Janus Henderson (JHG) 10-Q 31 Jul 19 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Jul. 26, 2019
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Jun. 30, 2019
Entity File Number	001-38103
Entity Registrant Name	JANUS HENDERSON GROUP PLC
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
Country Region	+44
City Area Code	(0) 20
Local Phone Number	7818 1818
Title of 12(b) Security	Common Stock
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		191,647,272
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Entity Central Index Key	0001274173
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Fees and other receivables	$ 285.8	$ 309.2
OEIC and unit trust receivables	171.4	144.4
Other current assets	108.8	69.4
Total current assets	1,859.8	2,019.1
Non-current assets:
Property, equipment and software, net	72.6	69.5
Intangible assets, net	3,089.7	3,123.3
Goodwill	1,477.4	1,478
Retirement benefit asset, net	209.6	206.5
Other non-current assets	151	15.5
Total assets	6,860.1	6,911.9
Current liabilities:
Current portion of accrued compensation, benefits and staff costs	203.8	345.4
OEIC and unit trust payables	178.4	143.3
Total current liabilities	635.4	728.4
Non-current liabilities:
Accrued compensation, benefits and staff costs	43.1	54.7
Long-term debt	317.7	319.1
Deferred tax liabilities, net	727.6	729.9
Retirement benefit obligations, net	3.6	3.7
Other non-current liabilities	158.6	79.2
Total liabilities	1,886	1,915
Commitments and contingencies (See Note 15)
REDEEMABLE NONCONTROLLING INTERESTS	153.6	136.1
EQUITY
Common stock ($1.50 par, 480,000,000 shares authorized and 191,647,272 and 196,412,764 shares issued and outstanding, respectively)	287.5	294.6
Additional paid-in-capital	3,801.6	3,824.5
Treasury shares (3,787,063 and 4,523,802 shares held, respectively)	(147.8)	(170.8)
Accumulated other comprehensive loss, net of tax	(424)	(423.5)
Retained earnings	1,280.8	1,314.5
Total shareholders' equity	4,798.1	4,839.3
Nonredeemable noncontrolling interests	22.4	21.5
Total equity	4,820.5	4,860.8
Total liabilities, redeemable noncontrolling interests and equity	6,860.1	6,911.9
Consolidated excluding VIEs
Current assets:
Cash and cash equivalents	707	880.4
Investment securities	246.8	291.8
Current liabilities:
Accounts payable and accrued liabilities	248.4	233.2
Consolidated VIEs
Current assets:
Cash and cash equivalents	24	36.2
Investment securities	311.1	282.7
Other current assets	4.9	5
Current liabilities:
Accounts payable and accrued liabilities	$ 4.8	$ 6.5

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Common stock, par (in dollars per share)	$ 1.50	$ 1.50
Common stock, shares authorized	480,000,000	480,000,000
Common stock, shares issued	191,647,272	196,412,764
Common stock, shares outstanding	191,647,272	196,412,764
Treasury shares (in shares)	3,787,063	4,523,802

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue:
Total revenue	$ 535.9	$ 592.4	$ 1,055.2	$ 1,180.1
Operating expenses:
Employee compensation and benefits	146.5	151	291.5	297.7
Long-term incentive plans	49.2	55.2	97.6	95.2
Distribution expenses	101.5	114.7	203.4	232
Investment administration	11.1	11.7	22.9	23.1
Marketing	8.1	9.5	15.6	18
General, administrative and occupancy	67.7	59.2	132.9	131.4
Depreciation and amortization	33.3	15.8	48.3	31.2
Total operating expenses	417.4	417.1	812.2	828.6
Operating income	118.5	175.3	243	351.5
Interest expense	(4.2)	(3.9)	(8.3)	(7.7)
Investment gains (losses), net	4.8	(16.6)	18.1	(17.3)
Other non-operating income (expenses), net	28.5	13.9	24.6	52.8
Income before taxes	147.6	168.7	277.4	379.3
Income tax provision	(35.3)	(38.2)	(65.2)	(85.6)
Net income	112.3	130.5	212.2	293.7
Net loss (income) attributable to noncontrolling interests	(2.9)	10.1	(8.7)	12.1
Net income attributable to JHG	$ 109.4	$ 140.6	$ 203.5	$ 305.8
Earnings per share attributable to JHG common shareholders:
Basic (in dollars per share)	$ 0.56	$ 0.70	$ 1.04	$ 1.52
Diluted (in dollars per share)	$ 0.56	$ 0.70	$ 1.03	$ 1.51
Other comprehensive income, net of tax:
Foreign currency translation gains	$ (37.3)	$ (104.7)	$ (0.5)	$ (52)
Other comprehensive loss attributable to noncontrolling interests	0.1	0.6		0.8
Other comprehensive loss attributable to JHG	(37.2)	(104.1)	(0.5)	(51.2)
Total comprehensive income	75	25.8	211.7	241.7
Total comprehensive loss (income) attributable to noncontrolling interests	(2.8)	10.7	(8.7)	12.9
Total comprehensive income attributable to JHG	72.2	36.5	203	254.6
Management fees
Revenue:
Total revenue	446.4	493.5	888.3	996.4
Performance fees
Revenue:
Total revenue	3.5	13.5	(2.1)	9.6
Shareowner servicing fees
Revenue:
Total revenue	38.3	38.7	74.2	77.1
Other revenue
Revenue:
Total revenue	$ 47.7	$ 46.7	$ 94.8	$ 97

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating activities:
Net income	$ 212.2	$ 293.7
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	30.3	31.2
Impairment of intangible asset	18
Deferred income taxes	(0.5)
Stock-based compensation plan expense	38.1	41.2
Impairment of ROU operating asset	4.7
Investment gains (losses), net	(18.1)	17.3
Gain from BNP Paribas transaction		(22.3)
Dai-ichi option fair value adjustments		(24.7)
Contingent consideration fair value adjustment	(20)
Contributions to pension plans in excess of costs recognized	(3.4)	(9)
Other, net	(9)	0.4
Changes in operating assets and liabilities:
OEIC and unit trust receivables and payables	8.2	2.8
Other assets	14.5	118.6
Other accruals and liabilities	(192)	(268.3)
Net operating activities	83	180.9
Proceeds from (purchase of):
Investment securities, net	57.5	43.9
Property, equipment and software	(14.8)	(11.3)
Investment securities by consolidated seeded investment products, net	(22.2)	(16.7)
Proceeds from BNP Paribas transaction, net		36.5
Cash received (paid) on settled hedges, net	(10.7)	3.6
Dividends received from equity-method investments	0.5
Proceeds from sale of Volantis	1.2
Net investing activities	11.5	56
Financing activities:
Proceeds from stock-based compensation plans		0.3
Purchase of common stock for stock-based compensation plans	(38.1)	(84.1)
Purchase of common stock for share buyback program	(106.1)
Dividends paid to shareholders	(138.3)	(134.7)
Repayment of long-term debt		(81.9)
Payment of contingent consideration	(14.1)	(18.8)
Distributions to noncontrolling interests	(0.5)	(3.4)
Third-party sales in consolidated seeded investment products, net	22.2	16.7
Principal payments under capital lease obligations	(0.6)	(0.7)
Net financing activities	(275.5)	(306.6)
Cash and cash equivalents:
Effect of foreign exchange rate changes	(4.6)	(20.7)
Net change	(185.6)	(90.4)
At beginning of period	916.6	794.2
At end of period	731	703.8
Supplemental cash flow information:
Cash paid for interest	7.3	7.4
Cash paid for income taxes, net of refunds	114.7	104.9
Reconciliation of cash and cash equivalents:
Cash and cash equivalents	916.6	794.2
Consolidated VIEs
Cash and cash equivalents:
At end of period	24	34
Reconciliation of cash and cash equivalents:
Cash and cash equivalents	24	34
Consolidated excluding VIEs
Cash and cash equivalents:
At end of period	707	669.8
Reconciliation of cash and cash equivalents:
Cash and cash equivalents	$ 707	$ 669.8

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Millions	Common stock	Additional paid-in-capital	Treasury shares	Accumulated other comprehensive loss	Retained earnings	Nonredeemable noncontrolling interests	Total
Balance at Dec. 31, 2017	$ 300.6	$ 3,842.9	$ (155.8)	$ (304.3)	$ 1,154.1	$ 38.2	$ 4,875.7
Balance (in shares) at Dec. 31, 2017	200,400,000
Increase (Decrease) in Stockholders' Equity
Net income					305.8	(6.8)	299
Other comprehensive loss				(51.2)			(51.2)
Dividends paid to shareholders		0.1			(134.8)		(134.7)
Distributions to noncontrolling interests						(3.1)	(3.1)
Fair value adjustments to redeemable noncontrolling interests					(0.2)		(0.2)
Redemptions of convertible debt		(34)					(34)
Purchase of common stock for stock-based compensation plans		(37.5)	(46.6)				(84.1)
Vesting of stock-based compensation plans		(29.5)	29.5
Stock-based compensation plan expense		41.2					41.2
Proceeds from stock-based compensation plans		0.3					0.3
Balance at Jun. 30, 2018	$ 300.6	3,783.5	(172.9)	(355.5)	1,324.9	28.3	4,908.9
Balance (in shares) at Jun. 30, 2018	200,400,000
Balance at Mar. 31, 2018	$ 300.6	3,786	(198.9)	(251.4)	1,255.9	34.7	4,926.9
Balance (in shares) at Mar. 31, 2018	200,400,000
Increase (Decrease) in Stockholders' Equity
Net income					140.6	(3.4)	137.2
Other comprehensive loss				(104.1)			(104.1)
Dividends paid to shareholders		0.1			(71.7)		(71.6)
Distributions to noncontrolling interests						(3)	(3)
Fair value adjustments to redeemable noncontrolling interests					0.1		0.1
Redemptions of convertible debt		(0.1)					(0.1)
Purchase of common stock for stock-based compensation plans		(0.2)	(1.2)				(1.4)
Vesting of stock-based compensation plans		(27.2)	27.2
Stock-based compensation plan expense		24.8					24.8
Proceeds from stock-based compensation plans		0.1					0.1
Balance at Jun. 30, 2018	$ 300.6	3,783.5	(172.9)	(355.5)	1,324.9	28.3	4,908.9
Balance (in shares) at Jun. 30, 2018	200,400,000
Balance at Dec. 31, 2018	$ 294.6	3,824.5	(170.8)	(423.5)	1,314.5	21.5	$ 4,860.8
Balance (in shares) at Dec. 31, 2018	196,400,000						196,412,764
Increase (Decrease) in Stockholders' Equity
Net income					203.5	1.4	$ 204.9
Other comprehensive loss				(0.5)			(0.5)
Dividends paid to shareholders		0.1			(138.4)		(138.3)
Share buyback program	$ (7.1)				(99)		(106.1)
Share buyback program (in shares)	(4,800,000)
Distributions to noncontrolling interests						(0.5)	(0.5)
Fair value adjustments to redeemable noncontrolling interests					0.2		0.2
Purchase of common stock for stock-based compensation plans		(33.2)	(4.9)				(38.1)
Vesting of stock-based compensation plans		(27.9)	27.9
Stock-based compensation plan expense		38.1					38.1
Balance at Jun. 30, 2019	$ 287.5	3,801.6	(147.8)	(424)	1,280.8	22.4	$ 4,820.5
Balance (in shares) at Jun. 30, 2019	191,600,000						191,647,272
Balance at Mar. 31, 2019	$ 292.7	3,802.1	(165.4)	(386.8)	1,309.9	22.6	$ 4,875.1
Balance (in shares) at Mar. 31, 2019	195,200,000
Increase (Decrease) in Stockholders' Equity
Net income					109.4	0.2	109.6
Other comprehensive loss				(37.2)			(37.2)
Dividends paid to shareholders		0.1			(68.7)		(68.6)
Share buyback program	$ (5.2)				(70)		(75.2)
Share buyback program (in shares)	(3,600,000)
Distributions to noncontrolling interests						(0.4)	(0.4)
Fair value adjustments to redeemable noncontrolling interests					0.2		0.2
Purchase of common stock for stock-based compensation plans		(1.8)	0.8				(1)
Vesting of stock-based compensation plans		(16.8)	16.8
Stock-based compensation plan expense		18					18
Balance at Jun. 30, 2019	$ 287.5	$ 3,801.6	$ (147.8)	$ (424)	$ 1,280.8	$ 22.4	$ 4,820.5
Balance (in shares) at Jun. 30, 2019	191,600,000						191,647,272

Basis of Presentation and Signi

Basis of Presentation and Significant Accounting Policies	6 Months Ended
	Jun. 30, 2019
Basis of Presentation and Significant Accounting Policies	Note 1 — Basis of Presentation and Significant Accounting Policies Basis of Presentation In the opinion of management of Janus Henderson Group plc (“JHG” or “the Group”), the accompanying unaudited condensed consolidated financial statements contain all normal recurring adjustments necessary to fairly state the financial position, results of operations and cash flows of JHG 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-Q pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. These financial statements should be read in conjunction with the annual consolidated financial statements and notes presented in JHG’s Annual Report on Form 10-K for the year ended December 31, 2018. The December 31, 2018, condensed balance sheet data was derived from audited financial statements, but does not include all disclosures required by GAAP. Events subsequent to the balance sheet date have been evaluated for inclusion in the accompanying financial statements through the issuance date and are included in the notes to the condensed consolidated financial statements. Certain prior year amounts in JHG’s Condensed Consolidated Statements of Comprehensive Income have been reclassified to conform to current year presentation. Specifically, revenue amounts related to certain transfer agent and administrative activities performed for investment products that were previously classified in other revenue were reclassified to shareowner servicing fees. There is no change to consolidated total revenue, operating income, net income or cash flows as a result of this change in classification. Recent Accounting Pronouncements Adopted Leases In February 2016, the Financial Accounting Standards Board (“FASB”) issued a new standard on accounting for leases. The new standard represents a significant change to lease accounting and introduces a lessee model that brings leases onto the balance sheet. The standard also aligns certain underlying principles of the new lessor model with those in the FASB’s new revenue recognition standard. Furthermore, the new standard addresses other concerns related to the prior leases model. The standard became effective January 1, 2019. The Group adopted the new standard effective January 1, 2019, using the modified retrospective approach. Comparative prior periods were not adjusted upon adoption, as the Group utilized the practical expedients available under the guidance. Specifically, the Group did not (i) reassess existing contracts for embedded leases, (ii) reassess existing lease agreements for finance or operating classification, or (iii) reassess existing lease agreements in consideration of initial direct costs. Upon adoption, the Group recognized $129.8 million in right-of-use (“ROU”) assets related to its leased property and equipment. Corresponding lease liabilities of $146.4 million were also recognized. The Group’s property leases represent the vast majority of its ROU assets and lease liabilities, with office spaces in Denver and London representing a significant portion of its leased property. The Group’s leases policy follows. Refer to further disclosure in Note 6. Leases Policy — Updated January 1, 2019 The Group determines if an arrangement is a lease at inception. Operating lease ROU assets are included in other non-current assets in the Group’s Condensed Consolidated Balance Sheets. The current and non-current portions of operating lease liabilities are included in accounts payable and accrued liabilities and in other non-current liabilities, respectively. Finance lease ROU assets are included in property, equipment and software, net, and finance lease liabilities are included in other non-current liabilities. ROU assets represent the Group’s right to use an underlying asset for the lease term, and lease liabilities represent the Group’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As most of JHG’s leases do not provide an implicit rate, the Group uses its incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The operating lease ROU asset also includes any lease payments made and excludes lease incentives. The Group’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. Lease expense for lease payments is recognized on a straight-line basis over the lease term. Hedge Accounting In August 2017, the FASB issued an updated standard that amended hedge accounting. The standard expanded the strategies eligible for hedge accounting, changed how companies assess hedge effectiveness and required new disclosures and presentation. The Group adopted the standard effective January 1, 2019. The adoption did not have a material impact on the Group’s results of operations or financial position. Recent Accounting Pronouncements Not Yet Adopted Retirement Benefit Plans In August 2018, the FASB issued an accounting standards update (“ASU”) that modifies the disclosure requirements for employers that sponsor defined benefit pension plans. The ASU removes, adds and clarifies a number of disclosure requirements related to sponsored benefit plans. The standard is effective January 1, 2021, for calendar year-end companies, and early adoption is permitted. The Group is evaluating the effect of adopting this new accounting standard. Implementation Costs — Cloud Computing Arrangements In August 2018, the FASB issued an ASU that aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement with the requirements for implementation costs incurred to develop or obtain internal-use software. The ASU is effective January 1, 2020, for calendar year-end companies and for the interim periods within those years. Early adoption is permitted. The ASU allows either a retrospective or prospective approach to all implementation costs incurred after adoption. The Group is evaluating the effect of adopting this new accounting standard. ​

Consolidation

Consolidation	6 Months Ended
	Jun. 30, 2019
Consolidation	Note 2 — Consolidation Variable Interest Entities Consolidated Variable Interest Entities JHG’s consolidated variable interest entities (“VIEs”) as of June 30, 2019, and December 31, 2018, include certain consolidated seeded investment products in which the Group has an investment and acts as the investment manager. The assets of these VIEs are not available to JHG or the creditors of JHG. JHG may not, under any circumstances, access cash and cash equivalents held by consolidated VIEs to use in its operating activities or otherwise. In addition, the investors in these VIEs have no recourse to the credit of the Group. Unconsolidated Variable Interest Entities At June 30, 2019, and December 31, 2018, JHG’s carrying values of investment securities included on JHG’s Condensed Consolidated Balance Sheets pertaining to unconsolidated VIEs were $3.7 million and $3.1 million, respectively. JHG’s total exposure to unconsolidated VIEs represents the value of its economic ownership interest in the investment securities. Voting Rights Entities Consolidated Voting Rights Entities The following table presents the balances related to consolidated voting rights entities (“VREs”) that were recorded on JHG’s Condensed Consolidated Balance Sheets, including JHG’s net interest in these products (in millions): ​ ​ ​ ​ ​ ​ ​ ​ June 30, December 31, ​ ​ 2019 ​ 2018 Investment securities ​ $ 9.3 ​ $ 13.9 Cash and cash equivalents ​ ​ 0.1 ​ 1.4 Other current assets ​ ​ 0.2 ​ ​ 0.1 Accounts payable and accrued liabilities ​ ​ (0.1) ​ ​ (0.1) Total ​ ​ 9.5 ​ 15.3 Redeemable noncontrolling interests in consolidated VREs ​ ​ (4.3) ​ (6.0) JHG's net interest in consolidated VREs ​ $ 5.2 ​ $ 9.3 ​ JHG’s total exposure to consolidated VREs represents the value of its economic ownership interest in these seeded investment products. JHG may not, under any circumstances, access cash and cash equivalents held by consolidated VREs to use in its operating activities or for any other purpose. Unconsolidated Voting Rights Entities At June 30, 2019, and December 31, 2018, JHG’s carrying values of investment securities included on JHG’s Condensed Consolidated Balance Sheets pertaining to unconsolidated VREs were $28.4 million and $50.7 million, respectively. JHG’s total exposure to unconsolidated VREs represents the value of its economic ownership interest in the investment securities.

