compensation plan expense	17.5	21.6
Reclassification adjustment for foreign currency translation gain included in net income	(22)	0
Investment gains, net	(22.5)	(17.6)
Contributions to pension plans in excess of costs recognized	(0.6)	(0.4)
Other, net	(1.9)	(1.4)
Changes in operating assets and liabilities:
OEIC and unit trust receivables and payables	4.5	0
Other assets	46.5	(22.1)
Other accruals and liabilities	(173.5)	(191.4)
Net operating activities	(5)	(108.2)
Investing activities:
Investments, net	(9.9)	(107.5)
Property, equipment and software	(1.8)	(2)
Investments by consolidated seeded investment products, net	(38.1)	(123.2)
Cash paid on settled seed capital hedges, net	(5.2)	(3.1)
Dividends received from equity method investments	0.7	0.7
Net investing activities	(54.3)	(235.1)
Financing activities:
Purchase of common stock for stock-based compensation plans	(69.9)	(57.5)
Purchase of common stock for the share buyback program	(81.3)	0
Dividends paid to shareholders	(63.2)	(64.7)
Third-party capital invested into consolidated seeded investment products, net	35.2	136.2
Principal payments under capital lease obligations	0	(0.2)
Net financing activities	(179.2)	13.8
Cash and cash equivalents:
Effect of foreign exchange rate changes	(7.3)	15.4
Net change	(245.8)	(314.1)
At beginning of period	1,168.1	1,176.4
At end of period	922.3	862.3
Supplemental cash flow information:
Cash paid for interest	7.3	7.3
Cash paid for income taxes, net of refunds	6.2	14.1
Reconciliation of cash and cash equivalents:
Total cash and cash equivalents	922.3	862.3
Consolidated Entity, Excluding VIE [Member]
Reconciliation of cash and cash equivalents:
Total cash and cash equivalents	904.7	843.5
Variable Interest Entity, Primary Beneficiary [Member]
Reconciliation of cash and cash equivalents:
Total cash and cash equivalents	$ 17.6	$ 18.8

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Changes In Equity (Unaudited) - USD ($) shares in Millions, $ 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, 2022	165.7
Balance at Dec. 31, 2022	$ 248.5	$ 3,706.6	$ (8.3)	$ (647.7)	$ 1,060.7	$ 2.8	$ 4,362.6
Net income	0	0	0	0	87.4	0	87.4
Other comprehensive loss	0	0	0	41.4	0	0	41.4
Reclassification adjustment for foreign currency translation gain included in net income							0
Dividends paid to shareholders	0	0	0	0	(64.7)	0	(64.7)
Purchase of common stock for stock-based compensation plans	0	(57.3)	(0.2)	0	0	0	(57.5)
Purchase of common stock for stock-based compensation plans	0	(57.3)	(0.2)	0	0	0	(57.5)
Vesting of stock-based compensation plans	0	(7.5)	7.4	0	0	0	(0.1)
Stock-based compensation plan expense	0	21.6	0	0	0	0	21.6
Other comprehensive income	$ 0	0	0	41.4	0	0	41.4
Balance (in shares) at Mar. 31, 2023	165.7
Balance at Mar. 31, 2023	$ 248.5	3,663.4	(1.1)	(606.3)	1,083.4	2.8	4,390.7
Balance (in shares) at Dec. 31, 2023	163.3
Balance at Dec. 31, 2023	$ 245	3,722.3	(1.1)	(563.6)	1,135.5	0.2	4,538.3
Net income	0	0	0	0	130.1	0	130.1
Other comprehensive loss	0	0	0	(22.1)	0	0	(22.1)
Reclassification adjustment for foreign currency translation gain included in net income	0	0	0	(22)	0	0	(22)
Dividends paid to shareholders	$ 0		0	0	(63.3)	0	(63.2)
Dividends paid to shareholders		0.1
Purchase of common stock for the share buyback program (in shares)	(2.6)
Purchase of common stock for the share buyback program	$ (4)	0	0	0	(77.3)	0	(81.3)
Purchase of common stock for stock-based compensation plans	0	(69.5)	(0.4)	0	0	0	(69.9)
Purchase of common stock for stock-based compensation plans	0	(69.5)	(0.4)	0	0	0	(69.9)
Vesting of stock-based compensation plans	0	(0.4)	0.4	0	0	0	0
Stock-based compensation plan expense	0	17.5	0	0	0	0	17.5
Other comprehensive income	$ 0	0	0	(22.1)	0	0	(22.1)
Balance (in shares) at Mar. 31, 2024	160.7
Balance at Mar. 31, 2024	$ 241	$ 3,670	$ (1.1)	$ (607.7)	$ 1,125	$ 0.2	$ 4,427.4

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Changes In Equity (Unaudited) (Parentheticals) - $ / shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Dividends paid (in dollars per share)	$ 0.39	$ 0.39
Dividends paid (in dollars per share)	$ 0.39	$ 0.39

Note 1 - Basis of Presentation

Note 1 - Basis of Presentation	3 Months Ended
Note 1 - Basis of Presentation	Mar. 31, 2024
Notes to Financial Statements
Organization, Consolidation and Presentation of Financial Statements Disclosure [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, 2023 Recent Accounting Pronouncements In November 2023, 2023 07, 280 2023 07 January 1, 2024, January 1, 2025. not In December 2023, 2023 09, 740 2023 09 January 1, 2025. not

Note 2 - Consolidation

Note 2 - Consolidation	3 Months Ended
Note 2 - Consolidation	Mar. 31, 2024
Notes to Financial Statements
Variable Interest Entities Voting Rights Entities Consolidation Disclosure [Text Block]	Note 2 Consolidation Variable Interest Entities Consolidated Variable Interest Entities Our consolidated variable interest entities (“VIEs”) as of March 31, 2024 December 31, 2023 not may not, third no Unconsolidated Variable Interest Entities The following table presents the carrying value of investments included in our Condensed Consolidated Balance Sheets pertaining to unconsolidated VIEs as of March 31, 2024 December 31, 2023 March 31, December 31, 2024 2023 Unconsolidated VIEs $ 14.5 $ 17.2 Our total exposure to unconsolidated VIEs represents the value of our economic ownership interest in the investments. Voting Rights Entities Consolidated Voting Rights Entities The following table presents the balances related to consolidated voting rights entities (“VREs”) that were recorded in our Condensed Consolidated Balance Sheets, including our net interest in these products, as of March 31, 2024 December 31, 2023 March 31, December 31, 2024 2023 Investments $ 76.1 $ 242.9 Cash and cash equivalents 1.7 6.5 Other current assets 1.6 21.6 Accounts payable and accrued liabilities (1.1 ) (1.1 ) Total $ 78.3 $ 269.9 Redeemable noncontrolling interests in consolidated VREs (15.8 ) (100.9 ) JHG’s net interest in consolidated VREs $ 62.5 $ 169.0 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 The following table presents the carrying value of investments included in our Condensed Consolidated Balance Sheets pertaining to unconsolidated VREs as of March 31, 2024 December 31, 2023 March 31, December 31, 2024 2023 Unconsolidated VREs $ 69.4 $ 9.9 Our total exposure to unconsolidated VREs represents the value of our economic ownership interest in the investments.

