Condensed Consolidated Statements of Changes in Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Consolidated Funds	Ordinary shares Investments in unconsolidated Funds	Additional Paid-in Capital Investments in unconsolidated Funds	Retained earnings (deficit) Investments in unconsolidated Funds	Accumulated other comprehensive income (loss) Investments in unconsolidated Funds	Total shareholders’ equity Investments in unconsolidated Funds	Non- controlling interests Investments in unconsolidated Funds	Non- controlling interests Consolidated Funds
Beginning balance (in shares) at Dec. 31, 2018			105.2
Beginning balance at Dec. 31, 2018	$ 134.2		$ 0.1	$ 764.6	$ (640.5)	$ (20.9)	$ 103.3	$ 1.6	$ 29.3
Increase (Decrease) in Stockholders' Equity
Issuance of ordinary shares (in shares)			0.2
Repurchase of ordinary shares/common stock (in shares)			(13.5)
Repurchase of ordinary shares/common stock	(180.5)			(180.5)			(180.5)
Capital contributions (redemptions)	0.0	$ (0.4)							0.0
Equity-based compensation	3.2			3.2			3.2
Foreign currency translation adjustment	0.5					0.5	0.5
Amortization related to derivative securities, net of tax	0.6					0.6	0.6
Other changes in non-controlling interests	0.2							0.2
Dividends	(9.2)				(9.2)		(9.2)
Net income (loss)	59.4				52.7		52.7		6.7
Ending balance (in shares) at Mar. 31, 2019			91.9
Ending balance at Mar. 31, 2019	8.4		$ 0.1	587.3	(597.0)	(19.8)	(29.4)	1.8	36.0
Beginning balance at Dec. 31, 2018		41.9
Increase (Decrease) in redeemable non-controlling interest in consolidated Funds
Net income (loss)		1.7
Ending balance at Mar. 31, 2019		43.2
Beginning balance at Dec. 31, 2018	176.1
Increase (Decrease) in total equity and redeemable non-controlling interest in consolidated Funds
Issuance of ordinary shares/common stock	0.0
Repurchase of common stock	(180.5)
Capital contributions (redemptions)	(0.4)
Equity-based compensation	3.2
Foreign currency translation adjustment	0.5
Amortization related to derivative securities, net of tax	0.6
Dividends	(9.2)
Net income (loss)	61.1
Ending balance at Mar. 31, 2019	51.6
Beginning balance (in shares) at Dec. 31, 2019			85.9
Beginning balance at Dec. 31, 2019	114.5		$ 0.1	534.3	(452.5)	(17.5)	64.4	1.3	48.8
Increase (Decrease) in Stockholders' Equity
Retirement of common stock (in shares)			(0.2)
Repurchase of ordinary shares/common stock (in shares)			(3.2)
Repurchase of ordinary shares/common stock	(19.2)			(19.2)			(19.2)
Capital contributions (redemptions)	0.2	1.2							0.2
Equity-based compensation	1.1			1.1			1.1
Foreign currency translation adjustment	(2.1)					(2.1)	(2.1)
Amortization related to derivative securities, net of tax	0.5					0.5	0.5
Dividends	(8.4)				(8.4)		(8.4)
Net income (loss)	32.7						32.6		0.1
Ending balance (in shares) at Mar. 31, 2020			82.5
Ending balance at Mar. 31, 2020	119.3		$ 0.1	$ 516.2	$ (428.3)	$ (19.1)	$ 68.9	$ 1.3	$ 49.1
Beginning balance at Dec. 31, 2019		83.9
Increase (Decrease) in redeemable non-controlling interest in consolidated Funds
Net income (loss)		(10.6)
Ending balance at Mar. 31, 2020		$ 74.5
Beginning balance at Dec. 31, 2019	198.4
Increase (Decrease) in total equity and redeemable non-controlling interest in consolidated Funds
Repurchase of common stock	(19.2)
Capital contributions (redemptions)	1.4
Equity-based compensation	1.1
Foreign currency translation adjustment	(2.1)
Amortization related to derivative securities, net of tax	0.5
Dividends	(8.4)
Net income (loss)	22.1
Ending balance at Mar. 31, 2020	$ 193.8