Investment Securities

Investment Securities	6 Months Ended
	Jun. 30, 2019
Investment Securities	Note 3 — Investment Securities JHG’s investment securities as of June 30, 2019, and December 31, 2018, are summarized as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, ​ December 31, ​ 2019 2018 Seeded investment products: ​ ​ ​ ​ ​ ​ Consolidated VIEs ​ $ 311.1 ​ $ 282.7 Consolidated VREs ​ ​ 9.3 ​ ​ 13.9 Unconsolidated VIEs and VREs ​ ​ 32.1 ​ ​ 53.8 Separate accounts ​ ​ 56.7 ​ ​ 71.6 Pooled investment funds ​ ​ 10.6 ​ ​ 25.5 Total seeded investment products ​ 419.8 ​ 447.5 Investments related to deferred compensation plans ​ 132.6 ​ 120.3 Other investments ​ ​ 5.5 ​ ​ 6.7 Total investment securities ​ $ 557.9 ​ $ 574.5 ​ ​ Trading Securities Net unrealized gains (losses) on investment securities held as of June 30, 2019 and 2018, are summarized as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ 2019 2018 2019 2018 Unrealized gains (losses) on investment securities held at period end $ 4.6 $ (13.6) $ 15.7 $ (21.5) ​ Derivative Instruments JHG maintains an economic hedge program that uses derivative instruments to mitigate against market volatility of certain seeded investments by using index and commodity futures (“futures”), index swaps, total return swaps (“TRSs”) and credit default swaps. Foreign currency exposures associated with the Group’s seeded investment products are also hedged by using foreign currency forward contracts. The Group also has a net investment hedge related to foreign currency translation on hedged seed investments denominated in currencies other than the Group’s functional currency. JHG was party to the following derivative instruments as of June 30, 2019, and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ Notional Value ​ June 30, 2019 December 31, 2018 Futures ​ $ 103.5 ​ $ 147.1 Credit default swaps ​ ​ 93.0 ​ ​ 133.2 Total return swaps ​ ​ 75.8 ​ ​ 77.2 Foreign currency forward contracts ​ ​ 163.6 ​ ​ 131.8 ​ The derivative instruments are not designated as hedges for accounting purposes, with the exception of certain foreign currency forward contracts used for net investment hedging. Changes in fair value of the futures, index swaps, TRSs and credit default swaps are recognized in investment gains (losses), net on JHG’s Condensed Consolidated Statements of Comprehensive Income. Changes in the fair value of the foreign currency forward contracts designated as hedges for accounting purposes are recognized in other comprehensive income, net of tax on JHG’s Condensed Consolidated Statements of Comprehensive Income. The value of the individual derivative contracts is recognized on a gross basis and included in other current assets or accounts payable and accrued liabilities on JHG’s Condensed Consolidated Balance Sheets, and is immaterial individually and in aggregate. The Group recognized the following net foreign currency translation gains and losses on hedged seed investments denominated in currencies other than the Group’s functional currency and net gains and losses associated with foreign currency forward contracts under net investment hedge accounting for the three and six months ended June 30, 2019 and 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ ​ 2019 2018 2019 2018 Foreign currency translation $ (1.2) $ (3.3) $ (0.9) $ (3.8) Foreign currency forward contracts ​ 1.2 ​ 3.3 ​ 0.9 ​ 3.8 Total ​ $ — ​ $ — ​ $ — ​ $ — ​ Derivative Instruments in Consolidated Seeded Investment Products Certain of the Group’s 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 accounts payable and accrued liabilities on JHG’s Condensed Consolidated Balance Sheets and are immaterial individually and in aggregate. Gains and losses on these derivative instruments are classified within investment gains (losses), net on JHG’s Condensed Consolidated Statements of Comprehensive Income. JHG’s consolidated seeded investment products were party to the following derivative instruments as of June 30, 2019, and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ Notional Value ​ June 30, 2019 December 31, 2018 Futures ​ $ 102.2 ​ $ 267.8 Contracts for differences ​ ​ 10.4 ​ ​ 8.7 Credit default swaps ​ ​ 2.4 ​ ​ 6.2 Total return swaps ​ ​ 37.8 ​ ​ 23.7 Interest rate swaps ​ 26.2 ​ 61.5 Options ​ 0.7 ​ 9.6 Swaptions ​ — ​ 8.3 Foreign currency forward contracts ​ 147.2 ​ 154.9 ​ As of June 30, 2019, certain consolidated seeded investment products sold credit protection through the use of credit default swap contracts. The contracts provide alternative credit risk exposure to individual companies and countries outside of traditional bond markets. The terms of the credit default swap contracts range from one to five years. As sellers in credit default swap contracts, the consolidated seeded investment products would be required to pay the notional value of a referenced debt obligation to the counterparty in the event of a default on the debt obligation by the issuer. The notional value represents the estimated maximum potential undiscounted amount of future payments required upon the occurrence of a credit default event. As of June 30, 2019, and December 31, 2018, the notional values of the agreements totaled $2.3 million and $3.9 million, respectively. The credit default swap contracts include recourse provisions that allow for recovery of a certain percentage of amounts paid upon the occurrence of a credit default event. As of June 30, 2019, and December 31, 2018, the fair value of the credit default swap contracts selling protection was nil and $0.1 million, respectively. Investment Gains (Losses), Net Investment gains (losses), net on JHG’s Condensed Consolidated Statements of Comprehensive Income included the following for the three and six months ended June 30, 2019 and 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ June 30, ​ June 30, ​ ​ 2019 2018 2019 2018 Seeded investment products and derivatives, net ​ $ 3.4 ​ $ (17.4) ​ $ 11.6 ​ $ (18.2) Other ​ 1.4 ​ 0.8 ​ 6.5 ​ 0.9 Investment gains (losses), net ​ $ 4.8 ​ $ (16.6) ​ $ 18.1 ​ $ (17.3) ​ Cash Flows Cash flows related to investment securities for the six months ended June 30, 2019 and 2018, are summarized as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six months ended June 30, ​ ​ 2019 ​ 2018 ​ ​ ​ Sales, ​ ​ Sales, ​ ​ Purchases ​ settlements ​ Purchases ​ settlements ​ ​ and ​ and ​ and ​ and ​ ​ settlements ​ maturities ​ settlements ​ maturities Investment securities ​ $ (269.1) ​ $ 246.9 ​ $ (30.9) ​ $ 58.1 ​

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2019
Fair Value Measurements	Note 4 — Fair Value Measurements The following table presents assets, liabilities and redeemable noncontrolling interests presented in the financial statements or disclosed in the notes to the financial statements at fair value on a recurring basis as of June 30, 2019 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value measurements using: ​ ​ ​ ​ ​ Quoted prices in ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ active markets for ​ ​ ​ ​ ​ ​ ​ ​ identical assets ​ Significant other ​ Significant ​ ​ ​ ​ ​ and liabilities ​ observable inputs ​ unobservable inputs ​ ​ ​ ​ ​ (Level 1) ​ (Level 2) ​ (Level 3) ​ Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 270.5 ​ $ — ​ $ — ​ $ 270.5 Investment securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Consolidated VIEs ​ ​ 132.9 ​ ​ 162.4 ​ ​ 15.8 ​ ​ 311.1 Other investment securities ​ ​ 185.3 ​ ​ 61.5 ​ ​ — ​ ​ 246.8 Total investment securities ​ ​ 318.2 ​ ​ 223.9 ​ ​ 15.8 ​ ​ 557.9 Seed hedge derivatives ​ ​ — ​ 2.1 ​ ​ — ​ 2.1 Volantis contingent consideration ​ — ​ — ​ 3.3 ​ 3.3 Total assets ​ $ 588.7 ​ $ 226.0 ​ $ 19.1 ​ $ 833.8 Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Derivatives in consolidated seeded investment products ​ $ — ​ $ 1.5 ​ $ — ​ $ 1.5 Seed hedge derivatives ​ ​ — ​ ​ 6.4 ​ ​ — ​ ​ 6.4 Long-term debt (1) ​ ​ — ​ ​ 324.3 ​ ​ — ​ ​ 324.3 Deferred bonuses ​ ​ — ​ ​ — ​ ​ 60.7 ​ ​ 60.7 Contingent consideration ​ ​ — ​ ​ — ​ ​ 31.8 ​ ​ 31.8 Total liabilities ​ $ — ​ $ 332.2 ​ $ 92.5 ​ $ 424.7 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Redeemable noncontrolling interests: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Consolidated seeded investment products ​ $ — ​ $ — ​ $ 138.8 ​ $ 138.8 Intech ​ ​ — ​ ​ — ​ ​ 14.8 ​ ​ 14.8 Total redeemable noncontrolling interests ​ $ — ​ $ — ​ $ 153.6 ​ $ 153.6 ​ (1) Carried at amortized cost and disclosed at fair value. ​ The following table presents assets, liabilities and redeemable noncontrolling interests presented in the financial statements or disclosed in the notes to the financial statements at fair value on a recurring basis as of December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value measurements using: ​ ​ ​ ​ ​ Quoted prices in ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ active markets for ​ ​ ​ ​ ​ ​ ​ ​ identical assets ​ Significant other ​ Significant ​ ​ ​ ​ ​ and liabilities ​ observable inputs ​ unobservable inputs ​ ​ ​ ​ ​ (Level 1) ​ (Level 2) ​ (Level 3) ​ Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 381.8 ​ $ — ​ $ — ​ $ 381.8 Investment securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Consolidated VIEs ​ ​ 103.8 ​ ​ 159.7 ​ ​ 19.2 ​ ​ 282.7 Other investment securities ​ ​ 194.5 ​ ​ 97.3 ​ ​ — ​ ​ 291.8 Total investment securities ​ 298.3 ​ 257.0 ​ 19.2 ​ 574.5 Seed hedge derivatives ​ ​ — ​ 3.2 ​ ​ — ​ 3.2 Derivatives in consolidated seeded investment products ​ ​ — ​ ​ 0.9 ​ ​ — ​ ​ 0.9 Contingent consideration ​ ​ — ​ — ​ 3.9 ​ 3.9 Total assets ​ $ 680.1 ​ $ 261.1 ​ $ 23.1 ​ $ 964.3 Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Derivatives in consolidated seeded investment products ​ $ — ​ $ 2.1 ​ $ — ​ $ 2.1 Financial liabilities in consolidated seeded investment products ​ ​ 0.4 ​ ​ — ​ ​ — ​ ​ 0.4 Seed hedge derivatives ​ ​ — ​ ​ 1.1 ​ ​ — ​ ​ 1.1 Long-term debt (1) ​ ​ — ​ ​ 301.4 ​ ​ — ​ ​ 301.4 Deferred bonuses ​ ​ — ​ ​ — ​ ​ 68.5 ​ ​ 68.5 Contingent consideration ​ ​ — ​ ​ — ​ ​ 61.3 ​ ​ 61.3 Total liabilities ​ $ 0.4 ​ $ 304.6 ​ $ 129.8 ​ $ 434.8 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Redeemable noncontrolling interests: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Consolidated seeded investment products ​ $ — ​ $ — ​ $ 121.6 ​ $ 121.6 Intech ​ ​ — ​ ​ — ​ ​ 14.5 ​ ​ 14.5 Total redeemable noncontrolling interests ​ $ — ​ $ — ​ $ 136.1 ​ $ 136.1 ​ (1) Carried at amortized cost and disclosed at fair value. Level 1 Fair Value Measurements JHG’s Level 1 fair value measurements consist mostly of seeded investment products, investments in advised mutual funds, cash equivalents and investments related to deferred compensation plans with quoted market prices in active markets. The fair value level of consolidated seeded investment products is determined by the underlying securities of the product. The fair value level of unconsolidated seeded investment products is determined using the respective net asset value (“NAV”) of each product. Level 2 Fair Value Measurements JHG’s Level 2 fair value measurements consist mostly of consolidated seeded investment products, derivative instruments and JHG’s long-term debt. The fair value of consolidated seeded investment products is determined by the underlying securities of the product. The fair value of JHG’s long-term debt is determined using broker quotes and recent trading activity, which are considered Level 2 inputs. Level 3 Fair Value Measurements Investment Securities As of June 30, 2019, and December 31, 2018, certain securities within consolidated VIEs were valued using significant unobservable inputs, resulting in Level 3 classification. Valuation techniques and significant unobservable inputs used in the valuation of JHG’s material Level 3 assets included within consolidated VIEs as of June 30, 2019, and December 31, 2018, were as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Significant ​ ​ ​ ​ Fair ​ Valuation ​ unobservable ​ ​ As of June 30, 2019 ​ value ​ technique ​ inputs ​ Inputs Investment securities of consolidated VIEs ​ $ 15.8 Discounted Discount rate ​ 15% ​ ​ ​ ​ cash flow EBITDA multiple ​ 16.4 ​ ​ ​ ​ ​ ​ Price-earnings ratio ​ 27.7 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Significant ​ ​ ​ Fair Valuation unobservable ​ Range As of December 31, 2018 ​ value technique inputs ​ (weighted-average) Investment securities of consolidated VIEs ​ $ 19.2 Discounted Discount rate ​ 15% ​ ​ ​ ​ cash flow EBITDA multiple ​ 18.5 ​ ​ ​ ​ ​ ​ Price-earnings ratio ​ 28.4 ​ Contingent Consideration The maximum amount payable and fair value of Geneva Capital Management LLC (“Geneva”), Perennial Fixed Interest Partners Pty Ltd and Perennial Growth Management Pty Ltd (together “Perennial”) and Kapstream Capital Pty Limited (“Kapstream”) contingent consideration are summarized below (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of June 30, 2019 ​ ​ Geneva ​ Perennial ​ Kapstream Maximum amount payable ​ $ 61.3 ​ $ 15.8 ​ $ 13.8 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value included in: ​ ​ ​ ​ ​ ​ ​ ​ ​ Accounts payable and accrued liabilities ​ $ — ​ $ 12.0 ​ $ 13.2 Other non-current liabilities ​ ​ 6.6 ​ ​ — ​ ​ — Total fair value ​ $ 6.6 ​ $ 12.0 ​ $ 13.2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2018 ​ ​ Geneva ​ Perennial ​ Kapstream Fair value included in: ​ ​ ​ ​ ​ ​ ​ ​ ​ Accounts payable and accrued liabilities ​ $ — ​ $ — ​ $ 13.8 Other non-current liabilities ​ ​ 25.3 ​ ​ 9.9 ​ ​ 12.3 Total fair value ​ $ 25.3 ​ $ 9.9 ​ $ 26.1 ​ Acquisition of Geneva The consideration payable on the acquisition of Geneva in 2014 included two contingent tranches payable over six years. The fair value of the contingent consideration payable upon the acquisition of Geneva is estimated at each reporting date by forecasting revenue, as defined by the sale and purchase agreement, over the contingency period and by determining whether targets will be met. Significant unobservable inputs used in the valuation are limited to forecast revenues, which factor in expected growth in assets under management (“AUM”) based on performance and industry trends. A fair value adjustment due to a revised forecast resulted in a $20.0 million decrease to the liability during the three months ended June 30, 2019. The adjustment was recorded in other non-operating income, net on JHG’s Condensed Consolidated Statements of Comprehensive Income. The remaining change in the liability is due to the unwind of the discount. Acquisition of Perennial The acquisition of Perennial included earn-out payable in 2019. The earn-out has employee service conditions, is based on net management fee revenue and is accrued over the service period as compensation expense. The fair value of the Perennial earn-out is calculated at each reporting date by forecasting Perennial revenues over the contingency period and determining whether the forecasted amounts meet the defined targets. The significant unobservable input used in the valuation is forecasted revenue, and the liability increased $2.1 million during the six months ended June 30, 2019. Acquisition of Kapstream The purchase of Kapstream was a step acquisition and the purchase of the second step (49%) had contingent consideration of up to $43.0 million. Payment of the contingent consideration is subject to all Kapstream products and certain products advised by the Group, reaching defined revenue targets on the first, second and third anniversaries of January 31, 2017. The contingent consideration is payable in three equal installments on the anniversary dates and is indexed to the performance of the premier share class of the Kapstream Absolute Return Income Fund. When Kapstream achieves the defined revenue targets, the holders receive the value of the contingent consideration adjusted for gains or losses attributable to the mutual fund to which the contingent consideration is indexed, subject to tax withholding. On January 31, 2018 and 2019, the first and second anniversary of the acquisition, Kapstream reached defined revenue targets, and the Group paid $14.1 million in February 2019 and $15.3 million in February 2018. The fair value of the Kapstream contingent consideration is calculated at each reporting date by forecasting certain Kapstream AUM or defined revenue over the contingency period and determining whether the forecasted amounts meet the defined targets. Significant unobservable inputs used in the valuation are limited to forecasted Kapstream AUM and performance against defined revenue targets. No fair value adjustment was necessary during the three and six months ended June 30, 2019. Disposal of Volantis On April 1, 2017, the Group completed the sale of the Volantis UK Small Cap (“Volantis”) alternative team assets. Consideration for the sale was a 10% share of the management and performance fees generated by Volantis for a period of three years. The fair value of the Volantis contingent consideration is estimated at each reporting date by forecasting revenues over the contingency period of three years. Significant unobservable inputs used in the valuation are limited to forecast revenues, which factor in expected growth in AUM based on performance and industry trends. Increases in forecast revenue increase the fair value of the consideration, while decreases in forecast revenue decrease the fair value. The forecasted share of revenues is then discounted back to the valuation date using a discount rate. As of June 30, 2019, and December 31, 2018, the fair value of the Volantis contingent consideration was $3.3 million and $3.9 million, respectively. Deferred Bonuses Deferred bonuses represent liabilities to employees over the vesting period that will be settled by investments in JHG products. The significant unobservable inputs are investment designations and vesting periods. Redeemable Noncontrolling Interests in Intech Redeemable noncontrolling interests in Intech Investment Management LLC (“Intech”) are measured at fair value on a quarterly basis or more frequently if events or circumstances indicate that a material change in the fair value of Intech has occurred. The fair value of Intech is determined using a valuation methodology that incorporates observable metrics from publicly traded peer companies as valuation comparables and adjustments related to investment performance and changes in AUM. Changes in fair value are recognized in other non-operating income, net on JHG’s Condensed Consolidated Statements of Comprehensive Income. Redeemable Noncontrolling Interests in Consolidated Seeded Investment Products Redeemable noncontrolling interests in consolidated seeded investment products are measured at fair value. Their fair values are primarily driven by the fair value of the investments in consolidated funds. The fair value of redeemable noncontrolling interests may also fluctuate from period to period based on changes in the Group’s relative ownership percentage of seed investments. Changes in fair value are recognized in investment gains (losses), net on JHG’s Condensed Consolidated Statements of Comprehensive Income. Changes in Fair Value Changes in fair value of JHG’s Level 3 assets for the three and six months ended June 30, 2019 and 2018, are as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ 2019 2018 2019 2018 Beginning of period fair value ​ $ 19.8 ​ $ 47.2 ​ $ 23.1 ​ $ 46.5 Settlements ​ (0.9) ​ (1.8) ​ (1.2) ​ (2.2) Movement recognized in net income ​ 0.2 ​ (6.1) ​ (2.9) ​ (5.3) Movements recognized in other comprehensive income ​ — ​ (0.6) ​ 0.1 ​ (0.3) End of period fair value ​ $ 19.1 ​ $ 38.7 ​ $ 19.1 ​ $ 38.7 ​ Changes in fair value of JHG’s individual Level 3 liabilities and redeemable noncontrolling interests for the three and six months ended June 30, 2019 and 2018, are as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended June 30, ​ ​ 2019 ​ 2018 ​ ​ ​ ​ ​ Redeemable ​ ​ ​ ​ ​ ​ ​ Redeemable ​ ​ Contingent ​ Deferred ​ noncontrolling ​ Contingent ​ Deferred ​ Dai-ichi ​ noncontrolling ​ ​ consideration ​ bonuses ​ interests ​ consideration ​ bonuses ​ option ​ interests Beginning of year fair value ​ $ 49.8 ​ $ 83.1 ​ $ 137.0 ​ $ 59.2 ​ $ 79.5 ​ $ 4.3 ​ $ 217.7 Changes in ownership ​ — ​ — ​ 18.2 ​ — ​ — ​ — ​ (32.6) Net movement in bonus deferrals ​ — ​ (22.4) ​ — ​ — ​ (15.2) ​ — ​ — Fair value adjustments ​ (20.0) ​ — ​ — ​ (0.2) ​ — ​ (1.9) ​ (0.2) Unrealized gains (losses) ​ 2.4 ​ — ​ (1.6) ​ — ​ — ​ — ​ (6.5) Amortization of Intech appreciation rights ​ — ​ — ​ 0.3 ​ — ​ — ​ — ​ 0.3 Distributions ​ — ​ — ​ (0.3) ​ — ​ — ​ — ​ (0.3) Foreign currency translation ​ (0.4) ​ — ​ — ​ (1.7) ​ — ​ (0.3) ​ (0.6) End of period fair value ​ $ 31.8 ​ $ 60.7 ​ $ 153.6 ​ $ 57.3 ​ $ 64.3 ​ $ 2.1 ​ $ 177.8 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six months ended June 30, ​ ​ 2019 ​ 2018 ​ ​ ​ ​ ​ Redeemable ​ ​ ​ ​ ​ ​ Redeemable ​ ​ Contingent ​ Deferred ​ noncontrolling ​ Contingent ​ Deferred ​ Dai-ichi ​ noncontrolling ​ ​ consideration ​ bonuses ​ interests ​ consideration ​ bonuses ​ option ​ interests Beginning of period fair value ​ $ 61.3 ​ $ 68.5 ​ $ 136.1 ​ $ 76.6 ​ $ 64.7 ​ $ 26.1 ​ $ 190.3 Changes in ownership ​ — ​ — ​ 14.2 ​ — ​ — ​ — ​ (5.5) Net movement in bonus deferrals ​ — ​ (7.8) ​ — ​ — ​ (0.4) ​ — ​ — Fair value adjustments ​ (20.0) ​ — ​ — ​ 1.8 ​ — ​ (24.7) ​ 0.2 Unrealized gains (losses) ​ 4.8 ​ — ​ 3.0 ​ — ​ — ​ — ​ (5.4) Amortization of Intech appreciation rights ​ — ​ — ​ 0.6 ​ — ​ — ​ — ​ (0.6) Distributions ​ (14.1) ​ — ​ (0.3) ​ (18.8) ​ — ​ — ​ (0.4) Foreign currency translation ​ (0.2) ​ — ​ — ​ (2.3) ​ — ​ 0.7 ​ (0.8) End of period fair value ​ $ 31.8 ​ $ 60.7 ​ $ 153.6 ​ $ 57.3 ​ $ 64.3 ​ $ 2.1 ​ $ 177.8 ​ Nonrecurring Fair Value Measurements Nonrecurring Level 3 fair value measurements include goodwill and intangible assets. The Group measures the fair value of goodwill and intangible assets on initial recognition using discounted cash flow analysis that requires assumptions regarding projected future earnings and discount rates. Because of the significance of the unobservable inputs in the fair value measurements of these assets, such measurements are classified as Level 3.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	6 Months Ended
	Jun. 30, 2019
Goodwill and Intangible Assets	Note 5 — Goodwill and Intangible Assets The following table presents movements in intangible assets and goodwill during the six months ended June 30, 2019 and 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ ​ ​ Foreign ​ ​ ​ June 30, ​ ​ 2018 ​ Amortization ​ Impairment ​ translation ​ Disposal ​ 2019 Indefinite-lived intangible assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Investment management agreements ​ $ 2,495.5 ​ $ — ​ $ (18.0) ​ $ (0.9) ​ $ — ​ $ 2,476.6 Trademarks ​ 380.8 ​ — ​ ​ — ​ ​ — ​ ​ — ​ 380.8 Definite-lived intangible assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Client relationships ​ 363.3 ​ — ​ ​ — ​ ​ (0.1) ​ ​ — ​ 363.2 Accumulated amortization ​ (116.3) ​ (14.7) ​ ​ — ​ ​ 0.1 ​ ​ — ​ (130.9) Net intangible assets ​ $ 3,123.3 ​ $ (14.7) ​ $ (18.0) ​ $ (0.9) ​ $ — ​ $ 3,089.7 Goodwill ​ $ 1,478.0 ​ $ — ​ $ — ​ $ (0.6) ​ $ — ​ $ 1,477.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ ​ Foreign ​ ​ June 30, ​ ​ 2017 ​ Amortization ​ Impairment ​ translation ​ Disposal ​ 2018 Indefinite-lived intangible assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Investment management agreements ​ $ 2,543.9 ​ $ — ​ $ — ​ $ (20.0) ​ $ — ​ $ 2,523.9 Trademarks ​ 381.2 ​ — ​ ​ — ​ ​ (0.3) ​ ​ — ​ 380.9 Definite-lived intangible assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Client relationships ​ 369.4 ​ — ​ ​ — ​ ​ (3.0) ​ ​ — ​ 366.4 Accumulated amortization ​ (89.7) ​ (14.8) ​ ​ — ​ ​ 1.3 ​ ​ — ​ (103.2) Net intangible assets ​ $ 3,204.8 ​ $ (14.8) ​ $ — ​ $ (22.0) ​ $ — ​ $ 3,168.0 Goodwill ​ $ 1,533.9 ​ $ — ​ $ — ​ $ (19.9) ​ $ (9.5) ​ $ 1,504.5 ​ The Group recognized an $18.0 million impairment related to certain mutual fund investment management agreements during the three months ended June 30, 2019, due to lower than expected growth. ​ Future Amortization Expected future amortization expense related to client relationships is summarized below (in millions): ​ ​ ​ ​ Future amortization Amount 2019 (remainder of year) ​ $ 14.7 2020 ​ 29.4 2021 ​ 26.5 2022 ​ 18.0 2023 ​ 17.8 Thereafter ​ 125.9 Total ​ $ 232.3 ​