Note 3 - Investments

Note 3 - Investments	3 Months Ended
Note 3 - Investments	Mar. 31, 2024
Notes to Financial Statements
Investment [Text Block]	Note 3 Investments Our investments as of March 31, 2024 December 31, 2023 March 31, December 31, 2024 2023 Current investments: Seeded investment products: Consolidated VIEs $ 487.7 $ 382.4 Consolidated VREs 76.1 242.9 Unconsolidated VIEs and VREs 83.9 27.1 Separately managed accounts 45.5 44.1 Total seeded investment products 693.2 696.5 Investments related to deferred compensation plans 28.6 12.0 Other investments 6.6 8.1 Total current investments $ 728.4 $ 716.6 Non-current investments: Equity method investments 27.4 29.5 Total investments $ 755.8 $ 746.1 Investment Gains, Net Investment gains, net in our Condensed Consolidated Statements of Comprehensive Income included the following for the three March 31, 2024 2023 Three months ended March 31, 2024 2023 Seeded investment products and hedges, net $ 11.9 $ 5.4 Third-party ownership interests in seeded investment products 10.5 8.6 Equity method investments (1.4 ) 3.0 Other 1.5 0.6 Investment gains, net $ 22.5 $ 17.6 Net unrealized gains (losses), excluding noncontrolling interests, on seeded investment products and associated derivative instruments still held at period end for the three March 31, 2024 2023 Gains and losses attributable to third not Equity Method Investments Our equity method investment includes a 49% interest in Privacore Capital (“Privacore”). Beginning on January 1, 2025, 60 not 99% not 1% Cash Flows Cash flows related to our investments for the three March 31, 2024 2023 Three months ended March 31, 2024 2023 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 $ (41.1 ) $ 3.0 $ (38.1 ) $ (142.3 ) $ 19.1 $ (123.2 ) Investments (65.7 ) 55.8 (9.9 ) (113.2 ) 5.7 (107.5 )

Note 4 - Derivative Instruments

Note 4 - Derivative Instruments	3 Months Ended
Note 4 - Derivative Instruments	Mar. 31, 2024
Notes to Financial Statements
Derivative Instruments and Hedging Activities Disclosure [Text Block]	Note 4 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. We were party to the following derivative instruments as of March 31, 2024 December 31, 2023 Notional value March 31, 2024 December 31, 2023 Futures $ 503.9 $ 1,018.0 Credit default swaps 155.6 199.7 Total return swaps 56.0 51.8 Foreign currency forward contracts 237.6 176.2 The derivative instruments are not three March 31, 2024 2023 Three months ended March 31, 2024 2023 Futures $ (8.7 ) $ (6.7 ) Credit default swaps (1.4 ) (1.9 ) Total return swaps (4.6 ) (6.0 ) Foreign currency forward contracts and swaps 2.7 4.5 Total gains (losses) from derivative instruments $ (12.0 ) $ (10.1 ) 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 liabilities as of March 31, 2024 December 31, 2023 Fair value March 31, 2024 December 31, 2023 Derivative liabilities $ 13.7 $ 16.7 Derivative assets as of March 31, 2024 December 31, 2023 Derivative Instruments Used in Consolidated Seeded Investment Products Certain of our consolidated seeded investment products use 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, net in our Condensed Consolidated Statements of Comprehensive Income. Our consolidated seeded investment products were party to the following derivative instruments as of March 31, 2024 December 31, 2023 Notional value March 31, 2024 December 31, 2023 Futures $ 119.1 $ 1,555.1 Credit default swaps 3.0 13.2 Foreign currency forward contracts and swaps 121.7 135.3 As of March 31, 2024 December 31, 2023 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 uses 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 March 31, 2024 December 31, 2023 Notional value March 31, 2024 December 31, 2023 Foreign currency forward contracts and swaps $ 66.7 $ 65.3 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 March 31, 2024 December 31, 2023 Changes in fair value of the derivatives are recognized in other non-operating income, net in our Condensed Consolidated Statements of Comprehensive Income. Foreign currency remeasurement is also recognized in other non-operating income, net in our Condensed Consolidated Statements of Comprehensive Income. For the three March 31, 2024 2023

Note 5 - Fair Value Measurement

Note 5 - Fair Value Measurements	3 Months Ended
Note 5 - Fair Value Measurements	Mar. 31, 2024
Notes to Financial Statements
Fair Value Disclosures [Text Block]	Note 5 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 March 31, 2024 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 $ 645.5 $ — $ — $ 645.5 Current investments: Consolidated VIEs 291.9 195.7 0.1 487.7 Other investments 209.9 30.8 — 240.7 Total current investments 501.8 226.5 0.1 728.4 Total assets $ 1,147.3 $ 226.5 $ 0.1 $ 1,373.9 Liabilities: Seed hedge derivatives $ — $ 13.7 $ — $ 13.7 Long-term debt (1) — 297.5 — 297.5 Deferred bonuses — — 59.0 59.0 Total liabilities $ — $ 311.2 $ 59.0 $ 370.2 ( 1 Carried at amortized cost in our Condensed Consolidated Balance Sheets and disclosed in this table 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, 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 $ 894.4 $ — $ — $ 894.4 Current investments: Consolidated VIEs 317.6 64.7 0.1 382.4 Other investments 212.2 122.0 — 334.2 Total current investments 529.8 186.7 0.1 716.6 Seed hedge derivatives — 1.8 — 1.8 Derivatives used in consolidated seeded investment products — 6.7 — 6.7 Privacore option agreement — — 1.0 1.0 Total assets $ 1,424.2 $ 195.2 $ 1.1 $ 1,620.5 Liabilities: Derivatives used in consolidated seeded investment products $ — $ 1.2 $ — $ 1.2 Derivatives used in the foreign currency hedging program — 0.7 — 0.7 Securities sold, not yet purchased 1.7 — — 1.7 Seed hedge derivatives — 16.7 — 16.7 Long-term debt (1) — 298.0 — 298.0 Deferred bonuses — — 117.6 117.6 Total liabilities $ 1.7 $ 316.6 $ 117.6 $ 435.9 ( 1 Carried at amortized cost in our Condensed Consolidated Balance Sheets and disclosed in this table at fair value. Level 1 Our Level 1 Level 2 Our Level 2 2 Level 3 Investments As of March 31, 2024 December 31, 2023 3 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 March 31, 2024 2023 Three months ended March 31, 2024 2023 Beginning of period fair value $ 117.6 $ 46.5 Fair value adjustments 5.5 1.5 Vesting of deferred bonuses (81.5 ) (33.2 ) Amortization of deferred bonuses 17.6 8.4 Foreign currency translation (0.2 ) 1.0 Additions — 35.8 End of period fair value $ 59.0 $ 60.0 Nonrecurring Fair Value Measurements Nonrecurring Level 3 3.