Leases

Leases	6 Months Ended
	Jun. 30, 2019
Leases
Leases	Note 6 — Leases The Group’s leases include operating and finance leases for property and equipment. Property leases include office space in the United Kingdom (“UK”), Europe, the United States (“U.S.”) and the Asia-Pacific region. Equipment leases include copiers and server equipment located throughout JHG’s office space. The Group’s leases have remaining lease terms of one year to 10 years. Certain leases include options to extend or early terminate the leases, however, the Group currently does not intend to exercise these options and they are not reflected in the Group’s lease assets and liabilities. The impact of operating and financing leases on the Group’s financial statements is summarized below. Balance Sheet Operating and financing lease assets and liabilities on JHG’s Condensed Consolidated Balance Sheets as of June 30, 2019, consisted of the following (in millions): ​ ​ ​ ​ Operating lease right-of-use assets: June 30, 2019 Other non-current assets ​ $ 138.1 ​ ​ ​ Operating lease liabilities: ​ ​ ​ Accounts payable and accrued liabilities ​ $ 26.4 Other non-current liabilities ​ ​ 133.4 Total operating lease liabilities ​ $ 159.8 ​ ​ ​ ​ Finance lease right-of-use assets: ​ ​ ​ Property and equipment, cost ​ $ 13.0 Accumulated depreciation ​ ​ (11.6) Property and equipment, net ​ $ 1.4 ​ ​ ​ ​ Finance lease liabilities ​ ​ ​ Accounts payable and accrued liabilities ​ $ 0.9 Other non-current liabilities ​ ​ 0.6 Total finance lease liabilities ​ $ 1.5 ​ Statement of Comprehensive Income The components of lease expense on JHG’s Condensed Consolidated Statements of Comprehensive Income for the three and six months ended June 30, 2019, is summarized below (in millions): ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ June 30, 2019 June 30, 2019 Operating lease cost (1) $ 8.6 ​ $ 19.5 ​ ​ ​ ​ Finance lease cost: ​ ​ ​ ​ ​ Amortization of right-of-use asset (2) $ 0.3 ​ $ 0.6 Interest on lease liabilities (3) ​ — ​ ​ — Total finance lease cost $ 0.3 ​ $ 0.6 ​ (1) Included in general, administrative and occupancy on the Group’s Condensed Consolidated Statements of Comprehensive Income. (2) Included in depreciation and amortization on the Group’s Condensed Consolidated Statements of Comprehensive Income. (3) Included in interest expense on the Group’s Condensed Consolidated Statements of Comprehensive Income. ​ The Group subleases certain office buildings in the UK and received $1.9 million and $3.6 million from the tenants during the three and six months ended June 30, 2019, respectively. The Group recognized a $4.7 million impairment of a subleased ROU operating asset in the UK during the six months ended June 30, 2019, as collection of rents under the sublease are uncertain. Also, the Group recognized a $0.5 million impairment of a U.S. operating lease during the three months ended June 30, 2019, due to early termination of the lease. ​ Cash Flow Statement Cash payments for operating and finance leases included in the Group’s Condensed Consolidated Statements of Cash Flows for the six months ended June 30, 2019, consisted of the following (in millions): ​ ​ ​ ​ Six months ended ​ June 30, 2019 Operating cash flows from operating leases $ 17.4 Operating cash flows from finance leases $ — Financing cash flows from finance leases $ 0.6 ​ Non-cash lease transactions during the six months ended June 30, 2019, included a $19.8 million ROU asset and corresponding lease liability for a UK property lease commenced in March 2019. Supplemental Information As of June 30, 2019, the Group has an additional operating lease for office space in the U.S. that has not yet commenced. The lease will commence on September 1, 2019, with a lease term of 11 years. The future rent obligations associated with the lease are $8.4 million. The weighted-average remaining lease term, weighted-average discount rate and future lease maturities are summarized below. ​ ​ ​ ​ ​ Weighted-average remaining lease term (in months): June 30, 2019 Operating leases ​ ​ 85 Finance leases ​ ​ 19 ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average discount rate: ​ June 30, 2019 Operating leases ​ ​ 4.5% Finance leases ​ ​ 2.7% ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Future lease obligations (in millions) Operating leases ​ ​ Finance leases 2019 (excluding six months ended June 30, 2019) ​ $ 16.1 ​ $ 0.6 2020 ​ ​ 30.5 ​ ​ 0.7 2021 ​ ​ 28.2 ​ ​ 0.1 2022 ​ ​ 24.1 ​ ​ 0.1 2023 ​ ​ 22.2 ​ ​ — Thereafter ​ ​ 68.2 ​ ​ — Total lease payments ​ ​ 189.3 ​ ​ 1.5 Less interest ​ ​ 29.5 ​ ​ — Total ​ $ 159.8 ​ $ 1.5 ​ ​ ​

Debt

Debt	6 Months Ended
	Jun. 30, 2019
Debt	Note 7 — Debt Debt as of June 30, 2019, and December 31, 2018, consisted of the following (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2019 ​ December 31, 2018 ​ ​ Carrying Fair Carrying Fair ​ ​ value ​ value ​ value ​ value 4.875% Senior Notes due 2025 ​ $ 317.7 ​ $ 324.3 ​ $ 319.1 ​ $ 301.4 ​ ​ 4.875% Senior Notes Due 2025 The Group’s 4.875% Senior Notes due 2025 (“2025 Senior Notes”) have a principal value of $300.0 million as of June 30, 2019, pay interest at 4.875% semiannually on February 1 and August 1 of each year, and mature on August 1, 2025. The 2025 Senior Notes include unamortized debt premium, net at June 30, 2019, of $17.7 million, which will be amortized over the remaining life of the notes. The unamortized debt premium is recorded as a liability within long-term debt on JHG’s Condensed Consolidated Balance Sheets. JHG fully and unconditionally guarantees the obligations of Janus Capital Group Inc. (“JCG”) in relation to the 2025 Senior Notes. Credit Facility At June 30, 2019, JHG had a $200 million, unsecured, revolving credit facility (“Credit Facility”) with Bank of America Merrill Lynch International Limited as coordinator, book runner and mandated lead arranger. JHG and its subsidiaries can use the Credit Facility for general corporate purposes. The rate of interest for each interest period is the aggregate of the applicable margin, which is based on JHG’s long-term credit rating and the London Interbank Offered Rate (“LIBOR”); the Euro Interbank Offered Rate (“EURIBOR”) in relation to any loan in euros (“EUR”); or in relation to any loan in Australian dollars (“AUD”), the benchmark rate for that currency. JHG is required to pay a quarterly commitment fee on any unused portion of the Credit Facility, which is also based on JHG’s long-term credit rating. Under the Credit Facility, the financing leverage ratio cannot exceed 3.00x EBITDA. At June 30, 2019, JHG was in compliance with all covenants, and there were no borrowings under the Credit Facility at June 30, 2019, or during the six months ended June 30, 2019. The maturity date of the Credit Facility is February 16, 2024.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2019
Income Taxes	Note 8 — Income Taxes The Group’s effective tax rates for the three and six months ended June 30, 2019 and 2018, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ ​ June 30, ​ June 30, ​ ​ 2019 2018 2019 2018 ​ Effective tax rate ​ 24.0 % 22.6 % 23.5 % 22.6 % ​ The increase in the effective tax rate for the three and six months ended June 30, 2019, compared to the same periods in 2018 was primarily due to an increase in non-deductible compensation-related expenses. As of June 30, 2019, and December 31, 2018, JHG had $12.1 million and $12.4 million of unrecognized tax benefits held for uncertain tax positions, respectively. JHG estimates that the existing liability for uncertain tax positions could decrease by up to $1.1 million within the next 12 months, without giving effect to changes in foreign currency translation.