Note 6 - Goodwill and Intangibl

Note 6 - Goodwill and Intangible Assets	3 Months Ended
Note 6 - Goodwill and Intangible Assets	Mar. 31, 2024
Notes to Financial Statements
Goodwill and Intangible Assets Disclosure [Text Block]	Note 6 Goodwill and Intangible Assets The following tables present movements in our intangible assets and goodwill during the three March 31, 2024 2023 Foreign December 31, currency March 31, 2023 Amortization translation 2024 Indefinite-lived intangible assets: Investment management agreements $ 2,064.8 $ — $ (4.2 ) $ 2,060.6 Trademarks 360.0 — — 360.0 Definite-lived intangible assets: Client relationships 68.6 — (1.3 ) 67.3 Accumulated amortization (62.1 ) (0.1 ) 1.0 (61.2 ) Net intangible assets $ 2,431.3 $ (0.1 ) $ (4.5 ) $ 2,426.7 Goodwill $ 1,290.3 $ — $ (8.1 ) $ 1,282.2 Foreign December 31, currency March 31, 2022 Amortization translation 2023 Indefinite-lived intangible assets: Investment management agreements $ 2,046.5 $ — $ 8.1 $ 2,054.6 Trademarks 360.0 — — 360.0 Definite-lived intangible assets: Client relationships 68.9 — 0.7 69.6 Accumulated amortization (60.7 ) (0.5 ) (0.8 ) (62.0 ) Net intangible assets $ 2,414.7 $ (0.5 ) $ 8.0 $ 2,422.2 Goodwill $ 1,253.1 $ — $ 16.6 $ 1,269.7

Note 7 - Debt

Note 7 - Debt	3 Months Ended
Note 7 - Debt	Mar. 31, 2024
Notes to Financial Statements
Debt Disclosure [Text Block]	Note 7 Debt Our debt as of March 31, 2024 December 31, 2023 March 31, 2024 December 31, 2023 Carrying Fair Carrying Fair value value value value 4.875% Senior Notes due 2025 $ 303.9 $ 297.5 $ 304.6 $ 298.0 4.875% 2025 The 4.875% Senior Notes due 2025 “2025 March 31, 2024 February 1 August 1 August 1, 2025. 2025 March 31, 2024 2025 Credit Facility On June 30, 2023, June 30, 2028, two one first second may 3.00x March 31, 2024

Note 8 - Income Taxes

Note 8 - Income Taxes	3 Months Ended
Note 8 - Income Taxes	Mar. 31, 2024
Notes to Financial Statements
Income Tax Disclosure [Text Block]	Note 8 Income Taxes Our effective tax rates for the three March 31, 2024 2023 Three months ended March 31, 2024 2023 Effective tax rate 18.8 % 21.3 % The effective tax rate for the three March 31, 2024 2023 As of March 31, 2024 12 The Organisation for Economic Co-operation and Development has a framework to implement a global minimum corporate tax of 15% 2 2 January 1, 2024, January 1, 2025. June 20, 2023, No. 2 2023 15%. December 31, 2023. 2, 2. March 31, 2024, 2 not

Note 9 - Noncontrolling Interes

Note 9 - Noncontrolling Interests	3 Months Ended
Note 9 - Noncontrolling Interests	Mar. 31, 2024
Notes to Financial Statements
Noncontrolling Interest Disclosure [Text Block]	Note 9 Noncontrolling Interests Redeemable Noncontrolling Interests Redeemable noncontrolling interests as of March 31, 2024 December 31, 2023 March 31, December 31, 2024 2023 Consolidated seeded investment products $ 274.7 $ 317.2 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 March 31, 2024 2023 Three months ended March 31, 2024 2023 Opening balance $ 317.2 $ 233.9 Changes in market value 10.5 8.6 Changes in ownership (51.9 ) 140.2 Foreign currency translation (1.1 ) 2.0 Closing balance $ 274.7 $ 384.7

Note 10 - Long-Term Incentive a

Note 10 - Long-Term Incentive and Employee Compensation	3 Months Ended
Note 10 - Long-Term Incentive and Employee Compensation	Mar. 31, 2024
Notes to Financial Statements
Share-Based Payment Arrangement [Text Block]	Note 10 Long-Term Incentive and Employee Compensation The following table presents restricted stock and mutual fund awards granted during the three March 31, 2024 Three months ended March 31, 2024 Restricted stock $ 55.2 Mutual fund awards 67.0 Total $ 122.2 Restricted stock and mutual fund awards generally vest and will be recognized using a graded vesting method over a three

Note 11 - Retirement Benefit Pl

Note 11 - Retirement Benefit Plans	3 Months Ended
Note 11 - Retirement Benefit Plans	Mar. 31, 2024
Notes to Financial Statements
Retirement Benefits [Text Block]	Note 11 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 March 31, 2024 2023 Three months ended March 31, 2024 2023 Interest cost $ (6.8 ) $ (6.8 ) Amortization of prior service cost (0.1 ) (0.1 ) Amortization of net loss (0.3 ) — Expected return on plan assets 6.9 6.6 Net periodic benefit cost $ (0.3 ) $ (0.3 )

Note 12 - Accumulated Other Com

Note 12 - Accumulated Other Comprehensive Loss	3 Months Ended
Note 12 - Accumulated Other Comprehensive Loss	Mar. 31, 2024
Notes to Financial Statements
Comprehensive Income (Loss) Note [Text Block]	Note 12 Accumulated Other Comprehensive Loss Changes in accumulated other comprehensive loss, net of tax for the three March 31, 2024 2023 Three months ended March 31, 2024 2023 Retirement Retirement Foreign benefit Foreign benefit currency asset, net Total currency asset, net Total Beginning balance $ (478.9 ) $ (84.7 ) $ (563.6 ) $ (577.3 ) $ (70.4 ) $ (647.7 ) Other comprehensive income (loss) (23.6 ) — (23.6 ) 44.5 — 44.5 Reclassifications to net income (1) (22.0 ) 0.4 (21.6 ) — 0.1 0.1 Total other comprehensive income (loss) (45.6 ) 0.4 (45.2 ) 44.5 0.1 44.6 Less: other comprehensive loss (income) attributable to noncontrolling interests 1.1 — 1.1 (3.2 ) — (3.2 ) Ending balance $ (523.4 ) $ (84.3 ) $ (607.7 ) $ (536.0 ) $ (70.3 ) $ (606.3 ) ( 1 The components of other comprehensive income (loss), net of tax for the three March 31, 2024 2023 Three months ended March 31, 2024 2023 Pre-tax Tax Net Pre-tax Tax Net amount impact amount amount impact amount Foreign currency translation adjustments $ (26.4 ) $ 2.8 $ (23.6 ) $ 41.5 $ 3.0 $ 44.5 Reclassifications to net income (21.6 ) — (21.6 ) 0.1 — 0.1 Total other comprehensive income (loss) $ (48.0 ) $ 2.8 $ (45.2 ) $ 41.6 $ 3.0 $ 44.6

Note 13 - Earnings and Dividend

Note 13 - Earnings and Dividends Per Share	3 Months Ended
Note 13 - Earnings and Dividends Per Share	Mar. 31, 2024
Notes to Financial Statements
Earnings and Dividends Per Share [Text Block]	Note 13 Earnings and Dividends Per Share Earnings Per Share The following is a summary of the earnings per share calculation for the three March 31, 2024 2023 Three months ended March 31, 2024 2023 Net income attributable to JHG $ 130.1 $ 87.4 Allocation of earnings to participating stock-based awards (3.0 ) (2.4 ) Net income attributable to JHG common shareholders $ 127.1 $ 85.0 Weighted-average common shares outstanding — basic 157.5 160.2 Dilutive effect of nonparticipating stock-based awards 0.2 0.2 Weighted-average common shares outstanding — diluted 157.7 160.4 Earnings per share: Basic $ 0.81 $ 0.53 Diluted $ 0.81 $ 0.53 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 three March 31, 2024 Dividend Date Dividends paid Date per share declared (in US$ millions) paid $ 0.39 January 31, 2024 $ 63.2 February 28, 2024 On May 1, 2024 first 2024 May 29, 2024 May 13, 2024

Note 14 - Commitments and Conti

Note 14 - Commitments and Contingencies	3 Months Ended
Note 14 - Commitments and Contingencies	Mar. 31, 2024
Notes to Financial Statements
Commitments and Contingencies Disclosure [Text Block]	Note 14 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. September 7, 2023, September 21, 2023, October 12, 2023. January 22, 2024,

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Mar. 31, 2024
Insider Trading Arr Line Items
Material Terms of Trading Arrangement [Text Block]	5. Other Information Trading Plans of Directors and Officers During the quarter ended March 31, 2024 no 16 10b5–1 10b5–1 408
Rule 10b5-1 Arrangement Adopted [Flag]	false
Non-Rule 10b5-1 Arrangement Adopted [Flag]	false
Rule 10b5-1 Arrangement Terminated [Flag]	false
Non-Rule 10b5-1 Arrangement Terminated [Flag]	false

Note 2 - Consolidation (Tables)

Note 2 - Consolidation (Tables)	3 Months Ended
Note 2 - Consolidation (Tables)	Mar. 31, 2024
Notes Tables
Schedule of Variable Interest Entities [Table Text Block]	March 31, December 31, 2024 2023 Unconsolidated VIEs $ 14.5 $ 17.2 March 31, December 31, 2024 2023 Investments $ 76.1 $ 242.9 Cash and cash equivalents 1.7 6.5 Other current assets 1.6 21.6 Accounts payable and accrued liabilities (1.1 ) (1.1 ) Total $ 78.3 $ 269.9 Redeemable noncontrolling interests in consolidated VREs (15.8 ) (100.9 ) JHG’s net interest in consolidated VREs $ 62.5 $ 169.0
Unconsolidated Voting Right Entities VRE [Table Text Block]	March 31, December 31, 2024 2023 Unconsolidated VREs $ 69.4 $ 9.9

Note 3 - Investments (Tables)

Note 3 - Investments (Tables)	3 Months Ended
Note 3 - Investments (Tables)	Mar. 31, 2024
Notes Tables
Investment [Table Text Block]	March 31, December 31, 2024 2023 Current investments: Seeded investment products: Consolidated VIEs $ 487.7 $ 382.4 Consolidated VREs 76.1 242.9 Unconsolidated VIEs and VREs 83.9 27.1 Separately managed accounts 45.5 44.1 Total seeded investment products 693.2 696.5 Investments related to deferred compensation plans 28.6 12.0 Other investments 6.6 8.1 Total current investments $ 728.4 $ 716.6 Non-current investments: Equity method investments 27.4 29.5 Total investments $ 755.8 $ 746.1
Gain (Loss) on Securities [Table Text Block]	Three months ended March 31, 2024 2023 Seeded investment products and hedges, net $ 11.9 $ 5.4 Third-party ownership interests in seeded investment products 10.5 8.6 Equity method investments (1.4 ) 3.0 Other 1.5 0.6 Investment gains, net $ 22.5 $ 17.6
Cash Flows Related to Investment Securities and Other Assets [Table Text Block]	Three months ended March 31, 2024 2023 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 $ (41.1 ) $ 3.0 $ (38.1 ) $ (142.3 ) $ 19.1 $ (123.2 ) Investments (65.7 ) 55.8 (9.9 ) (113.2 ) 5.7 (107.5 )