Noncontrolling Interests

Noncontrolling Interests	6 Months Ended
	Jun. 30, 2019
Noncontrolling Interests	Note 9 — Noncontrolling Interests Redeemable Noncontrolling Interests Redeemable noncontrolling interests as of June 30, 2019, and December 31, 2018, consisted of the following (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, ​ December 31, ​ 2019 2018 Consolidated seeded investment products ​ $ 138.8 ​ $ 121.6 Intech: ​ ​ ​ ​ ​ ​ Appreciation rights ​ ​ 11.4 ​ ​ 10.9 Founding member ownership interests ​ ​ 3.4 ​ ​ 3.6 Total redeemable noncontrolling interests ​ $ 153.6 ​ $ 136.1 ​ 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 fluctuate from period to period and are impacted by changes in JHG’s relative ownership, changes in the amount of third-party investment in seeded products and volatility in the market value of the seeded products’ underlying securities. Third-party redemption of investments is redeemed from the respective product’s net assets and cannot be redeemed from the assets of other seeded products or from the assets of JHG. The following table presents the movement in redeemable noncontrolling interests in consolidated seeded investment products for the three and six months ended June 30, 2019 and 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ 2019 2018 2019 2018 Opening balance ​ $ 122.0 ​ $ 202.9 ​ $ 121.6 ​ $ 174.9 Changes in market value ​ 2.7 ​ (6.7) ​ 7.2 ​ (5.6) Changes in ownership ​ 14.2 ​ (32.6) ​ 10.0 ​ (5.5) Foreign currency translation ​ ​ (0.1) ​ ​ (0.6) ​ ​ — ​ ​ (0.8) Closing balance ​ $ 138.8 ​ $ 163.0 ​ $ 138.8 ​ $ 163.0 ​ Intech Intech ownership interests held by a founding member had an estimated fair value of $3.4 million as of June 30, 2019, representing an approximate 1.1% ownership of Intech. This founding member is entitled to retain his remaining Intech interests until his death and has the option to require JHG to purchase his ownership interests in Intech at fair value. Intech appreciation rights are being amortized on a graded vesting method over the respective vesting period. The appreciation rights are exercisable upon termination of employment from Intech to the extent vested. Upon exercise, the appreciation rights are settled in Intech equity. Nonredeemable Noncontrolling Interests Nonredeemable noncontrolling interests as of June 30, 2019, and December 31, 2018, are as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, ​ December 31, ​ 2019 2018 Nonredeemable noncontrolling interests in: ​ ​ ​ ​ ​ ​ Seed capital investments ​ $ 9.4 ​ $ 8.3 Intech ​ 13.0 ​ 13.2 Total nonredeemable noncontrolling interests ​ $ 22.4 ​ $ 21.5 ​

Long-Term Incentive and Employe

Long-Term Incentive and Employee Compensation	6 Months Ended
	Jun. 30, 2019
Long-Term Incentive and Employee Compensation	Note 10 — Long-Term Incentive and Employee Compensation The Group granted $4.5 million and $153.9 million in long-term incentive awards during the three and six months ended June 30, 2019, respectively, which generally vest and will be recognized on a graded vesting method over a three- or four-year period.

Retirement Benefit Plans

Retirement Benefit Plans	6 Months Ended
	Jun. 30, 2019
Retirement Benefit Plans	Note 11 — Retirement Benefit Plans The Group operates defined contribution retirement benefit plans and defined benefit pension plans. The main defined benefit pension plan sponsored by the Group is the defined benefit section of the Janus Henderson Group UK Pension Scheme (“JHGPS”). Net Periodic Benefit Credit The components of net periodic benefit credit in respect of defined benefit plans for the three and six months ended June 30, 2019 and 2018, include the following (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ 2019 2018 2019 2018 Service cost ​ $ (0.3) ​ $ (0.3) ​ $ (0.6) ​ $ (0.6) Interest cost ​ (4.6) ​ (4.2) ​ (9.3) ​ (9.0) Expected return on plan assets ​ 5.2 ​ 5.4 ​ 10.6 ​ 11.5 Net periodic benefit credit ​ 0.3 ​ 0.9 ​ $ 0.7 ​ $ 1.9 ​

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	6 Months Ended
	Jun. 30, 2019
Accumulated Other Comprehensive Loss	Note 12 — Accumulated Other Comprehensive Loss Changes in accumulated other comprehensive loss, net of tax, for the three and six months ended June 30, 2019 and 2018, are as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended June 30, ​ ​ 2019 ​ 2018 ​ ​ Foreign ​ Retirement ​ ​ ​ ​ Foreign ​ Retirement ​ ​ ​ ​ currency asset, net Total currency asset, net Total Beginning balance ​ $ (411.5) ​ $ 24.7 ​ $ (386.8) ​ $ (272.4) ​ $ 21.0 ​ $ (251.4) Other comprehensive income (loss) ​ ​ (37.3) ​ ​ — ​ ​ (37.3) ​ ​ (104.7) ​ ​ — ​ ​ (104.7) Less: other comprehensive loss (income) attributable to noncontrolling interests ​ ​ 0.1 ​ ​ — ​ ​ 0.1 ​ ​ 0.6 ​ ​ — ​ ​ 0.6 Ending balance ​ $ (448.7) ​ $ 24.7 ​ $ (424.0) ​ $ (376.5) ​ $ 21.0 ​ $ (355.5) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six months ended June 30, ​ ​ 2019 ​ 2018 ​ ​ Foreign ​ Retirement benefit ​ ​ ​ ​ Foreign ​ Retirement ​ ​ ​ ​ currency asset, net Total currency asset, net Total Beginning balance ​ $ (448.2) ​ $ 24.7 ​ $ (423.5) ​ $ (325.3) ​ $ 21.0 ​ $ (304.3) Other comprehensive income ​ ​ (0.5) ​ ​ — ​ ​ (0.5) ​ ​ (52.0) ​ ​ — ​ ​ (52.0) Less: other comprehensive loss (income) attributable to noncontrolling interests ​ ​ — ​ ​ — ​ ​ — ​ ​ 0.8 ​ ​ — ​ ​ 0.8 Ending balance ​ $ (448.7) ​ $ 24.7 ​ $ (424.0) ​ $ (376.5) ​ $ 21.0 ​ $ (355.5) ​ The components of other comprehensive income, net of tax for the three and six months ended June 30, 2019 and 2018, are as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended June 30, ​ ​ 2019 ​ 2018 ​ ​ Pre-tax ​ Tax ​ ​ ​ Pre-tax ​ Tax ​ ​ ​ amount impact Net amount amount impact Net amount Foreign currency translation adjustments ​ $ (37.7) ​ $ 0.4 ​ $ (37.3) ​ $ (104.7) ​ $ — ​ $ (104.7) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six months ended June 30, ​ ​ 2019 ​ 2018 ​ ​ Pre-tax ​ Tax ​ ​ ​ Pre-tax ​ Tax ​ ​ ​ amount impact Net amount amount impact Net amount Foreign currency translation adjustments ​ $ (2.4) ​ $ 1.9 ​ $ (0.5) ​ $ (52.0) ​ $ — ​ $ (52.0) ​

Changes in Equity

Changes in Equity	6 Months Ended
	Jun. 30, 2019
Changes in Equity
Changes in Equity	Note 13 — Changes in Equity The following tables present the condensed consolidated statements of changes in equity for the three months ended June 30, 2019 and 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended June 30, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Additional ​ ​ ​ ​ ​ other ​ ​ ​ ​ ​ Nonredeemable ​ ​ ​ ​ ​ Number of ​ ​ Common ​ ​ paid-in ​ ​ Treasury ​ ​ comprehensive ​ ​ Retained ​ ​ noncontrolling ​ ​ Total ​ ​ shares ​ ​ stock ​ ​ capital ​ ​ shares ​ ​ loss ​ ​ earnings ​ ​ interests ​ ​ equity Balance at April 1, 2019 ​ 195.2 ​ $ 292.7 ​ $ 3,802.1 ​ $ (165.4) ​ $ (386.8) ​ $ 1,309.9 ​ $ 22.6 ​ $ 4,875.1 Net income ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 109.4 ​ ​ 0.2 ​ ​ 109.6 Other comprehensive loss ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (37.2) ​ — ​ ​ — ​ (37.2) Dividends paid to shareholders ​ — ​ ​ — ​ ​ 0.1 ​ ​ — ​ — ​ ​ (68.7) ​ ​ — ​ (68.6) Share buyback program ​ (3.6) ​ ​ (5.2) ​ ​ — ​ ​ — ​ ​ — ​ ​ (70.0) ​ ​ — ​ ​ (75.2) Distributions to noncontrolling interests ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (0.4) ​ ​ (0.4) Fair value adjustments to redeemable noncontrolling interests ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 0.2 ​ ​ — ​ ​ 0.2 Purchase of common stock for stock-based compensation plans — ​ — ​ ​ (1.8) ​ ​ 0.8 ​ — ​ ​ — ​ ​ — ​ (1.0) Vesting of stock-based compensation plans ​ — ​ ​ — ​ ​ (16.8) ​ ​ 16.8 ​ — ​ ​ — ​ ​ — ​ — Stock-based compensation plan expense ​ — ​ — ​ ​ 18.0 ​ ​ — ​ — ​ ​ — ​ ​ — ​ 18.0 Balance at June 30, 2019 ​ 191.6 ​ $ 287.5 ​ $ 3,801.6 ​ $ (147.8) ​ $ (424.0) ​ $ 1,280.8 ​ $ 22.4 ​ $ 4,820.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended June 30, 2018 ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Additional ​ ​ ​ ​ ​ other ​ ​ ​ ​ ​ Nonredeemable ​ ​ ​ ​ ​ Number of ​ ​ Common ​ ​ paid-in ​ ​ Treasury ​ ​ comprehensive ​ ​ Retained ​ ​ noncontrolling ​ ​ Total ​ ​ shares ​ ​ stock ​ ​ capital ​ ​ shares ​ ​ loss ​ ​ earnings ​ ​ interests ​ ​ equity Balance at April 1, 2018 ​ 200.4 ​ $ 300.6 ​ $ 3,786.0 ​ $ (198.9) ​ $ (251.4) ​ $ 1,255.9 ​ $ 34.7 ​ $ 4,926.9 Net income ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 140.6 ​ ​ (3.4) ​ ​ 137.2 Other comprehensive loss ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (104.1) ​ — ​ ​ — ​ (104.1) Dividends paid to shareholders ​ — ​ ​ — ​ ​ 0.1 ​ ​ — ​ — ​ ​ (71.7) ​ ​ — ​ (71.6) Distributions to noncontrolling interests ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (3.0) ​ ​ (3.0) Fair value adjustments to redeemable noncontrolling interests ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 0.1 ​ ​ — ​ ​ 0.1 Redemptions of convertible debt ​ — ​ ​ — ​ ​ (0.1) ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (0.1) Purchase of common stock for stock-based compensation plans — ​ — ​ ​ (0.2) ​ ​ (1.2) ​ — ​ ​ — ​ ​ — ​ (1.4) Vesting of stock-based compensation plans ​ — ​ ​ — ​ ​ (27.2) ​ ​ 27.2 ​ — ​ ​ — ​ ​ — ​ — Stock-based compensation plan expense ​ — ​ — ​ ​ 24.8 ​ ​ — ​ — ​ ​ — ​ ​ — ​ 24.8 Proceeds from stock-based compensation plans ​ — ​ ​ — ​ ​ 0.1 ​ ​ — ​ — ​ ​ — ​ ​ — ​ 0.1 Balance at June 30, 2018 ​ 200.4 ​ $ 300.6 ​ $ 3,783.5 ​ $ (172.9) ​ $ (355.5) ​ $ 1,324.9 ​ $ 28.3 ​ $ 4,908.9 ​

Earnings and Dividends Per Shar

Earnings and Dividends Per Share	6 Months Ended
	Jun. 30, 2019
Earnings and Dividends Per Share	​ Note 14 — Earnings and Dividends Per Share Earnings Per Share The following is a summary of the earnings per share calculation for the three and six months ended June 30, 2019 and 2018 (in millions, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ 2019 2018 2019 2018 Net income attributable to JHG ​ $ 109.4 ​ $ 140.6 ​ $ 203.5 ​ $ 305.8 Less: allocation of earnings to participating stock-based awards ​ ​ (3.2) ​ ​ (3.8) ​ ​ (5.6) ​ ​ (7.6) Net income attributable to JHG common shareholders ​ $ 106.2 ​ $ 136.8 ​ $ 197.9 ​ $ 298.2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average common shares outstanding — basic ​ 190.2 ​ 195.8 ​ 191.1 ​ 195.9 Dilutive effect of non -participating stock-based awards ​ ​ 0.5 ​ ​ 0.8 ​ ​ 0.5 ​ ​ 1.3 Weighted-average common shares outstanding — diluted ​ 190.7 ​ 196.6 ​ 191.6 ​ 197.2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ $ 0.56 ​ $ 0.70 ​ $ 1.04 ​ $ 1.52 Diluted (two class) ​ $ 0.56 ​ $ 0.70 ​ $ 1.03 ​ $ 1.51 ​ The following instruments are anti-dilutive and have not been included in the weighted-average diluted shares outstanding calculation (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ 2019 2018 2019 2018 Unvested nonparticipating stock awards 1.0 0.6 1.0 0.6 Dai-ichi options — 10.0 — 10.0 ​ The Dai-ichi options expired on October 3, 2018. Dividends Per Share The payment of cash dividends is within the discretion of JHG’s Board of Directors and depends on many factors, including, but not limited to, the Group’s results of operations, financial condition, capital requirements, and general business conditions and legal requirements. The following is a summary of cash dividends paid during the three and six months ended June 30, 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ Dividend ​ Date ​ Dividends paid ​ Date per share declared ​ (in US$ millions) paid $ 0.36 ​ February 4, 2019 $ 69.7 ​ February 26, 2019 $ 0.36 ​ May 1, 2019 ​ $ 68.6 ​ May 29, 2019 ​ On July 30, 2019, JHG’s Board of Directors declared a cash dividend of $0.36 per share. The quarterly dividend will be paid on August 28, 2019, to shareholders of record at the close of business on August 12, 2019.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2019
Commitments and Contingencies	​ ​ Note 15 — Commitments and Contingencies Commitments and contingencies may arise in the normal course of business. Refer to Note 6 — Leases for information related to operating and financing lease commitments. As of June 30, 2019, there were no other material changes in the commitments and contingencies as reported in JHG’s Annual Report on Form 10-K for the year ended December 31, 2018. Litigation and Other Regulatory Matters JHG is periodically involved in various legal proceedings and other regulatory matters. Richard Pease v. Henderson Administration Limited ​ The outcome of a court case involving an ex-employee was determined in the first quarter of 2018. The case related to the fees the Group should receive after a fund was transferred to an ex-employee (the “Fund Transfer Fees”) and the ex-employee’s entitlement to deferred and forfeited remuneration. The judgment given in the case resulted in the Group recognizing a $12.2 million charge in general, administrative and occupancy on JHG’s Condensed Consolidated Statements of Comprehensive Income after the judge held that the ex-employee was not bound to pay the Fund Transfer Fees and that the ex-employee’s contract gave him an entitlement to deferred and forfeited remuneration. The amount also includes legal costs relating to the case. Henderson Administration Limited (“HAL”), a wholly owned subsidiary of JHG, appealed the part of the judgment relating to the Fund Transfer Fees and judgment was handed down by the Court of Appeal of England and Wales on February 15, 2019, in favor of HAL. As a result, and subject to any further appeal, the Group was awarded the Fund Transfer Fees and related interest of approximately $5.0 million and $0.3 million, respectively. It will also be entitled to certain costs relating to the appeal and the earlier trial insofar as they relate to the Fund Transfer Fees claim. ​ Eisenberg v. Credit Suisse AG and Janus Indices, Halbert v. Credit Suisse AG and Janus Indices, Qiu v. Credit Suisse AG and Janus Indices and Y-GAR Capital v. Credit Suisse AG and Janus Indices, and Rubinstein v. Credit Suisse Group AG and Janus Indices ​ On March 15, 2018, a class action lawsuit was filed in the United States District Court for the Southern District of New York (“SDNY”) against Janus Index & Calculation Services LLC, which effective January 1, 2019, was renamed Janus Henderson Indices LLC (“Janus Indices”), a subsidiary of the Group, on behalf of a class consisting of investors who purchased VelocityShares Daily Inverse VIX Short-Term ETN (Ticker: XIV) between January 29, 2018, and February 5, 2018 ( Eisenberg v. Credit Suisse AG and Janus Indices Halbert v. Credit Suisse AG and Janus Indices Qiu v. Credit Suisse AG and Janus Indices Halbert Qiu Eisenberg Eisenberg Qiu Set Capital LLC, et al. v. Credit Suisse AG, et al. ​ On February 7, 2019, a fourth lawsuit was filed against Janus Indices, Janus Distributors LLC, Janus Henderson Group plc, and Credit Suisse in the United States District Court of the Eastern District of New York (“EDNY”) by certain investors in XIV ( Y-GAR Capital LLC v. Credit Suisse Group AG, et al.) Y-GAR ​ ​ On February 4, 2019, a fifth lawsuit was filed against Janus Index, Janus Distributors LLC, Janus Henderson Group plc and various Credit Suisse persons in the SDNY ( Rubinstein v. Credit Suisse Group AG, et al.) ​ The Group believes the claims in these exchange-traded note lawsuits are without merit and is strongly defending the actions. As of June 30, 2019, the Group cannot reasonably estimate possible losses from the claims in the exchange-traded note lawsuits. ​

Basis of Presentation and Sig_2

Basis of Presentation and Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2019
Basis of Presentation	Basis of Presentation In the opinion of management of Janus Henderson Group plc (“JHG” or “the Group”), the accompanying unaudited condensed consolidated financial statements contain all normal recurring adjustments necessary to fairly state the financial position, results of operations and cash flows of JHG 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-Q pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. These financial statements should be read in conjunction with the annual consolidated financial statements and notes presented in JHG’s Annual Report on Form 10-K for the year ended December 31, 2018. The December 31, 2018, condensed balance sheet data was derived from audited financial statements, but does not include all disclosures required by GAAP. Events subsequent to the balance sheet date have been evaluated for inclusion in the accompanying financial statements through the issuance date and are included in the notes to the condensed consolidated financial statements. Certain prior year amounts in JHG’s Condensed Consolidated Statements of Comprehensive Income have been reclassified to conform to current year presentation. Specifically, revenue amounts related to certain transfer agent and administrative activities performed for investment products that were previously classified in other revenue were reclassified to shareowner servicing fees. There is no change to consolidated total revenue, operating income, net income or cash flows as a result of this change in classification.
Recent Accounting Pronouncements Adopted	Recent Accounting Pronouncements Adopted Leases In February 2016, the Financial Accounting Standards Board (“FASB”) issued a new standard on accounting for leases. The new standard represents a significant change to lease accounting and introduces a lessee model that brings leases onto the balance sheet. The standard also aligns certain underlying principles of the new lessor model with those in the FASB’s new revenue recognition standard. Furthermore, the new standard addresses other concerns related to the prior leases model. The standard became effective January 1, 2019. The Group adopted the new standard effective January 1, 2019, using the modified retrospective approach. Comparative prior periods were not adjusted upon adoption, as the Group utilized the practical expedients available under the guidance. Specifically, the Group did not (i) reassess existing contracts for embedded leases, (ii) reassess existing lease agreements for finance or operating classification, or (iii) reassess existing lease agreements in consideration of initial direct costs. Upon adoption, the Group recognized $129.8 million in right-of-use (“ROU”) assets related to its leased property and equipment. Corresponding lease liabilities of $146.4 million were also recognized. The Group’s property leases represent the vast majority of its ROU assets and lease liabilities, with office spaces in Denver and London representing a significant portion of its leased property. The Group’s leases policy follows. Refer to further disclosure in Note 6. Leases Policy — Updated January 1, 2019 The Group determines if an arrangement is a lease at inception. Operating lease ROU assets are included in other non-current assets in the Group’s Condensed Consolidated Balance Sheets. The current and non-current portions of operating lease liabilities are included in accounts payable and accrued liabilities and in other non-current liabilities, respectively. Finance lease ROU assets are included in property, equipment and software, net, and finance lease liabilities are included in other non-current liabilities. ROU assets represent the Group’s right to use an underlying asset for the lease term, and lease liabilities represent the Group’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As most of JHG’s leases do not provide an implicit rate, the Group uses its incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The operating lease ROU asset also includes any lease payments made and excludes lease incentives. The Group’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. Lease expense for lease payments is recognized on a straight-line basis over the lease term. Hedge Accounting In August 2017, the FASB issued an updated standard that amended hedge accounting. The standard expanded the strategies eligible for hedge accounting, changed how companies assess hedge effectiveness and required new disclosures and presentation. The Group adopted the standard effective January 1, 2019. The adoption did not have a material impact on the Group’s results of operations or financial position.
Recent Accounting Pronouncements Not Yet Adopted	Recent Accounting Pronouncements Not Yet Adopted Retirement Benefit Plans In August 2018, the FASB issued an accounting standards update (“ASU”) that modifies the disclosure requirements for employers that sponsor defined benefit pension plans. The ASU removes, adds and clarifies a number of disclosure requirements related to sponsored benefit plans. The standard is effective January 1, 2021, for calendar year-end companies, and early adoption is permitted. The Group is evaluating the effect of adopting this new accounting standard. Implementation Costs — Cloud Computing Arrangements In August 2018, the FASB issued an ASU that aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement with the requirements for implementation costs incurred to develop or obtain internal-use software. The ASU is effective January 1, 2020, for calendar year-end companies and for the interim periods within those years. Early adoption is permitted. The ASU allows either a retrospective or prospective approach to all implementation costs incurred after adoption. The Group is evaluating the effect of adopting this new accounting standard.

Consolidation (Tables)

Consolidation (Tables)	6 Months Ended
	Jun. 30, 2019
Schedule of consolidated voting right entities (VREs)	The following table presents the balances related to consolidated voting rights entities (“VREs”) that were recorded on JHG’s Condensed Consolidated Balance Sheets, including JHG’s net interest in these products (in millions): ​ ​ ​ ​ ​ ​ ​ ​ June 30, December 31, ​ ​ 2019 ​ 2018 Investment securities ​ $ 9.3 ​ $ 13.9 Cash and cash equivalents ​ ​ 0.1 ​ 1.4 Other current assets ​ ​ 0.2 ​ ​ 0.1 Accounts payable and accrued liabilities ​ ​ (0.1) ​ ​ (0.1) Total ​ ​ 9.5 ​ 15.3 Redeemable noncontrolling interests in consolidated VREs ​ ​ (4.3) ​ (6.0) JHG's net interest in consolidated VREs ​ $ 5.2 ​ $ 9.3 ​

Investment Securities (Tables)

Investment Securities (Tables)	6 Months Ended
	Jun. 30, 2019
Summary of investment securities	JHG’s investment securities as of June 30, 2019, and December 31, 2018, are summarized as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, ​ December 31, ​ 2019 2018 Seeded investment products: ​ ​ ​ ​ ​ ​ Consolidated VIEs ​ $ 311.1 ​ $ 282.7 Consolidated VREs ​ ​ 9.3 ​ ​ 13.9 Unconsolidated VIEs and VREs ​ ​ 32.1 ​ ​ 53.8 Separate accounts ​ ​ 56.7 ​ ​ 71.6 Pooled investment funds ​ ​ 10.6 ​ ​ 25.5 Total seeded investment products ​ 419.8 ​ 447.5 Investments related to deferred compensation plans ​ 132.6 ​ 120.3 Other investments ​ ​ 5.5 ​ ​ 6.7 Total investment securities ​ $ 557.9 ​ $ 574.5 ​
Schedule of net unrealized gains (losses) on trading securities	Trading Securities Net unrealized gains (losses) on investment securities held as of June 30, 2019 and 2018, are summarized as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ 2019 2018 2019 2018 Unrealized gains (losses) on investment securities held at period end $ 4.6 $ (13.6) $ 15.7 $ (21.5) ​
Schedule of net foreign currency translation gains (losses) on hedged seed investments denominated in foreign currencies and net gains (losses) associated with foreign currency forward contracts under net investment hedging	The Group recognized the following net foreign currency translation gains and losses on hedged seed investments denominated in currencies other than the Group’s functional currency and net gains and losses associated with foreign currency forward contracts under net investment hedge accounting for the three and six months ended June 30, 2019 and 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ ​ 2019 2018 2019 2018 Foreign currency translation $ (1.2) $ (3.3) $ (0.9) $ (3.8) Foreign currency forward contracts ​ 1.2 ​ 3.3 ​ 0.9 ​ 3.8 Total ​ $ — ​ $ — ​ $ — ​ $ — ​
Schedule of investment gains (losses), net in Consolidated Statements of Comprehensive Income	Investment gains (losses), net on JHG’s Condensed Consolidated Statements of Comprehensive Income included the following for the three and six months ended June 30, 2019 and 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ June 30, ​ June 30, ​ ​ 2019 2018 2019 2018 Seeded investment products and derivatives, net ​ $ 3.4 ​ $ (17.4) ​ $ 11.6 ​ $ (18.2) Other ​ 1.4 ​ 0.8 ​ 6.5 ​ 0.9 Investment gains (losses), net ​ $ 4.8 ​ $ (16.6) ​ $ 18.1 ​ $ (17.3) ​
Cash flows related to investment securities	Cash flows related to investment securities for the six months ended June 30, 2019 and 2018, are summarized as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six months ended June 30, ​ ​ 2019 ​ 2018 ​ ​ ​ Sales, ​ ​ Sales, ​ ​ Purchases ​ settlements ​ Purchases ​ settlements ​ ​ and ​ and ​ and ​ and ​ ​ settlements ​ maturities ​ settlements ​ maturities Investment securities ​ $ (269.1) ​ $ 246.9 ​ $ (30.9) ​ $ 58.1 ​
Not Designated as Hedging Instrument
Schedule of derivative instruments	JHG was party to the following derivative instruments as of June 30, 2019, and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ Notional Value ​ June 30, 2019 December 31, 2018 Futures ​ $ 103.5 ​ $ 147.1 Credit default swaps ​ ​ 93.0 ​ ​ 133.2 Total return swaps ​ ​ 75.8 ​ ​ 77.2 Foreign currency forward contracts ​ ​ 163.6 ​ ​ 131.8 ​
Seeded investment products
Schedule of derivative instruments	JHG’s consolidated seeded investment products were party to the following derivative instruments as of June 30, 2019, and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ Notional Value ​ June 30, 2019 December 31, 2018 Futures ​ $ 102.2 ​ $ 267.8 Contracts for differences ​ ​ 10.4 ​ ​ 8.7 Credit default swaps ​ ​ 2.4 ​ ​ 6.2 Total return swaps ​ ​ 37.8 ​ ​ 23.7 Interest rate swaps ​ 26.2 ​ 61.5 Options ​ 0.7 ​ 9.6 Swaptions ​ — ​ 8.3 Foreign currency forward contracts ​ 147.2 ​ 154.9 ​

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2019
Schedule of assets, liabilities and redeemable noncontrolling interests presented in the financial statements or disclosed in the notes to the financial statements at fair value on a recurring basis	The following table presents assets, liabilities and redeemable noncontrolling interests presented in the financial statements or disclosed in the notes to the financial statements at fair value on a recurring basis as of June 30, 2019 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value measurements using: ​ ​ ​ ​ ​ Quoted prices in ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ active markets for ​ ​ ​ ​ ​ ​ ​ ​ identical assets ​ Significant other ​ Significant ​ ​ ​ ​ ​ and liabilities ​ observable inputs ​ unobservable inputs ​ ​ ​ ​ ​ (Level 1) ​ (Level 2) ​ (Level 3) ​ Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 270.5 ​ $ — ​ $ — ​ $ 270.5 Investment securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Consolidated VIEs ​ ​ 132.9 ​ ​ 162.4 ​ ​ 15.8 ​ ​ 311.1 Other investment securities ​ ​ 185.3 ​ ​ 61.5 ​ ​ — ​ ​ 246.8 Total investment securities ​ ​ 318.2 ​ ​ 223.9 ​ ​ 15.8 ​ ​ 557.9 Seed hedge derivatives ​ ​ — ​ 2.1 ​ ​ — ​ 2.1 Volantis contingent consideration ​ — ​ — ​ 3.3 ​ 3.3 Total assets ​ $ 588.7 ​ $ 226.0 ​ $ 19.1 ​ $ 833.8 Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Derivatives in consolidated seeded investment products ​ $ — ​ $ 1.5 ​ $ — ​ $ 1.5 Seed hedge derivatives ​ ​ — ​ ​ 6.4 ​ ​ — ​ ​ 6.4 Long-term debt (1) ​ ​ — ​ ​ 324.3 ​ ​ — ​ ​ 324.3 Deferred bonuses ​ ​ — ​ ​ — ​ ​ 60.7 ​ ​ 60.7 Contingent consideration ​ ​ — ​ ​ — ​ ​ 31.8 ​ ​ 31.8 Total liabilities ​ $ — ​ $ 332.2 ​ $ 92.5 ​ $ 424.7 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Redeemable noncontrolling interests: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Consolidated seeded investment products ​ $ — ​ $ — ​ $ 138.8 ​ $ 138.8 Intech ​ ​ — ​ ​ — ​ ​ 14.8 ​ ​ 14.8 Total redeemable noncontrolling interests ​ $ — ​ $ — ​ $ 153.6 ​ $ 153.6 ​ (1) Carried at amortized cost and disclosed at fair value. ​ The following table presents assets, liabilities and redeemable noncontrolling interests presented in the financial statements or disclosed in the notes to the financial statements at fair value on a recurring basis as of December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value measurements using: ​ ​ ​ ​ ​ Quoted prices in ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ active markets for ​ ​ ​ ​ ​ ​ ​ ​ identical assets ​ Significant other ​ Significant ​ ​ ​ ​ ​ and liabilities ​ observable inputs ​ unobservable inputs ​ ​ ​ ​ ​ (Level 1) ​ (Level 2) ​ (Level 3) ​ Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 381.8 ​ $ — ​ $ — ​ $ 381.8 Investment securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Consolidated VIEs ​ ​ 103.8 ​ ​ 159.7 ​ ​ 19.2 ​ ​ 282.7 Other investment securities ​ ​ 194.5 ​ ​ 97.3 ​ ​ — ​ ​ 291.8 Total investment securities ​ 298.3 ​ 257.0 ​ 19.2 ​ 574.5 Seed hedge derivatives ​ ​ — ​ 3.2 ​ ​ — ​ 3.2 Derivatives in consolidated seeded investment products ​ ​ — ​ ​ 0.9 ​ ​ — ​ ​ 0.9 Contingent consideration ​ ​ — ​ — ​ 3.9 ​ 3.9 Total assets ​ $ 680.1 ​ $ 261.1 ​ $ 23.1 ​ $ 964.3 Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Derivatives in consolidated seeded investment products ​ $ — ​ $ 2.1 ​ $ — ​ $ 2.1 Financial liabilities in consolidated seeded investment products ​ ​ 0.4 ​ ​ — ​ ​ — ​ ​ 0.4 Seed hedge derivatives ​ ​ — ​ ​ 1.1 ​ ​ — ​ ​ 1.1 Long-term debt (1) ​ ​ — ​ ​ 301.4 ​ ​ — ​ ​ 301.4 Deferred bonuses ​ ​ — ​ ​ — ​ ​ 68.5 ​ ​ 68.5 Contingent consideration ​ ​ — ​ ​ — ​ ​ 61.3 ​ ​ 61.3 Total liabilities ​ $ 0.4 ​ $ 304.6 ​ $ 129.8 ​ $ 434.8 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Redeemable noncontrolling interests: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Consolidated seeded investment products ​ $ — ​ $ — ​ $ 121.6 ​ $ 121.6 Intech ​ ​ — ​ ​ — ​ ​ 14.5 ​ ​ 14.5 Total redeemable noncontrolling interests ​ $ — ​ $ — ​ $ 136.1 ​ $ 136.1 ​ (1) Carried at amortized cost and disclosed at fair value.
Summary of valuation techniques and significant unobservable inputs used in the valuation of the company's private equity investments	Valuation techniques and significant unobservable inputs used in the valuation of JHG’s material Level 3 assets included within consolidated VIEs as of June 30, 2019, and December 31, 2018, were as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Significant ​ ​ ​ ​ Fair ​ Valuation ​ unobservable ​ ​ As of June 30, 2019 ​ value ​ technique ​ inputs ​ Inputs Investment securities of consolidated VIEs ​ $ 15.8 Discounted Discount rate ​ 15% ​ ​ ​ ​ cash flow EBITDA multiple ​ 16.4 ​ ​ ​ ​ ​ ​ Price-earnings ratio ​ 27.7 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Significant ​ ​ ​ Fair Valuation unobservable ​ Range As of December 31, 2018 ​ value technique inputs ​ (weighted-average) Investment securities of consolidated VIEs ​ $ 19.2 Discounted Discount rate ​ 15% ​ ​ ​ ​ cash flow EBITDA multiple ​ 18.5 ​ ​ ​ ​ ​ ​ Price-earnings ratio ​ 28.4 ​
Schedule of maximum amount payable and fair value of Geneva, Perennial, Kapstream and VelocityShares contingent consideration	The maximum amount payable and fair value of Geneva Capital Management LLC (“Geneva”), Perennial Fixed Interest Partners Pty Ltd and Perennial Growth Management Pty Ltd (together “Perennial”) and Kapstream Capital Pty Limited (“Kapstream”) contingent consideration are summarized below (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of June 30, 2019 ​ ​ Geneva ​ Perennial ​ Kapstream Maximum amount payable ​ $ 61.3 ​ $ 15.8 ​ $ 13.8 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value included in: ​ ​ ​ ​ ​ ​ ​ ​ ​ Accounts payable and accrued liabilities ​ $ — ​ $ 12.0 ​ $ 13.2 Other non-current liabilities ​ ​ 6.6 ​ ​ — ​ ​ — Total fair value ​ $ 6.6 ​ $ 12.0 ​ $ 13.2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2018 ​ ​ Geneva ​ Perennial ​ Kapstream Fair value included in: ​ ​ ​ ​ ​ ​ ​ ​ ​ Accounts payable and accrued liabilities ​ $ — ​ $ — ​ $ 13.8 Other non-current liabilities ​ ​ 25.3 ​ ​ 9.9 ​ ​ 12.3 Total fair value ​ $ 25.3 ​ $ 9.9 ​ $ 26.1 ​
Schedule of changes in fair value of the recurring Level 3 fair value measurements for collective items	Changes in fair value of JHG’s Level 3 assets for the three and six months ended June 30, 2019 and 2018, are as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ 2019 2018 2019 2018 Beginning of period fair value ​ $ 19.8 ​ $ 47.2 ​ $ 23.1 ​ $ 46.5 Settlements ​ (0.9) ​ (1.8) ​ (1.2) ​ (2.2) Movement recognized in net income ​ 0.2 ​ (6.1) ​ (2.9) ​ (5.3) Movements recognized in other comprehensive income ​ — ​ (0.6) ​ 0.1 ​ (0.3) End of period fair value ​ $ 19.1 ​ $ 38.7 ​ $ 19.1 ​ $ 38.7 ​
Schedule of changes in fair value of the recurring Level 3 fair value measurements for individual items	Changes in fair value of JHG’s individual Level 3 liabilities and redeemable noncontrolling interests for the three and six months ended June 30, 2019 and 2018, are as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended June 30, ​ ​ 2019 ​ 2018 ​ ​ ​ ​ ​ Redeemable ​ ​ ​ ​ ​ ​ ​ Redeemable ​ ​ Contingent ​ Deferred ​ noncontrolling ​ Contingent ​ Deferred ​ Dai-ichi ​ noncontrolling ​ ​ consideration ​ bonuses ​ interests ​ consideration ​ bonuses ​ option ​ interests Beginning of year fair value ​ $ 49.8 ​ $ 83.1 ​ $ 137.0 ​ $ 59.2 ​ $ 79.5 ​ $ 4.3 ​ $ 217.7 Changes in ownership ​ — ​ — ​ 18.2 ​ — ​ — ​ — ​ (32.6) Net movement in bonus deferrals ​ — ​ (22.4) ​ — ​ — ​ (15.2) ​ — ​ — Fair value adjustments ​ (20.0) ​ — ​ — ​ (0.2) ​ — ​ (1.9) ​ (0.2) Unrealized gains (losses) ​ 2.4 ​ — ​ (1.6) ​ — ​ — ​ — ​ (6.5) Amortization of Intech appreciation rights ​ — ​ — ​ 0.3 ​ — ​ — ​ — ​ 0.3 Distributions ​ — ​ — ​ (0.3) ​ — ​ — ​ — ​ (0.3) Foreign currency translation ​ (0.4) ​ — ​ — ​ (1.7) ​ — ​ (0.3) ​ (0.6) End of period fair value ​ $ 31.8 ​ $ 60.7 ​ $ 153.6 ​ $ 57.3 ​ $ 64.3 ​ $ 2.1 ​ $ 177.8 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six months ended June 30, ​ ​ 2019 ​ 2018 ​ ​ ​ ​ ​ Redeemable ​ ​ ​ ​ ​ ​ Redeemable ​ ​ Contingent ​ Deferred ​ noncontrolling ​ Contingent ​ Deferred ​ Dai-ichi ​ noncontrolling ​ ​ consideration ​ bonuses ​ interests ​ consideration ​ bonuses ​ option ​ interests Beginning of period fair value ​ $ 61.3 ​ $ 68.5 ​ $ 136.1 ​ $ 76.6 ​ $ 64.7 ​ $ 26.1 ​ $ 190.3 Changes in ownership ​ — ​ — ​ 14.2 ​ — ​ — ​ — ​ (5.5) Net movement in bonus deferrals ​ — ​ (7.8) ​ — ​ — ​ (0.4) ​ — ​ — Fair value adjustments ​ (20.0) ​ — ​ — ​ 1.8 ​ — ​ (24.7) ​ 0.2 Unrealized gains (losses) ​ 4.8 ​ — ​ 3.0 ​ — ​ — ​ — ​ (5.4) Amortization of Intech appreciation rights ​ — ​ — ​ 0.6 ​ — ​ — ​ — ​ (0.6) Distributions ​ (14.1) ​ — ​ (0.3) ​ (18.8) ​ — ​ — ​ (0.4) Foreign currency translation ​ (0.2) ​ — ​ — ​ (2.3) ​ — ​ 0.7 ​ (0.8) End of period fair value ​ $ 31.8 ​ $ 60.7 ​ $ 153.6 ​ $ 57.3 ​ $ 64.3 ​ $ 2.1 ​ $ 177.8 ​