Note 4 - Derivative Instrumen_2

Note 4 - Derivative Instruments (Tables)	3 Months Ended
Note 4 - Derivative Instruments (Tables)	Mar. 31, 2024
Notes Tables
Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]	Notional value March 31, 2024 December 31, 2023 Futures $ 503.9 $ 1,018.0 Credit default swaps 155.6 199.7 Total return swaps 56.0 51.8 Foreign currency forward contracts 237.6 176.2 Notional value March 31, 2024 December 31, 2023 Futures $ 119.1 $ 1,555.1 Credit default swaps 3.0 13.2 Foreign currency forward contracts and swaps 121.7 135.3 Notional value March 31, 2024 December 31, 2023 Foreign currency forward contracts and swaps $ 66.7 $ 65.3
Derivative Instruments, Gain (Loss) [Table Text Block]	Three months ended March 31, 2024 2023 Futures $ (8.7 ) $ (6.7 ) Credit default swaps (1.4 ) (1.9 ) Total return swaps (4.6 ) (6.0 ) Foreign currency forward contracts and swaps 2.7 4.5 Total gains (losses) from derivative instruments $ (12.0 ) $ (10.1 )
Schedule of Derivative Instruments [Table Text Block]	Fair value March 31, 2024 December 31, 2023 Derivative liabilities $ 13.7 $ 16.7

Note 5 - Fair Value Measureme_2

Note 5 - Fair Value Measurements (Tables)	3 Months Ended
Note 5 - Fair Value Measurements (Tables)	Mar. 31, 2024
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 $ 645.5 $ — $ — $ 645.5 Current investments: Consolidated VIEs 291.9 195.7 0.1 487.7 Other investments 209.9 30.8 — 240.7 Total current investments 501.8 226.5 0.1 728.4 Total assets $ 1,147.3 $ 226.5 $ 0.1 $ 1,373.9 Liabilities: Seed hedge derivatives $ — $ 13.7 $ — $ 13.7 Long-term debt (1) — 297.5 — 297.5 Deferred bonuses — — 59.0 59.0 Total liabilities $ — $ 311.2 $ 59.0 $ 370.2 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 $ 894.4 $ — $ — $ 894.4 Current investments: Consolidated VIEs 317.6 64.7 0.1 382.4 Other investments 212.2 122.0 — 334.2 Total current investments 529.8 186.7 0.1 716.6 Seed hedge derivatives — 1.8 — 1.8 Derivatives used in consolidated seeded investment products — 6.7 — 6.7 Privacore option agreement — — 1.0 1.0 Total assets $ 1,424.2 $ 195.2 $ 1.1 $ 1,620.5 Liabilities: Derivatives used in consolidated seeded investment products $ — $ 1.2 $ — $ 1.2 Derivatives used in the foreign currency hedging program — 0.7 — 0.7 Securities sold, not yet purchased 1.7 — — 1.7 Seed hedge derivatives — 16.7 — 16.7 Long-term debt (1) — 298.0 — 298.0 Deferred bonuses — — 117.6 117.6 Total liabilities $ 1.7 $ 316.6 $ 117.6 $ 435.9
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	Three months ended March 31, 2024 2023 Beginning of period fair value $ 117.6 $ 46.5 Fair value adjustments 5.5 1.5 Vesting of deferred bonuses (81.5 ) (33.2 ) Amortization of deferred bonuses 17.6 8.4 Foreign currency translation (0.2 ) 1.0 Additions — 35.8 End of period fair value $ 59.0 $ 60.0

Note 6 - Goodwill and Intangi_2

Note 6 - Goodwill and Intangible Assets (Tables)	3 Months Ended
Note 6 - Goodwill and Intangible Assets (Tables)	Mar. 31, 2024
Notes Tables
Schedule of Intangible Assets and Goodwill [Table Text Block]	Foreign December 31, currency March 31, 2023 Amortization translation 2024 Indefinite-lived intangible assets: Investment management agreements $ 2,064.8 $ — $ (4.2 ) $ 2,060.6 Trademarks 360.0 — — 360.0 Definite-lived intangible assets: Client relationships 68.6 — (1.3 ) 67.3 Accumulated amortization (62.1 ) (0.1 ) 1.0 (61.2 ) Net intangible assets $ 2,431.3 $ (0.1 ) $ (4.5 ) $ 2,426.7 Goodwill $ 1,290.3 $ — $ (8.1 ) $ 1,282.2 Foreign December 31, currency March 31, 2022 Amortization translation 2023 Indefinite-lived intangible assets: Investment management agreements $ 2,046.5 $ — $ 8.1 $ 2,054.6 Trademarks 360.0 — — 360.0 Definite-lived intangible assets: Client relationships 68.9 — 0.7 69.6 Accumulated amortization (60.7 ) (0.5 ) (0.8 ) (62.0 ) Net intangible assets $ 2,414.7 $ (0.5 ) $ 8.0 $ 2,422.2 Goodwill $ 1,253.1 $ — $ 16.6 $ 1,269.7

Note 7 - Debt (Tables)

Note 7 - Debt (Tables)	3 Months Ended
Note 7 - Debt (Tables)	Mar. 31, 2024
Notes Tables
Schedule of Long-Term Debt Instruments [Table Text Block]	March 31, 2024 December 31, 2023 Carrying Fair Carrying Fair value value value value 4.875% Senior Notes due 2025 $ 303.9 $ 297.5 $ 304.6 $ 298.0

Note 8 - Income Taxes (Tables)

Note 8 - Income Taxes (Tables)	3 Months Ended
Note 8 - Income Taxes (Tables)	Mar. 31, 2024
Notes Tables
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Three months ended March 31, 2024 2023 Effective tax rate 18.8 % 21.3 %

Note 9 - Noncontrolling Inter_2

Note 9 - Noncontrolling Interests (Tables)	3 Months Ended
Note 9 - Noncontrolling Interests (Tables)	Mar. 31, 2024
Notes Tables
Redeemable Noncontrolling Interest [Table Text Block]	March 31, December 31, 2024 2023 Consolidated seeded investment products $ 274.7 $ 317.2
Noncontrolling Interest Increase (Decrease) [Table Text Block]	Three months ended March 31, 2024 2023 Opening balance $ 317.2 $ 233.9 Changes in market value 10.5 8.6 Changes in ownership (51.9 ) 140.2 Foreign currency translation (1.1 ) 2.0 Closing balance $ 274.7 $ 384.7

Note 10 - Long-Term Incentive_2

Note 10 - Long-Term Incentive and Employee Compensation (Tables)	3 Months Ended
	Mar. 31, 2024
Notes Tables
Share-Based Payment Arrangement, Activity [Table Text Block]	Three months ended March 31, 2024 Restricted stock $ 55.2 Mutual fund awards 67.0 Total $ 122.2

Note 11 - Retirement Benefit _2

Note 11 - Retirement Benefit Plans (Tables)	3 Months Ended
Note 11 - Retirement Benefit Plans (Tables)	Mar. 31, 2024
Notes Tables
Schedule of Net Benefit Costs [Table Text Block]	Three months ended March 31, 2024 2023 Interest cost $ (6.8 ) $ (6.8 ) Amortization of prior service cost (0.1 ) (0.1 ) Amortization of net loss (0.3 ) — Expected return on plan assets 6.9 6.6 Net periodic benefit cost $ (0.3 ) $ (0.3 )

Note 12 - Accumulated Other C_2

Note 12 - Accumulated Other Comprehensive Loss (Tables)	3 Months Ended
Note 12 - Accumulated Other Comprehensive Loss (Tables)	Mar. 31, 2024
Notes Tables
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	Three months ended March 31, 2024 2023 Retirement Retirement Foreign benefit Foreign benefit currency asset, net Total currency asset, net Total Beginning balance $ (478.9 ) $ (84.7 ) $ (563.6 ) $ (577.3 ) $ (70.4 ) $ (647.7 ) Other comprehensive income (loss) (23.6 ) — (23.6 ) 44.5 — 44.5 Reclassifications to net income (1) (22.0 ) 0.4 (21.6 ) — 0.1 0.1 Total other comprehensive income (loss) (45.6 ) 0.4 (45.2 ) 44.5 0.1 44.6 Less: other comprehensive loss (income) attributable to noncontrolling interests 1.1 — 1.1 (3.2 ) — (3.2 ) Ending balance $ (523.4 ) $ (84.3 ) $ (607.7 ) $ (536.0 ) $ (70.3 ) $ (606.3 )
Comprehensive Income (Loss) [Table Text Block]	Three months ended March 31, 2024 2023 Pre-tax Tax Net Pre-tax Tax Net amount impact amount amount impact amount Foreign currency translation adjustments $ (26.4 ) $ 2.8 $ (23.6 ) $ 41.5 $ 3.0 $ 44.5 Reclassifications to net income (21.6 ) — (21.6 ) 0.1 — 0.1 Total other comprehensive income (loss) $ (48.0 ) $ 2.8 $ (45.2 ) $ 41.6 $ 3.0 $ 44.6

Note 13 - Earnings and Divide_2

Note 13 - Earnings and Dividends Per Share (Tables)	3 Months Ended
Note 13 - Earnings and Dividends Per Share (Tables)	Mar. 31, 2024
Notes Tables
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Three months ended March 31, 2024 2023 Net income attributable to JHG $ 130.1 $ 87.4 Allocation of earnings to participating stock-based awards (3.0 ) (2.4 ) Net income attributable to JHG common shareholders $ 127.1 $ 85.0 Weighted-average common shares outstanding — basic 157.5 160.2 Dilutive effect of nonparticipating stock-based awards 0.2 0.2 Weighted-average common shares outstanding — diluted 157.7 160.4 Earnings per share: Basic $ 0.81 $ 0.53 Diluted $ 0.81 $ 0.53
Dividends Declared [Table Text Block]	Dividend Date Dividends paid Date per share declared (in US$ millions) paid $ 0.39 January 31, 2024 $ 63.2 February 28, 2024

Note 2 - Consolidation - VIEs (

Note 2 - Consolidation - VIEs (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Investments	$ 240.7	$ 334.2
Cash and cash equivalents	904.7	1,152.4
Other current assets	120.2	174.5
Accounts payable and accrued liabilities	(206.5)	(231.4)
Variable Interest Entity, Primary Beneficiary [Member]
Unconsolidated VIEs	14.5	17.2
Investments	487.7	382.4
Cash and cash equivalents	17.6	15.7
Other current assets	7	7.8
Accounts payable and accrued liabilities	(4.7)	(3.2)
Variable Rights Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Investments	76.1	242.9
Cash and cash equivalents	1.7	6.5
Other current assets	1.6	21.6
Accounts payable and accrued liabilities	(1.1)	(1.1)
Total	78.3	269.9
Redeemable noncontrolling interests in consolidated VREs	(15.8)	(100.9)
JHG’s net interest in consolidated VREs	$ 62.5	$ 169

Note 2 - Consolidation - Uncons

Note 2 - Consolidation - Unconsolidated VREs (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Unconsolidated VREs [Member]
JHG’s net interest in consolidated VREs	$ 69.4	$ 9.9

Note 3 - Investments (Details T

Note 3 - Investments (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Unrealized Gain (Loss) on Investments	$ 28.1	$ (14)
Privacore [Member]
Equity Method Investment, Ownership Percentage	49%

Note 3 - Investments - General

Note 3 - Investments - General Disclosure (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Seeded investment products	$ 693.2	$ 696.5
Estimated Fair Value	755.8	746.1
Equity method investments	27.4	29.5
Unconsolidated VIEs and VREs [Member]
Seeded investment products	83.9	27.1
Separately Managed Accounts [Member]
Seeded investment products	45.5	44.1
Investments Related to Deferred Compensation Plans [Member]
Estimated Fair Value	28.6	12
Other Security Investments [Member]
Estimated Fair Value	6.6	8.1
Current Investments [Member]
Estimated Fair Value	728.4	716.6
Variable Interest Entity, Primary Beneficiary [Member]
Seeded investment products	487.7	382.4
Voting Rights Entity, Primary Beneficiary Aggregated Disclosure [Member]
Seeded investment products	$ 76.1	$ 242.9

Note 3 - Investments - Investme

Note 3 - Investments - Investment Gains (Losses), Net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Investment gains (losses), net	$ 22.5	$ 17.6
Seeded Investment Products and Hedges, Net [Member]
Investment gains (losses), net	11.9	5.4
Third-party Ownership Interests in Seeded Investment Products [Member]
Investment gains (losses), net	10.5	8.6
Equity Method Investments [Member]
Investment gains (losses), net	(1.4)	3
Other Security Investments [Member]
Investment gains (losses), net	$ 1.5	$ 0.6

Note 3 - Investments - Cash Flo

Note 3 - Investments - Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Investments, net	$ (9.9)	$ (107.5)
Seeded Investment Products [Member]
Purchases and settlements	(41.1)	(142.3)
Sales, settlements and maturities	3	19.1
Investments, net	(38.1)	(123.2)
Securities Investment [Member]
Purchases and settlements	(65.7)	(113.2)
Sales, settlements and maturities	55.8	5.7
Investments, net	$ (9.9)	$ (107.5)