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2019
Goodwill and Intangible Assets
Summary of goodwill and intangible assets	The following table presents movements in intangible assets and goodwill during the six months ended June 30, 2019 and 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ ​ ​ Foreign ​ ​ ​ June 30, ​ ​ 2018 ​ Amortization ​ Impairment ​ translation ​ Disposal ​ 2019 Indefinite-lived intangible assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Investment management agreements ​ $ 2,495.5 ​ $ — ​ $ (18.0) ​ $ (0.9) ​ $ — ​ $ 2,476.6 Trademarks ​ 380.8 ​ — ​ ​ — ​ ​ — ​ ​ — ​ 380.8 Definite-lived intangible assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Client relationships ​ 363.3 ​ — ​ ​ — ​ ​ (0.1) ​ ​ — ​ 363.2 Accumulated amortization ​ (116.3) ​ (14.7) ​ ​ — ​ ​ 0.1 ​ ​ — ​ (130.9) Net intangible assets ​ $ 3,123.3 ​ $ (14.7) ​ $ (18.0) ​ $ (0.9) ​ $ — ​ $ 3,089.7 Goodwill ​ $ 1,478.0 ​ $ — ​ $ — ​ $ (0.6) ​ $ — ​ $ 1,477.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ ​ Foreign ​ ​ June 30, ​ ​ 2017 ​ Amortization ​ Impairment ​ translation ​ Disposal ​ 2018 Indefinite-lived intangible assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Investment management agreements ​ $ 2,543.9 ​ $ — ​ $ — ​ $ (20.0) ​ $ — ​ $ 2,523.9 Trademarks ​ 381.2 ​ — ​ ​ — ​ ​ (0.3) ​ ​ — ​ 380.9 Definite-lived intangible assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Client relationships ​ 369.4 ​ — ​ ​ — ​ ​ (3.0) ​ ​ — ​ 366.4 Accumulated amortization ​ (89.7) ​ (14.8) ​ ​ — ​ ​ 1.3 ​ ​ — ​ (103.2) Net intangible assets ​ $ 3,204.8 ​ $ (14.8) ​ $ — ​ $ (22.0) ​ $ — ​ $ 3,168.0 Goodwill ​ $ 1,533.9 ​ $ — ​ $ — ​ $ (19.9) ​ $ (9.5) ​ $ 1,504.5 ​
Client relationships
Goodwill and Intangible Assets
Schedule of expected future amortization	Expected future amortization expense related to client relationships is summarized below (in millions): ​ ​ ​ ​ Future amortization Amount 2019 (remainder of year) ​ $ 14.7 2020 ​ 29.4 2021 ​ 26.5 2022 ​ 18.0 2023 ​ 17.8 Thereafter ​ 125.9 Total ​ $ 232.3 ​

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2019
Leases
Schedule of operating and financing lease assets and liabilities	Operating and financing lease assets and liabilities on JHG’s Condensed Consolidated Balance Sheets as of June 30, 2019, consisted of the following (in millions): ​ ​ ​ ​ Operating lease right-of-use assets: June 30, 2019 Other non-current assets ​ $ 138.1 ​ ​ ​ Operating lease liabilities: ​ ​ ​ Accounts payable and accrued liabilities ​ $ 26.4 Other non-current liabilities ​ ​ 133.4 Total operating lease liabilities ​ $ 159.8 ​ ​ ​ ​ Finance lease right-of-use assets: ​ ​ ​ Property and equipment, cost ​ $ 13.0 Accumulated depreciation ​ ​ (11.6) Property and equipment, net ​ $ 1.4 ​ ​ ​ ​ Finance lease liabilities ​ ​ ​ Accounts payable and accrued liabilities ​ $ 0.9 Other non-current liabilities ​ ​ 0.6 Total finance lease liabilities ​ $ 1.5
Schedule of components of lease expense	The components of lease expense on JHG’s Condensed Consolidated Statements of Comprehensive Income for the three and six months ended June 30, 2019, is summarized below (in millions): ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ June 30, 2019 June 30, 2019 Operating lease cost (1) $ 8.6 ​ $ 19.5 ​ ​ ​ ​ Finance lease cost: ​ ​ ​ ​ ​ Amortization of right-of-use asset (2) $ 0.3 ​ $ 0.6 Interest on lease liabilities (3) ​ — ​ ​ — Total finance lease cost $ 0.3 ​ $ 0.6 ​ (1) Included in general, administrative and occupancy on the Group’s Condensed Consolidated Statements of Comprehensive Income. (2) Included in depreciation and amortization on the Group’s Condensed Consolidated Statements of Comprehensive Income. (3) Included in interest expense on the Group’s Condensed Consolidated Statements of Comprehensive Income. ​
Schedule of cash flow statement	Cash payments for operating and finance leases included in the Group’s Condensed Consolidated Statements of Cash Flows for the six months ended June 30, 2019, consisted of the following (in millions): ​ ​ ​ ​ Six months ended ​ June 30, 2019 Operating cash flows from operating leases $ 17.4 Operating cash flows from finance leases $ — Financing cash flows from finance leases $ 0.6
Schedule of supplemental information	​ ​ ​ ​ ​ Weighted-average remaining lease term (in months): June 30, 2019 Operating leases ​ ​ 85 Finance leases ​ ​ 19 ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average discount rate: ​ June 30, 2019 Operating leases ​ ​ 4.5% Finance leases ​ ​ 2.7% ​ ​ ​ ​
Schedule of future minimum payments under noncancelable operating leases	​ ​ ​ ​ ​ ​ ​ ​ Future lease obligations (in millions) Operating leases ​ ​ Finance leases 2019 (excluding six months ended June 30, 2019) ​ $ 16.1 ​ $ 0.6 2020 ​ ​ 30.5 ​ ​ 0.7 2021 ​ ​ 28.2 ​ ​ 0.1 2022 ​ ​ 24.1 ​ ​ 0.1 2023 ​ ​ 22.2 ​ ​ — Thereafter ​ ​ 68.2 ​ ​ — Total lease payments ​ ​ 189.3 ​ ​ 1.5 Less interest ​ ​ 29.5 ​ ​ — Total ​ $ 159.8 ​ $ 1.5 ​ ​
Schedule of future minimum payments under noncancelable finance leases	​ ​ ​ ​ ​ ​ ​ ​ Future lease obligations (in millions) Operating leases ​ ​ Finance leases 2019 (excluding six months ended June 30, 2019) ​ $ 16.1 ​ $ 0.6 2020 ​ ​ 30.5 ​ ​ 0.7 2021 ​ ​ 28.2 ​ ​ 0.1 2022 ​ ​ 24.1 ​ ​ 0.1 2023 ​ ​ 22.2 ​ ​ — Thereafter ​ ​ 68.2 ​ ​ — Total lease payments ​ ​ 189.3 ​ ​ 1.5 Less interest ​ ​ 29.5 ​ ​ — Total ​ $ 159.8 ​ $ 1.5

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2019
Components of debt	Debt as of June 30, 2019, and December 31, 2018, consisted of the following (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2019 ​ December 31, 2018 ​ ​ Carrying Fair Carrying Fair ​ ​ value ​ value ​ value ​ value 4.875% Senior Notes due 2025 ​ $ 317.7 ​ $ 324.3 ​ $ 319.1 ​ $ 301.4 ​ ​

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2019
Schedule of effective income tax rates	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ ​ June 30, ​ June 30, ​ ​ 2019 2018 2019 2018 ​ Effective tax rate ​ 24.0 % 22.6 % 23.5 % 22.6 % ​

Noncontrolling Interests (Table

Noncontrolling Interests (Tables)	6 Months Ended
	Jun. 30, 2019
Summary of redeemable noncontrolling interests	Redeemable noncontrolling interests as of June 30, 2019, and December 31, 2018, consisted of the following (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, ​ December 31, ​ 2019 2018 Consolidated seeded investment products ​ $ 138.8 ​ $ 121.6 Intech: ​ ​ ​ ​ ​ ​ Appreciation rights ​ ​ 11.4 ​ ​ 10.9 Founding member ownership interests ​ ​ 3.4 ​ ​ 3.6 Total redeemable noncontrolling interests ​ $ 153.6 ​ $ 136.1 ​
Schedule of movement in redeemable noncontrolling interests in consolidated seeded investment products	The following table presents the movement in redeemable noncontrolling interests in consolidated seeded investment products for the three and six months ended June 30, 2019 and 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ 2019 2018 2019 2018 Opening balance ​ $ 122.0 ​ $ 202.9 ​ $ 121.6 ​ $ 174.9 Changes in market value ​ 2.7 ​ (6.7) ​ 7.2 ​ (5.6) Changes in ownership ​ 14.2 ​ (32.6) ​ 10.0 ​ (5.5) Foreign currency translation ​ ​ (0.1) ​ ​ (0.6) ​ ​ — ​ ​ (0.8) Closing balance ​ $ 138.8 ​ $ 163.0 ​ $ 138.8 ​ $ 163.0 ​
Summary of nonredeemable noncontrolling interests	Nonredeemable noncontrolling interests as of June 30, 2019, and December 31, 2018, are as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, ​ December 31, ​ 2019 2018 Nonredeemable noncontrolling interests in: ​ ​ ​ ​ ​ ​ Seed capital investments ​ $ 9.4 ​ $ 8.3 Intech ​ 13.0 ​ 13.2 Total nonredeemable noncontrolling interests ​ $ 22.4 ​ $ 21.5 ​

Retirement Benefit Plans (Table

Retirement Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2019
Schedule of components of net periodic benefit credit	The components of net periodic benefit credit in respect of defined benefit plans for the three and six months ended June 30, 2019 and 2018, include the following (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ 2019 2018 2019 2018 Service cost ​ $ (0.3) ​ $ (0.3) ​ $ (0.6) ​ $ (0.6) Interest cost ​ (4.6) ​ (4.2) ​ (9.3) ​ (9.0) Expected return on plan assets ​ 5.2 ​ 5.4 ​ 10.6 ​ 11.5 Net periodic benefit credit ​ 0.3 ​ 0.9 ​ $ 0.7 ​ $ 1.9 ​

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	6 Months Ended
	Jun. 30, 2019
Schedule of the changes in accumulated other comprehensive loss, net of tax	Changes in accumulated other comprehensive loss, net of tax, for the three and six months ended June 30, 2019 and 2018, are as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended June 30, ​ ​ 2019 ​ 2018 ​ ​ Foreign ​ Retirement ​ ​ ​ ​ Foreign ​ Retirement ​ ​ ​ ​ currency asset, net Total currency asset, net Total Beginning balance ​ $ (411.5) ​ $ 24.7 ​ $ (386.8) ​ $ (272.4) ​ $ 21.0 ​ $ (251.4) Other comprehensive income (loss) ​ ​ (37.3) ​ ​ — ​ ​ (37.3) ​ ​ (104.7) ​ ​ — ​ ​ (104.7) Less: other comprehensive loss (income) attributable to noncontrolling interests ​ ​ 0.1 ​ ​ — ​ ​ 0.1 ​ ​ 0.6 ​ ​ — ​ ​ 0.6 Ending balance ​ $ (448.7) ​ $ 24.7 ​ $ (424.0) ​ $ (376.5) ​ $ 21.0 ​ $ (355.5) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six months ended June 30, ​ ​ 2019 ​ 2018 ​ ​ Foreign ​ Retirement benefit ​ ​ ​ ​ Foreign ​ Retirement ​ ​ ​ ​ currency asset, net Total currency asset, net Total Beginning balance ​ $ (448.2) ​ $ 24.7 ​ $ (423.5) ​ $ (325.3) ​ $ 21.0 ​ $ (304.3) Other comprehensive income ​ ​ (0.5) ​ ​ — ​ ​ (0.5) ​ ​ (52.0) ​ ​ — ​ ​ (52.0) Less: other comprehensive loss (income) attributable to noncontrolling interests ​ ​ — ​ ​ — ​ ​ — ​ ​ 0.8 ​ ​ — ​ ​ 0.8 Ending balance ​ $ (448.7) ​ $ 24.7 ​ $ (424.0) ​ $ (376.5) ​ $ 21.0 ​ $ (355.5) ​
Components of other comprehensive income (loss), net of tax	The components of other comprehensive income, net of tax for the three and six months ended June 30, 2019 and 2018, are as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended June 30, ​ ​ 2019 ​ 2018 ​ ​ Pre-tax ​ Tax ​ ​ ​ Pre-tax ​ Tax ​ ​ ​ amount impact Net amount amount impact Net amount Foreign currency translation adjustments ​ $ (37.7) ​ $ 0.4 ​ $ (37.3) ​ $ (104.7) ​ $ — ​ $ (104.7) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six months ended June 30, ​ ​ 2019 ​ 2018 ​ ​ Pre-tax ​ Tax ​ ​ ​ Pre-tax ​ Tax ​ ​ ​ amount impact Net amount amount impact Net amount Foreign currency translation adjustments ​ $ (2.4) ​ $ 1.9 ​ $ (0.5) ​ $ (52.0) ​ $ — ​ $ (52.0) ​

Changes in Equity (Tables)

Changes in Equity (Tables)	6 Months Ended
	Jun. 30, 2019
Changes in Equity
Schedule of changes in equity for current and previous years' quarter	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended June 30, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Additional ​ ​ ​ ​ ​ other ​ ​ ​ ​ ​ Nonredeemable ​ ​ ​ ​ ​ Number of ​ ​ Common ​ ​ paid-in ​ ​ Treasury ​ ​ comprehensive ​ ​ Retained ​ ​ noncontrolling ​ ​ Total ​ ​ shares ​ ​ stock ​ ​ capital ​ ​ shares ​ ​ loss ​ ​ earnings ​ ​ interests ​ ​ equity Balance at April 1, 2019 ​ 195.2 ​ $ 292.7 ​ $ 3,802.1 ​ $ (165.4) ​ $ (386.8) ​ $ 1,309.9 ​ $ 22.6 ​ $ 4,875.1 Net income ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 109.4 ​ ​ 0.2 ​ ​ 109.6 Other comprehensive loss ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (37.2) ​ — ​ ​ — ​ (37.2) Dividends paid to shareholders ​ — ​ ​ — ​ ​ 0.1 ​ ​ — ​ — ​ ​ (68.7) ​ ​ — ​ (68.6) Share buyback program ​ (3.6) ​ ​ (5.2) ​ ​ — ​ ​ — ​ ​ — ​ ​ (70.0) ​ ​ — ​ ​ (75.2) Distributions to noncontrolling interests ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (0.4) ​ ​ (0.4) Fair value adjustments to redeemable noncontrolling interests ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 0.2 ​ ​ — ​ ​ 0.2 Purchase of common stock for stock-based compensation plans — ​ — ​ ​ (1.8) ​ ​ 0.8 ​ — ​ ​ — ​ ​ — ​ (1.0) Vesting of stock-based compensation plans ​ — ​ ​ — ​ ​ (16.8) ​ ​ 16.8 ​ — ​ ​ — ​ ​ — ​ — Stock-based compensation plan expense ​ — ​ — ​ ​ 18.0 ​ ​ — ​ — ​ ​ — ​ ​ — ​ 18.0 Balance at June 30, 2019 ​ 191.6 ​ $ 287.5 ​ $ 3,801.6 ​ $ (147.8) ​ $ (424.0) ​ $ 1,280.8 ​ $ 22.4 ​ $ 4,820.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended June 30, 2018 ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Additional ​ ​ ​ ​ ​ other ​ ​ ​ ​ ​ Nonredeemable ​ ​ ​ ​ ​ Number of ​ ​ Common ​ ​ paid-in ​ ​ Treasury ​ ​ comprehensive ​ ​ Retained ​ ​ noncontrolling ​ ​ Total ​ ​ shares ​ ​ stock ​ ​ capital ​ ​ shares ​ ​ loss ​ ​ earnings ​ ​ interests ​ ​ equity Balance at April 1, 2018 ​ 200.4 ​ $ 300.6 ​ $ 3,786.0 ​ $ (198.9) ​ $ (251.4) ​ $ 1,255.9 ​ $ 34.7 ​ $ 4,926.9 Net income ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 140.6 ​ ​ (3.4) ​ ​ 137.2 Other comprehensive loss ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (104.1) ​ — ​ ​ — ​ (104.1) Dividends paid to shareholders ​ — ​ ​ — ​ ​ 0.1 ​ ​ — ​ — ​ ​ (71.7) ​ ​ — ​ (71.6) Distributions to noncontrolling interests ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (3.0) ​ ​ (3.0) Fair value adjustments to redeemable noncontrolling interests ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 0.1 ​ ​ — ​ ​ 0.1 Redemptions of convertible debt ​ — ​ ​ — ​ ​ (0.1) ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (0.1) Purchase of common stock for stock-based compensation plans — ​ — ​ ​ (0.2) ​ ​ (1.2) ​ — ​ ​ — ​ ​ — ​ (1.4) Vesting of stock-based compensation plans ​ — ​ ​ — ​ ​ (27.2) ​ ​ 27.2 ​ — ​ ​ — ​ ​ — ​ — Stock-based compensation plan expense ​ — ​ — ​ ​ 24.8 ​ ​ — ​ — ​ ​ — ​ ​ — ​ 24.8 Proceeds from stock-based compensation plans ​ — ​ ​ — ​ ​ 0.1 ​ ​ — ​ — ​ ​ — ​ ​ — ​ 0.1 Balance at June 30, 2018 ​ 200.4 ​ $ 300.6 ​ $ 3,783.5 ​ $ (172.9) ​ $ (355.5) ​ $ 1,324.9 ​ $ 28.3 ​ $ 4,908.9 ​

Earnings and Dividends Per Sh_2

Earnings and Dividends Per Share (Tables)	6 Months Ended
	Jun. 30, 2019
Summary of earnings per share calculation	The following is a summary of the earnings per share calculation for the three and six months ended June 30, 2019 and 2018 (in millions, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ 2019 2018 2019 2018 Net income attributable to JHG ​ $ 109.4 ​ $ 140.6 ​ $ 203.5 ​ $ 305.8 Less: allocation of earnings to participating stock-based awards ​ ​ (3.2) ​ ​ (3.8) ​ ​ (5.6) ​ ​ (7.6) Net income attributable to JHG common shareholders ​ $ 106.2 ​ $ 136.8 ​ $ 197.9 ​ $ 298.2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average common shares outstanding — basic ​ 190.2 ​ 195.8 ​ 191.1 ​ 195.9 Dilutive effect of non -participating stock-based awards ​ ​ 0.5 ​ ​ 0.8 ​ ​ 0.5 ​ ​ 1.3 Weighted-average common shares outstanding — diluted ​ 190.7 ​ 196.6 ​ 191.6 ​ 197.2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ $ 0.56 ​ $ 0.70 ​ $ 1.04 ​ $ 1.52 Diluted (two class) ​ $ 0.56 ​ $ 0.70 ​ $ 1.03 ​ $ 1.51 ​
Schedule of anti-dilutive securities that have not been included in the calculation of weighted average diluted shares outstanding	The following instruments are anti-dilutive and have not been included in the weighted-average diluted shares outstanding calculation (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ 2019 2018 2019 2018 Unvested nonparticipating stock awards 1.0 0.6 1.0 0.6 Dai-ichi options — 10.0 — 10.0 ​
Schedule of cash dividends declared and paid	The following is a summary of cash dividends paid during the three and six months ended June 30, 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ Dividend ​ Date ​ Dividends paid ​ Date per share declared ​ (in US$ millions) paid $ 0.36 ​ February 4, 2019 $ 69.7 ​ February 26, 2019 $ 0.36 ​ May 1, 2019 ​ $ 68.6 ​ May 29, 2019 ​

Basis of Presentation and Sig_3

Basis of Presentation and Significant Accounting Policies (Details) $ in Millions	Jan. 01, 2019USD ($)
Recent Accounting Pronouncements
Practical expedients - reassessing the leases	true
Accounting Standards Update 2016-02
Recent Accounting Pronouncements
Right of use assets	$ 129.8
Lease liability	$ 146.4

Consolidation - VIEs (Details)

Consolidation - VIEs (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Unconsolidated VIEs
Investment securities	$ 3.7	$ 3.1

Consolidation - VREs (Details)

Consolidation - VREs (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Other current assets	$ 108.8	$ 69.4
Consolidated VREs
Investment securities	9.3	13.9
Cash and cash equivalents	0.1	1.4
Other current assets	0.2	0.1
Accounts payable and accrued liabilities	(0.1)	(0.1)
Total	9.5	15.3
Redeemable noncontrolling interests in consolidated VREs	(4.3)	(6)
JHG's net interest in consolidated VREs	5.2	9.3
Unconsolidated VREs
Investment securities	$ 28.4	$ 50.7

Investment Securities - General

Investment Securities - General Disclosure (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Short-term investments:
Estimated Fair Value	$ 557.9		$ 557.9		$ 574.5
Unrealized gains (losses) on investment securities held at period end	4.6	$ (13.6)	15.7	$ (21.5)
Net gains (losses) in net income related to:
Foreign currency translation	(1.2)	(3.3)	(0.9)	(3.8)
Foreign currency forward contracts	1.2	$ 3.3	0.9	$ 3.8
Seeded investment products
Short-term investments:
Seeded investment products	419.8		419.8		447.5
Investment securities | Separate accounts
Short-term investments:
Seeded investment products	56.7		56.7		71.6
Investment securities | Pooled investment funds
Short-term investments:
Seeded investment products	10.6		10.6		25.5
Investment securities | Investments related to deferred compensation plans
Short-term investments:
Estimated Fair Value	132.6		132.6		120.3
Investment securities | Other investments
Short-term investments:
Estimated Fair Value	5.5		5.5		6.7
Consolidated VIEs | Investment securities
Short-term investments:
Seeded investment products	311.1		311.1		282.7
Consolidated VREs | Investment securities
Short-term investments:
Seeded investment products	9.3		9.3		13.9
Unconsolidated VIEs and VREs | Investment securities
Short-term investments:
Seeded investment products	32.1		32.1		53.8
Consolidated | Credit default swap, selling protection contracts | Seeded investment products
Available-for-sale securities.
Notional value of derivative	2.3		2.3		3.9
Futures | Derivative Instruments | Not Designated as Hedging Instrument
Available-for-sale securities.
Notional value of derivative	103.5		103.5		147.1
Futures | Derivative Instruments | Seeded investment products
Available-for-sale securities.
Notional value of derivative	102.2		102.2		267.8
Credit default swaps | Derivative Instruments | Not Designated as Hedging Instrument
Available-for-sale securities.
Notional value of derivative	93		93		133.2
Credit default swaps | Derivative Instruments | Seeded investment products
Available-for-sale securities.
Notional value of derivative	2.4		2.4		6.2
Total return swaps | Derivative Instruments | Seeded investment products
Available-for-sale securities.
Notional value of derivative	37.8		37.8		23.7
Total return swaps and index swaps | Derivative Instruments | Not Designated as Hedging Instrument
Available-for-sale securities.
Notional value of derivative	75.8		75.8		77.2
Foreign currency forward contracts | Derivative Instruments | Not Designated as Hedging Instrument
Available-for-sale securities.
Notional value of derivative	163.6		163.6		131.8
Foreign currency forward contracts | Derivative Instruments | Seeded investment products
Available-for-sale securities.
Notional value of derivative	$ 147.2		$ 147.2		$ 154.9

Investment Securities - Offsett

Investment Securities - Offsetting Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Derivative Instrument Denominated in Foreign Currency
Investment gains (losses), net	$ 4.8	$ (16.6)	$ 18.1	$ (17.3)
Cash flows related to investment securities
Purchases and settlements			57.5	43.9
Seeded investment products | Consolidated | Credit default swap, selling protection contracts
Seeded investment products, credit protection
Notional value of derivative	2.3		2.3		$ 3.9
Fair value of credit default swap contracts	0		$ 0		0.1
Seeded investment products | Consolidated | Credit default swap, selling protection contracts | Minimum
Seeded investment products, credit protection
Term of credit default swap contracts (in years)			1 year
Seeded investment products | Consolidated | Credit default swap, selling protection contracts | Maximum
Seeded investment products, credit protection
Term of credit default swap contracts (in years)			5 years
Seeded investment products and derivatives
Derivative Instrument Denominated in Foreign Currency
Investment gains (losses), net	3.4	(17.4)	$ 11.6	(18.2)
Other investments
Derivative Instrument Denominated in Foreign Currency
Investment gains (losses), net	1.4	$ 0.8	6.5	0.9
Investment securities
Cash flows related to investment securities
Purchases and settlements			(269.1)	(30.9)
Sales, settlements and maturities			246.9	$ 58.1
Derivative Instruments | Seeded investment products | Futures
Seeded investment products, credit protection
Notional value of derivative	102.2		102.2		267.8
Derivative Instruments | Seeded investment products | Contracts for differences
Seeded investment products, credit protection
Notional value of derivative	10.4		10.4		8.7
Derivative Instruments | Seeded investment products | Interest rate swaps
Seeded investment products, credit protection
Notional value of derivative	26.2		26.2		61.5
Derivative Instruments | Seeded investment products | Total return swaps
Seeded investment products, credit protection
Notional value of derivative	37.8		37.8		23.7
Derivative Instruments | Seeded investment products | Credit default swaps
Seeded investment products, credit protection
Notional value of derivative	2.4		2.4		6.2
Derivative Instruments | Seeded investment products | Options
Seeded investment products, credit protection
Notional value of derivative	0.7		0.7		9.6
Derivative Instruments | Seeded investment products | Swaptions
Seeded investment products, credit protection
Notional value of derivative					8.3
Derivative Instruments | Seeded investment products | Foreign currency forward contracts
Seeded investment products, credit protection
Notional value of derivative	$ 147.2		$ 147.2		$ 154.9

Fair Value Measurements - Level

Fair Value Measurements - Level of Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Liabilities
Total redeemable noncontrolling interests	$ 153.6		$ 136.1
Seeded investment products
Liabilities
Total redeemable noncontrolling interests	138.8	$ 122	121.6	$ 163	$ 202.9	$ 174.9
Unconsolidated VIEs
Assets
Total investment securities	3.7		3.1
Intech Founders
Liabilities
Total redeemable noncontrolling interests	3.4		3.6
Consolidated | Seeded investment products
Liabilities
Total redeemable noncontrolling interests	138.8		121.6
Consolidated VIEs
Assets
Total investment securities	311.1		282.7
Fair value measurements, recurring
Assets
Cash equivalents	270.5		381.8
Contingent consideration	3.3		3.9
Total assets	833.8		964.3
Liabilities
Long-term debt	324.3		301.4
Contingent consideration	31.8		61.3
Total liabilities	424.7		434.8
Total redeemable noncontrolling interests	153.6		136.1
Fair value measurements, recurring | Deferred bonuses
Liabilities
Derivative liabilities	60.7
Current portion of long-term debt			68.5
Fair value measurements, recurring | Investment securities
Assets
Total investment securities	557.9		574.5
Fair value measurements, recurring | Seed hedge derivatives
Assets
Derivative assets	2.1		3.2
Liabilities
Derivative liabilities	6.4		1.1
Fair value measurements, recurring | Level 1
Assets
Cash equivalents	270.5		381.8
Total assets	588.7		680.1
Liabilities
Total liabilities			0.4
Fair value measurements, recurring | Level 1 | Investment securities
Assets
Total investment securities	318.2		298.3
Fair value measurements, recurring | Level 2
Assets
Total assets	226		261.1
Liabilities
Long-term debt	324.3		301.4
Total liabilities	332.2		304.6
Fair value measurements, recurring | Level 2 | Investment securities
Assets
Total investment securities	223.9		257
Fair value measurements, recurring | Level 2 | Seed hedge derivatives
Assets
Derivative assets	2.1		3.2
Liabilities
Derivative liabilities	6.4		1.1
Fair value measurements, recurring | Level 3
Assets
Contingent consideration	3.3		3.9
Total assets	19.1		23.1
Liabilities
Contingent consideration	31.8		61.3
Total liabilities	92.5		129.8
Total redeemable noncontrolling interests	153.6		136.1
Fair value measurements, recurring | Level 3 | Deferred bonuses
Liabilities
Derivative liabilities	60.7
Current portion of long-term debt			68.5
Fair value measurements, recurring | Level 3 | Investment securities
Assets
Total investment securities	15.8		19.2
Fair value measurements, recurring | Unconsolidated VIEs | Investment securities
Assets
Total investment securities	246.8		291.8
Fair value measurements, recurring | Unconsolidated VIEs | Level 1 | Investment securities
Assets
Total investment securities	185.3		194.5
Fair value measurements, recurring | Unconsolidated VIEs | Level 2 | Investment securities
Assets
Total investment securities	61.5		97.3
Fair value measurements, recurring | Intech
Liabilities
Total redeemable noncontrolling interests	14.8		14.5
Fair value measurements, recurring | Intech | Level 3
Liabilities
Total redeemable noncontrolling interests	14.8		14.5
Fair value measurements, recurring | Consolidated | Seeded investment products
Assets
Derivative assets			0.9
Liabilities
Derivative liabilities	1.5		2.1
Financial liabilities in consolidated seeded investment products			0.4
Total redeemable noncontrolling interests	138.8		121.6
Fair value measurements, recurring | Consolidated | Level 1 | Seeded investment products
Liabilities
Financial liabilities in consolidated seeded investment products			0.4
Fair value measurements, recurring | Consolidated | Level 2 | Seeded investment products
Assets
Derivative assets			0.9
Liabilities
Derivative liabilities	1.5		2.1
Fair value measurements, recurring | Consolidated | Level 3 | Seeded investment products
Liabilities
Total redeemable noncontrolling interests	138.8		121.6
Fair value measurements, recurring | Consolidated VIEs | Investment securities
Assets
Total investment securities	311.1		282.7
Fair value measurements, recurring | Consolidated VIEs | Level 1 | Investment securities
Assets
Total investment securities	132.9		103.8
Fair value measurements, recurring | Consolidated VIEs | Level 2 | Investment securities
Assets
Total investment securities	162.4		159.7
Fair value measurements, recurring | Consolidated VIEs | Level 3 | Investment securities
Assets
Total investment securities	$ 15.8		$ 19.2

Fair Value Measurements - Valua

Fair Value Measurements - Valuation techniques and significant unobservable inputs (Details) - Consolidated VIEs - Level 3 - Fair value measurements, recurring - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Changes in fair value
Investment securities	$ 15.8	$ 19.2
Discounted cash flow
Changes in fair value
Discount rate	15.00%	15.00%
EBITDA multiple	16.40%	18.50%
Price-earnings ratio	27.7	28.4

Fair Value Measurements - Conti

Fair Value Measurements - Contingent Consideration (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Geneva
Contingent Consideration
Maximum amount payable	$ 61.3
Fair value included in:
Other non-current liabilities	6.6	$ 25.3
Total fair value	6.6	25.3
Perennial
Contingent Consideration
Maximum amount payable	15.8
Fair value included in:
Accounts payable and accrued liabilities	12
Other non-current liabilities		9.9
Total fair value	12	9.9
Kapstream
Contingent Consideration
Maximum amount payable	13.8
Fair value included in:
Accounts payable and accrued liabilities	13.2	13.8
Other non-current liabilities		12.3
Total fair value	$ 13.2	$ 26.1

Fair Value Measurements - Acqui

Fair Value Measurements - Acquisition of Geneva (Details) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Dec. 31, 2014tranche
Acquisitions
Contingent consideration fair value adjustment		$ (20)
Increase in contingency liability due to unwind of discount		$ (20)
Geneva
Acquisitions
Number of contingent consideration payment tranches | tranche			2
Contingent consideration payable period			6 years
Geneva | Other non-operating income (expenses), net
Acquisitions
Contingent consideration fair value adjustment	$ (20)
Increase in contingency liability due to unwind of discount	$ (20)

Fair Value Measurements - Acq_2

Fair Value Measurements - Acquisition of Perennial (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Acquisitions
Contingent consideration fair value adjustment		$ (20)
Perennial
Acquisitions
Decrease in earn-out accruals	$ 2.1

Fair Value Measurements - Acq_3

Fair Value Measurements - Acquisition of Kapstream (Details) $ in Millions	1 Months Ended		3 Months Ended	6 Months Ended
	Feb. 28, 2019USD ($)	Feb. 28, 2018USD ($)	Jun. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Dec. 31, 2018USD ($)	Jan. 31, 2017USD ($)item
Business acquisition
Contingent consideration fair value adjustment				$ (20)
Kapstream
Business acquisition
Ownership interest acquired (as a percent)						49.00%
Contingent cash consideration paid, for revenue target achieved	$ 14.1	$ 15.3
Fair value of contingent consideration liability			$ 13.2	13.2	$ 26.1
Number of installments | item						3
Contingent consideration fair value adjustment			$ 0	$ 0
Kapstream | Maximum
Business acquisition
Fair value of contingent consideration liability						$ 43

Fair Value Measurements - Dispo

Fair Value Measurements - Disposal of Volantis (Details) - USD ($) $ in Millions	Apr. 01, 2017	Jun. 30, 2019	Dec. 31, 2018
Disposal of Volantis
Revenue forecasting period		3 years
Volantis
Disposal of Volantis
Period of performance of investee for recognizing consideration	3 years
Volantis | Discontinued Operations, Disposed of by Sale
Disposal of Volantis
Percentage of share for consideration of sale	10.00%
Fair value of contingent consideration		$ 3.3	$ 3.9