Note 4 - Derivative Instrumen_3

Note 4 - Derivative Instruments - Derivative Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Futures [Member]
Notional value of derivative	$ 503.9	$ 1,018
Futures [Member] \| Seeded Investment Products [Member]
Notional value of derivative	119.1	1,555.1
Foreign Currency, Forward Contracts and Swaps [Member]
Notional value of derivative	237.6	176.2
Foreign Currency, Forward Contracts and Swaps [Member] \| Not Designated as Hedging Instrument, Economic Hedge [Member]
Notional value of derivative	66.7	65.3
Foreign Currency, Forward Contracts and Swaps [Member] \| Seeded Investment Products [Member]
Notional value of derivative	121.7	135.3
Credit Default Swaps [Member]
Notional value of derivative	155.6	199.7
Credit Default Swaps [Member] \| Seeded Investment Products [Member]
Notional value of derivative	3	13.2
Total Return Swaps [Member]
Notional value of derivative	$ 56	$ 51.8

Note 4 - Derivative Instrumen_4

Note 4 - Derivative Instruments - Change in Fair Value of Derivatives (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Gain (losses) from derivative instruments	$ (12)	$ (10.1)
Futures [Member]
Gain (losses) from derivative instruments	(8.7)	(6.7)
Credit Default Swaps [Member]
Gain (losses) from derivative instruments	(1.4)	(1.9)
Total Return Swaps [Member]
Gain (losses) from derivative instruments	(4.6)	(6)
Foreign Currency, Forward Contracts and Swaps [Member]
Gain (losses) from derivative instruments	$ 2.7	$ 4.5

Note 4 - Derivative Instrumen_5

Note 4 - Derivative Instruments - Derivative Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Not Designated as Hedging Instrument [Member]
Derivative liabilities	$ 13.7	$ 16.7

Note 5 - Fair Value Measureme_3

Note 5 - Fair Value Measurements - Level of Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2024		Dec. 31, 2023
Total investment securities	$ 240.7		$ 334.2
Variable Interest Entity, Primary Beneficiary [Member]
Total investment securities	487.7		382.4
Fair Value, Recurring [Member]
Cash equivalents	645.5		894.4
Total investment securities	728.4		716.6
Total assets	1,373.9		1,620.5
Long-term debt	297.5		298
Total liabilities	370.2		435.9
Securities sold, not yet purchased			1.7
Fair Value, Recurring [Member] \| Seed Hedge Derivatives [Member]
Derivative assets	13.7		1.8
Derivative liabilities			16.7
Fair Value, Recurring [Member] \| Derivatives Used in Consolidated Seeded Investment Products [Member]
Derivative assets			6.7
Derivative liabilities			1.2
Fair Value, Recurring [Member] \| Privacore [Member]
Derivative assets			1
Fair Value, Recurring [Member] \| Deferred Bonuses Hedge [Member]
Derivative liabilities	59		117.6
Fair Value, Recurring [Member] \| Foreign Currency, Forward Contracts and Swaps [Member]
Derivative assets			0.7
Fair Value, Recurring [Member] \| Other Investment Securities [Member]
Total investment securities	240.7		334.2
Fair Value, Recurring [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Total investment securities	487.7		382.4
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Cash equivalents	645.5		894.4
Total investment securities	501.8		529.8
Total assets	1,147.3		1,424.2
Long-term debt	0		0	[1]
Total liabilities	0		1.7
Securities sold, not yet purchased			1.7
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Seed Hedge Derivatives [Member]
Derivative assets	0		0
Derivative liabilities			0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Derivatives Used in Consolidated Seeded Investment Products [Member]
Derivative assets			0
Derivative liabilities			0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Privacore [Member]
Derivative assets			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] \| Foreign Currency, Forward Contracts and Swaps [Member]
Derivative assets			0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Other Investment Securities [Member]
Total investment securities	209.9		212.2
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Total investment securities	291.9		317.6
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Cash equivalents	0		0
Total investment securities	226.5		186.7
Total assets	226.5		195.2
Long-term debt	297.5	[1]	298
Total liabilities	311.2		316.6
Securities sold, not yet purchased			0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Seed Hedge Derivatives [Member]
Derivative assets	13.7		1.8
Derivative liabilities			16.7
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Derivatives Used in Consolidated Seeded Investment Products [Member]
Derivative assets			6.7
Derivative liabilities			1.2
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Privacore [Member]
Derivative assets			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] \| Foreign Currency, Forward Contracts and Swaps [Member]
Derivative assets			0.7
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Other Investment Securities [Member]
Total investment securities	30.8		122
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Total investment securities	195.7		64.7
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Cash equivalents	0		0
Total investment securities	0.1		0.1
Total assets	0.1		1.1
Long-term debt	0		0
Total liabilities	59		117.6
Securities sold, not yet purchased			0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Seed Hedge Derivatives [Member]
Derivative assets	0		0
Derivative liabilities			0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Derivatives Used in Consolidated Seeded Investment Products [Member]
Derivative assets			0
Derivative liabilities			0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Privacore [Member]
Derivative assets			1
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Deferred Bonuses Hedge [Member]
Derivative liabilities	59		117.6
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Foreign Currency, Forward Contracts and Swaps [Member]
Derivative assets			0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Other Investment Securities [Member]
Total investment securities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Total investment securities	$ 0.1		$ 0.1

[1]Carried at amortized cost in our Consolidated Balance Sheets and disclosed in this table at fair value.

Note 5 - Fair Value Measureme_4

Note 5 - Fair Value Measurements - Changes in Level 3 Liabilities (Details) - Deferred Bonuses [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Beginning of period fair value	$ 117.6	$ 46.5
Fair value adjustments	5.5	1.5
Vesting of deferred bonuses	(81.5)	(33.2)
Amortization of deferred bonuses	17.6	8.4
Foreign currency translation	(0.2)	1
Additions	0	35.8
End of period fair value	$ 59	$ 60

Note 6 - Goodwill and Intangi_3

Note 6 - Goodwill and Intangible Assets - Intangible Assets and Goodwill (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Balance		$ 2,414.7
Foreign currency translation		8
Balance		2,422.2
Intangible assets, amortization	$ (0.1)	(0.5)
Accumulated amortization, balance	(62.1)	60.7
Foreign currency translation, accumulated amortization	1	(0.8)
Accumulated amortization	(61.2)	(62)
Net intangible assets, balance	2,431.3
Net intangible assets	(4.5)
Net intangible assets, balance	2,426.7
Goodwill, balance	1,290.3	1,253.1
Goodwill, foreign currency translation	(8.1)	16.6
Goodwill, balance	1,282.2	1,269.7
Accumulated amortization, balance	62.1	(60.7)
Client Relationships [Member]
Balance		68.9
Foreign currency translation	(1.3)	0.7
Balance	67.3	69.6
Balance	68.6
Intangible assets, amortization	0	0
Investment Management Agreements [Member]
Balance	2,064.8	2,046.5
Foreign currency translation	(4.2)	8.1
Balance	2,060.6	2,054.6
Trademarks [Member]
Balance	360	360
Foreign currency translation	0
Balance	$ 360	$ 360