Fair Value Measurements - Lev_2

Fair Value Measurements - Level 3 Rollforward (Details) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2019USD ($)	Jun. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Changes in fair value
Foreign currency translation	$ (1.2)	$ (3.3)	$ (0.9)	$ (3.8)
Change in fair value of Level 3 assets
Balance at the beginning of period, Asset value	19.8	47.2	23.1	46.5	$ 46.5
Settlements	(0.9)	(1.8)	(1.2)	(2.2)
Movements recognized in net income	0.2	(6.1)	(2.9)	(5.3)
Movements recognized in other comprehensive income		(0.6)	0.1	(0.3)
Balance at the end of period, Asset value	19.1	38.7	19.1	38.7	23.1
Consolidated VIEs
Changes in fair value
Investment securities	311.1		311.1		282.7
Level 3 | Fair value measurements, recurring | Consolidated VIEs
Changes in fair value
Investment securities	15.8		$ 15.8		$ 19.2
Level 3 | Fair value measurements, recurring | Discounted cash flow | Consolidated VIEs
Changes in fair value
Price-earnings ratio			27.7		28.4
Level 3 | Fair value measurements, recurring | Contingent consideration
Changes in fair value
Balance at the beginning of period, Liability Value	49.8	59.2	$ 61.3	76.6	$ 76.6
Fair value adjustments	(20)	(0.2)	(20)	1.8
Unrealized gains (losses)	2.4		4.8
Distributions			(14.1)	(18.8)
Foreign currency translation	(0.4)	(1.7)	(0.2)	(2.3)
Balance at the end of period, Liability Value	31.8	57.3	31.8	57.3	61.3
Level 3 | Fair value measurements, recurring | Deferred bonuses
Changes in fair value
Balance at the beginning of period, Liability Value	83.1	79.5	68.5	64.7	64.7
Net movement in bonus deferrals	(22.4)	(15.2)	(7.8)	(0.4)
Balance at the end of period, Liability Value	60.7	64.3	60.7	64.3	68.5
Level 3 | Fair value measurements, recurring | Dai-ichi options
Changes in fair value
Balance at the beginning of period, Liability Value		4.3		26.1	26.1
Fair value adjustments		(1.9)		(24.7)
Foreign currency translation		(0.3)		0.7
Balance at the end of period, Liability Value		2.1		2.1
Level 3 | Fair value measurements, recurring | Redeemable noncontrolling interests
Changes in fair value
Balance at the beginning of period, Liability Value	137	217.7	136.1	190.3	190.3
Changes in ownership	18.2	(32.6)	14.2	(5.5)
Fair value adjustments		(0.2)		0.2
Unrealized gains (losses)	(1.6)	(6.5)	3	(5.4)
Amortization of Intech appreciation rights	0.3	0.3	0.6	(0.6)
Distributions	(0.3)	(0.3)	(0.3)	(0.4)
Foreign currency translation		(0.6)		(0.8)
Balance at the end of period, Liability Value	$ 153.6	$ 177.8	$ 153.6	$ 177.8	$ 136.1

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Jun. 30, 2018
Indefinite-lived intangible assets:
Impairment		$ (18)
Definite-lived intangible assets:
Accumulated amortization, balance at the beginning of the period		(116.3)	$ (89.7)
Amortization		(14.7)	(14.8)
Foreign currency translation		(0.1)	1.3
Accumulated amortization, balance at the end of the period	$ (130.9)	(130.9)	(103.2)
Net intangible assets
Net intangible assets, balance at the beginning of the period		3,123.3	3,204.8
Amortization		(14.7)	(14.8)
Impairment		(18)
Foreign currency translation		0.9	(22)
Net intangible assets, balance at the end of the period	3,089.7	3,089.7	3,168
Goodwill
Goodwill, balance at the beginning of the period		1,478	1,533.9
Foreign currency translation		(0.6)	(19.9)
Disposal			(9.5)
Goodwill, balance at the end of the period	1,477.4	1,477.4	1,504.5
Impairment		18
Transaction with BNP Paribas
Allocated goodwill			9.5
Disposal			(9.5)
Future Amortization:
2019 (remainder of year)	14.7	14.7
2020	29.4	29.4
2021	26.5	26.5
2022	18	18
2023	17.8	17.8
Thereafter	125.9	125.9
Total	232.3	232.3
Client relationships
Definite-lived intangible assets:
Balance at the beginning of the period		363.3	369.4
Foreign currency translation		(0.1)	(3)
Balance at the end of the period	363.2	363.2	366.4
Investment management agreements
Indefinite-lived intangible assets:
Balance at the beginning of the period		2,495.5	2,543.9
Impairment	(18)	(18)
Foreign currency translation		(0.9)	(20)
Balance at the end of the period	2,476.6	2,476.6	2,523.9
Goodwill
Impairment	18	18
Trademarks
Indefinite-lived intangible assets:
Balance at the beginning of the period		380.8	381.2
Foreign currency translation			(0.3)
Balance at the end of the period	$ 380.8	$ 380.8	$ 380.9

Leases - (Details)

Leases - (Details)	6 Months Ended
	Jun. 30, 2019
Leases
Option to extend - Operating	true
Option to extend - Finance	true
Option to terminate - Operating	true
Option to terminate - Finance	true
Minimum
Leases
Remaining lease term	1 year
Maximum
Leases
Remaining lease term	10 years

Leases - Balance Sheet (Details

Leases - Balance Sheet (Details) $ in Millions	Jun. 30, 2019USD ($)
Leases
Operating lease right-of-use assets	$ 138.1
Financial position	us-gaap:OtherAssetsNoncurrent
Operating lease liabilities - current	$ 26.4
Financial position	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent
Operating lease liabilities - noncurrent	$ 133.4
Financial position	us-gaap:OtherLiabilitiesNoncurrent
Total Operating lease liabilities	$ 159.8
Property and equipment, at cost	13
Accumulated depreciation	(11.6)
Finance lease right-of-use assets	$ 1.4
Financial position	us-gaap:PropertyPlantAndEquipmentNet
Finance lease liabilities - current	$ 0.9
Financial position	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent
Finance lease liabilities - noncurrent	$ 0.6
Financial position	us-gaap:OtherLiabilitiesNoncurrent
Total Finance lease liabilities	$ 1.5

Leases - Statement of Comprehen

Leases - Statement of Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Components of lease cost:
Operating lease expense	$ 8.6	$ 19.5
Amortization of right-of-use asset	0.3	0.6
Total finance lease cost	0.3	0.6
Sublease income	1.9	3.6
Impairment loss		4.7
UK
Components of lease cost:
Impairment loss		$ 4.7
U.S.
Components of lease cost:
Impairment loss	$ 0.5

Leases - Cash Flow Statement (D

Leases - Cash Flow Statement (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Leases
Operating cash flows from operating leases	$ 17.4
Financing cash flows from finance leases	0.6	$ 0.7
Non-cash recognition of ROU asset	19.8
Non-cash recognition of lease liability	$ 19.8
Term of lease that has not yet commenced	11 years
Future rent obligation of operating least that has not yet commenced	$ 8.4

Leases - Supplemental Informati

Leases - Supplemental Information (Details)	Jun. 30, 2019
Leases
Operating leases -Weighted-average remaining lease term (in months)	85 months
Finance leases - Weighted-average remaining lease term (in months)	19 months
Operating leases - Weighted-average discount rate	4.50%
Finance leases - Weighted-average discount rate	2.70%

Leases - Future lease obligatio

Leases - Future lease obligations (Details) $ in Millions	Jun. 30, 2019USD ($)
Operating future lease obligations:
2019 (excluding three months ended March 31, 2019)	$ 16.1
2020	30.5
2021	28.2
2022	24.1
2023	22.2
Thereafter	68.2
Total lease payments	189.3
Less interest	29.5
Total	159.8
Finance leases maturities:
2019 (excluding three months ended March 31, 2019)	0.6
2020	0.7
2021	0.1
2022	0.1
Total lease payments	1.5
Total	$ 1.5

Debt (Details)

Debt (Details) $ in Millions	6 Months Ended
	Jun. 30, 2019USD ($)	Dec. 31, 2018USD ($)
4.875% Senior Notes due 2025
Components of debt
Interest rate (as a percent)	4.875%
Other Disclosures
Face value of debt issued	$ 300
4.875% Senior Notes due 2025 | Carrying value
Components of debt
Total debt	317.7	$ 319.1
4.875% Senior Notes due 2025 | Fair value
Components of debt
Total debt	324.3	$ 301.4
Credit Facility
Other Disclosures
Credit facility, maximum borrowing capacity	$ 200
Credit facility covenant terms, financing leverage ratio, maximum	3
Borrowings under the Credit Facility	$ 0
Janus Capital Group Inc | 4.875% Senior Notes due 2025
Other Disclosures
Unamortized premium, net	$ 17.7

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Income Tax Contingency [Line Items]
Effective tax rate (as a percent)	24.00%	22.60%	23.50%	22.60%
Unrecognized tax liability	$ 12.1		$ 12.1		$ 12.4
Anticipated decrease in income tax contingency reserves in the next 12 months	$ 1.1		$ 1.1

Noncontrolling Interests - Rede

Noncontrolling Interests - Redeemable (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Jun. 30, 2019
Redeemable Noncontrolling Interests
Total redeemable noncontrolling interests	$ 153.6		$ 153.6		$ 136.1	$ 153.6
Roll forward of redeemable noncontrolling interests in consolidated seed investment products
Opening balance			136.1
Closing balance	153.6		153.6		136.1
Seeded investment products
Redeemable Noncontrolling Interests
Total redeemable noncontrolling interests	122	$ 202.9	121.6	$ 174.9	121.6	138.8
Roll forward of redeemable noncontrolling interests in consolidated seed investment products
Opening balance	122	202.9	121.6	174.9	174.9
Changes in market value	2.7	(6.7)	7.2	(5.6)
Changes in ownership	14.2	(32.6)	10	(5.5)
Foreign currency translation	(0.1)	(0.6)		(0.8)
Closing balance	138.8	$ 163	138.8	$ 163	121.6
Intech Founders
Redeemable Noncontrolling Interests
Total redeemable noncontrolling interests	3.4		3.6		3.6	$ 3.4
Roll forward of redeemable noncontrolling interests in consolidated seed investment products
Opening balance			3.6
Closing balance	3.4		3.4		3.6
Remaining interest (as a percent)						1.10%
Consolidated | Seeded investment products
Redeemable Noncontrolling Interests
Total redeemable noncontrolling interests	138.8		138.8		121.6	$ 138.8
Roll forward of redeemable noncontrolling interests in consolidated seed investment products
Opening balance			121.6
Closing balance	$ 138.8		138.8		121.6
Intech | Intech
Redeemable Noncontrolling Interests
INTECH appreciation rights			$ 11.4		$ 10.9

Noncontrolling Interests - Nonr

Noncontrolling Interests - Nonredeemable (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Nonredeemable noncontrolling interests
Total nonredeemable noncontrolling interests	$ 22.4	$ 21.5
Seeded investment products
Nonredeemable noncontrolling interests
Total nonredeemable noncontrolling interests	9.4	8.3
Intech
Nonredeemable noncontrolling interests
Total nonredeemable noncontrolling interests	$ 13	$ 13.2

Long-Term Incentive and Emplo_2

Long-Term Incentive and Employee Compensation (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Long-Term Incentive and Employee Compensation
Long-term incentive awards granted	$ 4.5	$ 153.9
Maximum
Long-Term Incentive and Employee Compensation
Vesting period		4 years
Minimum
Long-Term Incentive and Employee Compensation
Vesting period		3 years

Retirement benefit plans - Actu

Retirement benefit plans - Actuarial gains(losses), benefit cost, cash flows (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Components of net periodic benefit cost
Service cost	$ (0.3)	$ (0.3)	$ (0.6)	$ (0.6)
Interest cost	(4.6)	(4.2)	(9.3)	(9)
Expected return on plan assets	5.2	5.4	10.6	11.5
Net periodic benefit credit	$ 0.3	$ 0.9	$ 0.7	$ 1.9

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Changes in accumulated other comprehensive loss, net of tax
Beginning balance			$ 4,839.3
Less: other comprehensive loss (income) attributable to noncontrolling interests	$ 0.1	$ 0.6		$ 0.8
Ending balance	4,798.1		4,798.1
Accumulated other comprehensive loss
Changes in accumulated other comprehensive loss, net of tax
Beginning balance	(386.8)	(251.4)	(423.5)	(304.3)
Other comprehensive income	(37.3)	(104.7)	(0.5)	(52)
Less: other comprehensive loss (income) attributable to noncontrolling interests	0.1	0.6		0.8
Ending balance	(424)	(355.5)	(424)	(355.5)
Foreign currency translation adjustments
Changes in accumulated other comprehensive loss, net of tax
Beginning balance	(411.5)	(272.4)	(448.2)	(325.3)
Other comprehensive income	(37.3)	(104.7)	(0.5)	(52)
Less: other comprehensive loss (income) attributable to noncontrolling interests	0.1	0.6		0.8
Ending balance	(448.7)	(376.5)	(448.7)	(376.5)
Retirement benefit asset, net
Changes in accumulated other comprehensive loss, net of tax
Beginning balance	24.7	21	24.7	21
Ending balance	$ 24.7	$ 21	$ 24.7	$ 21

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Loss - OCI (Details) - Foreign currency translation adjustments - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Other comprehensive income, net of tax
Pre-tax amount	$ (37.7)	$ (104.7)	$ (2.4)	$ (52)
Tax impact	(0.4)		1.9
Net amount	$ (37.3)	$ (104.7)	$ (0.5)	$ (52)

Changes in Equity (Details)

Changes in Equity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Increase (Decrease) in Stockholders' Equity
Balance	$ 4,875.1	$ 4,926.9	$ 4,860.8	$ 4,875.7
Balance (in shares)			196,412,764
Net income	109.6	137.2	$ 204.9	299
Other comprehensive loss	(37.2)	(104.1)	(0.5)	(51.2)
Dividends paid to shareholders	(68.6)	(71.6)	(138.3)	(134.7)
Share buyback program	(75.2)		(106.1)
Distributions to noncontrolling interests	(0.4)	(3)	(0.5)	(3.1)
Fair value adjustments to redeemable noncontrolling interests	0.2	0.1	0.2	(0.2)
Redemptions of convertible debt		(0.1)		(34)
Purchase of common stock for stock-based compensation plans	(1)	(1.4)	(38.1)	(84.1)
Stock-based compensation plan expense	18	24.8	38.1	41.2
Proceeds from stock-based compensation plans		0.1		0.3
Balance	$ 4,820.5	4,908.9	$ 4,820.5	4,908.9
Balance (in shares)	191,647,272		191,647,272
Common stock
Increase (Decrease) in Stockholders' Equity
Balance	$ 292.7	$ 300.6	$ 294.6	$ 300.6
Balance (in shares)	195,200,000	200,400,000	196,400,000	200,400,000
Share buyback program	$ (5.2)		$ (7.1)
Share buyback program (in shares)	(3,600,000)		(4,800,000)
Balance	$ 287.5	$ 300.6	$ 287.5	$ 300.6
Balance (in shares)	191,600,000	200,400,000	191,600,000	200,400,000
Additional paid-in-capital
Increase (Decrease) in Stockholders' Equity
Balance	$ 3,802.1	$ 3,786	$ 3,824.5	$ 3,842.9
Dividends paid to shareholders	0.1	0.1	0.1	0.1
Redemptions of convertible debt		(0.1)		(34)
Purchase of common stock for stock-based compensation plans	(1.8)	(0.2)	(33.2)	(37.5)
Vesting of stock-based compensation plans	(16.8)	(27.2)	(27.9)	(29.5)
Stock-based compensation plan expense	18	24.8	38.1	41.2
Proceeds from stock-based compensation plans		0.1		0.3
Balance	3,801.6	3,783.5	3,801.6	3,783.5
Treasury shares
Increase (Decrease) in Stockholders' Equity
Balance	(165.4)	(198.9)	(170.8)	(155.8)
Purchase of common stock for stock-based compensation plans	0.8	(1.2)	(4.9)	(46.6)
Vesting of stock-based compensation plans	16.8	27.2	27.9	29.5
Balance	(147.8)	(172.9)	(147.8)	(172.9)
Accumulated other comprehensive loss
Increase (Decrease) in Stockholders' Equity
Balance	(386.8)	(251.4)	(423.5)	(304.3)
Other comprehensive loss	(37.2)	(104.1)	(0.5)	(51.2)
Balance	(424)	(355.5)	(424)	(355.5)
Retained earnings
Increase (Decrease) in Stockholders' Equity
Balance	1,309.9	1,255.9	1,314.5	1,154.1
Net income	109.4	140.6	203.5	305.8
Dividends paid to shareholders	(68.7)	(71.7)	(138.4)	(134.8)
Share buyback program	(70)		(99)
Fair value adjustments to redeemable noncontrolling interests	0.2	0.1	0.2	(0.2)
Balance	1,280.8	1,324.9	1,280.8	1,324.9
Nonredeemable noncontrolling interests
Increase (Decrease) in Stockholders' Equity
Balance	22.6	34.7	21.5	38.2
Net income	0.2	(3.4)	1.4	(6.8)
Distributions to noncontrolling interests	(0.4)	(3)	(0.5)	(3.1)
Balance	$ 22.4	$ 28.3	$ 22.4	$ 28.3

Earnings and Dividends Per Sh_3

Earnings and Dividends Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Jul. 30, 2019	May 29, 2019	May 02, 2019	Feb. 26, 2019	Feb. 04, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings per share
Net income attributable to JHG						$ 109.4	$ 140.6	$ 203.5	$ 305.8
Less: Allocation of earnings to participating stock-based awards						(3.2)	(3.8)	(5.6)	(7.6)
Net income attributable to JHG common shareholders						$ 106.2	$ 136.8	$ 197.9	$ 298.2
Weighted-average common shares outstanding - basic						190.2	195.8	191.1	195.9
Dilutive effect of non-participating stock-based awards						0.5	0.8	0.5	1.3
Weighted-average common shares outstanding - diluted						190.7	196.6	191.6	197.2
Earnings per share:
Basic (in dollars per share)						$ 0.56	$ 0.70	$ 1.04	$ 1.52
Diluted (two class) (in dollars per share)						$ 0.56	$ 0.70	$ 1.03	$ 1.51
Dividends Per Share
Cash dividend declared (in dollars per share)	$ 0.36		$ 0.36		$ 0.36
Cash dividends paid		$ 68.6		$ 69.7				$ 138.3	$ 134.7
Unvested nonparticipating stock awards
Anti-dilutive securities that have not been included in the calculation of weighted average diluted shares outstanding
Number of anti-dilutive securities that have not been included in the calculation of weighted average diluted shares outstanding						1	0.6	1	0.6
Dai-ichi options
Anti-dilutive securities that have not been included in the calculation of weighted average diluted shares outstanding
Number of anti-dilutive securities that have not been included in the calculation of weighted average diluted shares outstanding							10		10

Commitments and Contingencies (

Commitments and Contingencies (Details) - Richard Pease Versus Henderson Administration Limited - USD ($) $ in Millions	Feb. 15, 2019	Jun. 30, 2018
Charges related to case		$ 12.2
Fund Transfer Fees awarded to the Group	$ 5
Interest awarded	$ 0.3