Note 7 - Debt (Details Textual)

Note 7 - Debt (Details Textual) $ in Thousands	3 Months Ended
Note 7 - Debt (Details Textual) $ in Thousands	Mar. 31, 2024 USD ($)
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%
Debt Instrument, Face Amount	$ 300,000
Debt Instrument, Unamortized Premium	$ 3,900

Note 7 - Debt - Schedule of Deb

Note 7 - Debt - Schedule of Debt (Details) - Senior Notes, 4.876 Percent, Due 2025 [Member] - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Long-term debt	$ 303.9	$ 304.6
Long-term debt, fair value	$ 297.5	$ 298

Note 8 - Income Taxes (Details

Note 8 - Income Taxes (Details Textual) $ in Millions	Mar. 31, 2024 USD ($)
Unrecognized Tax Benefits	$ 26
Maximum [Member]
Unrecognized Tax Benefits	$ 6.5

Note 8 - Income Taxes - Schedul

Note 8 - Income Taxes - Schedule of Effective Income Tax Rate (Details)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Effective tax rate	18.80%	21.30%

Note 9 - Noncontrolling Inter_3

Note 9 - Noncontrolling Interests - Redeemable Noncontrolling Interest (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Total redeemable noncontrolling interests	$ 274.7	$ 317.2	$ 384.7	$ 233.9
Consolidated Entity, Excluding VIE [Member]
Total redeemable noncontrolling interests	$ 274.7	$ 317.2

Note 9 - Noncontrolling Inter_4

Note 9 - Noncontrolling Interests - Schedule of Changes in Noncontrolling Interests (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Opening balance	$ 317.2	$ 233.9
Changes in market value	10.5	8.6
Changes in ownership	(51.9)	140.2
Foreign currency translation	(1.1)	2
Closing balance	$ 274.7	$ 384.7

Note 10 - Long-Term Incentive_3

Note 10 - Long-Term Incentive and Employee Compensation - Award Activity (Details) shares in Millions	3 Months Ended
	Mar. 31, 2024 shares
Awards granted (in shares)	122.2
Restricted Stock [Member]
Awards granted (in shares)	55.2
Mutual Fund Awards [Member]
Awards granted (in shares)	67

Note 11 - Retirement Benefit _3

Note 11 - Retirement Benefit Plans - Actuarial Gains (Losses), Benefit Cost, Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Interest cost	$ (6.8)	$ (6.8)
Amortization of prior service cost	(0.1)	(0.1)
Amortization of net loss	(0.3)	0
Expected return on plan assets	6.9	6.6
Net periodic benefit cost	$ (0.3)	$ (0.3)

Note 12 - Accumulated Other C_3

Note 12 - Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
Balance		$ 4,538.3	$ 4,362.6
Total other comprehensive income (loss)		(45.2)	44.6
Less: other comprehensive loss (income) attributable to noncontrolling interests		(1.1)	3.2
Balance		4,427.4	4,390.7
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
Balance		(478.9)	(577.3)
Other comprehensive income (loss)		(23.6)	44.5
Reclassifications to net income(1)	[1]	(22)	0
Total other comprehensive income (loss)		(45.6)	44.5
Less: other comprehensive loss (income) attributable to noncontrolling interests		1.1	(3.2)
Balance		(523.4)	(536)
Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
Balance		(84.7)	(70.4)
Other comprehensive income (loss)		0	0
Reclassifications to net income(1)	[1]	0.4	0.1
Total other comprehensive income (loss)		0.4	0.1
Less: other comprehensive loss (income) attributable to noncontrolling interests		0	0
Balance		(84.3)	(70.3)
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
Balance		(563.6)	(647.7)
Other comprehensive income (loss)		(23.6)	44.5
Reclassifications to net income(1)	[1]	(21.6)	0.1
Total other comprehensive income (loss)		(45.2)	44.6
Less: other comprehensive loss (income) attributable to noncontrolling interests		1.1	(3.2)
Balance		$ (607.7)	$ (606.3)

[1]Reclassifications to net income are primarily related to the release of accumulated foreign currency translation reserves during the period in which a JHG entity liquidated.

Note 12 - Accumulated Other C_4

Note 12 - Accumulated Other Comprehensive Loss - Schedule of Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Total other comprehensive loss, pre tax	$ (48)	$ 41.6
Total other comprehensive loss, tax	2.8	3
Total other comprehensive loss, net	(45.2)	44.6
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Total other comprehensive loss, pre tax	(26.4)	41.5
Total other comprehensive loss, tax	2.8	3
Total other comprehensive loss, net	(23.6)	44.5
Reclassification to Net Income [Member]
Total other comprehensive loss, pre tax	(21.6)	0.1
Total other comprehensive loss, tax	0	0
Total other comprehensive loss, net	$ (21.6)	$ 0.1

Note 13 - Earnings and Divide_3

Note 13 - Earnings and Dividends Per Share (Details Textual) - $ / shares		3 Months Ended
	May 01, 2024	Mar. 31, 2024
Common Stock, Dividends, Per Share, Declared (in dollars per share)		$ 0.39
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)	$ 0.39

Note 13 - Earnings and Divide_4

Note 13 - Earnings and Dividends Per Share - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Net income attributable to JHG	$ 130.1	$ 87.4
Allocation of earnings to participating stock-based awards	(3)	(2.4)
Net income attributable to JHG common shareholders	$ 127.1	$ 85
Weighted-average common shares outstanding — basic (in shares)	157.5	160.2
Dilutive effect of nonparticipating stock-based awards (in shares)	0.2	0.2
Weighted-average common shares outstanding — diluted (in shares)	157.7	160.4
Basic (in dollars per share)	$ 0.81	$ 0.53
Diluted (in dollars per share)	$ 0.81	$ 0.53

Note 13 - Earnings and Divide_5

Note 13 - Earnings and Dividends Per Share - Dividends Declared (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Dividend per share (in dollars per share)	$ 0.39
Dividends paid	$ 63.2	$ 64.7