Condensed Consolidated Statements of Equity - USD ($) $ in Millions		Total		Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit/Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]	Redeemable Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)				153,200,000				3,900,000
Cumulative effect of new accounting principle | Accounting Standards Update 2018-02 [Member]						$ (1.0)	$ 1.0
Beginning balance, adjusted		$ 1,786.5			$ 1,585.8	380.1	1.3	$ (180.7)
Beginning balance at Dec. 31, 2018		1,786.5			1,585.8	381.1	0.3	$ (180.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)				153,100,000				3,500,000
Grant of restricted shares of common stock (in shares)								(800,000)
Grant of restricted shares of common stock					(37.3)			$ 37.3
Forfeitures of restricted shares of common stock					2.9			$ (2.9)
Forfeitures of restricted shares of common stock (shares)								100,000
Tax withholding payments for restricted share vesting (in shares)				100,000
Tax withholding payments for restricted share vesting		$ (15.9)			(15.9)
Vesting of restricted shares granted from treasury stock					6.7			$ (6.7)
Vesting of restricted shares granted from treasury (in shares)								100,000
Stock Repurchased During Period, Shares		200,000						200,000
Stock Repurchased During Period, Value		$ (11.9)						$ (11.9)
Equity-based compensation expense		39.8			39.8
Net earnings (loss)		95.9				95.9
Net losses attributable to redeemable noncontrolling interests		0.0
Equity-based compensation expense of unconsolidated affiliates		1.1				1.1
Foreign currency translation adjustment	[1]	0.0
Unrealized gains on interest rate swaps, net		(21.9)					(21.9)
Unrealized loss on investments in unconsolidated affiliates		(5.8)	[2]				(5.8)
Ending balance at Sep. 30, 2019		1,867.8			1,582.0	477.1	(26.4)	$ (164.9)
Ending balance (in shares) at Sep. 30, 2019				153,100,000				3,500,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)				153,100,000				3,400,000
Beginning balance at Jun. 30, 2019		1,825.6			1,567.3	439.3	(20.1)	$ (160.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)				153,100,000				3,500,000
Forfeitures of restricted shares of common stock					1.9			$ (1.9)
Forfeitures of restricted shares of common stock (shares)								100,000
Tax withholding payments for restricted share vesting (in shares)				0
Tax withholding payments for restricted share vesting		(3.7)			(3.7)
Vesting of restricted shares granted from treasury stock					2.1			$ (2.1)
Vesting of restricted shares granted from treasury (in shares)								0
Equity-based compensation expense		14.4			14.4
Net earnings (loss)		37.3				37.3
Net losses attributable to redeemable noncontrolling interests		0.0
Equity-based compensation expense of unconsolidated affiliates		0.5				0.5
Foreign currency translation adjustment	[1]	0.0
Unrealized gains on interest rate swaps, net		(2.9)					(2.9)
Unrealized loss on investments in unconsolidated affiliates		(3.4)	[2]				(3.4)
Ending balance at Sep. 30, 2019		1,867.8			1,582.0	477.1	(26.4)	$ (164.9)
Ending balance (in shares) at Sep. 30, 2019				153,100,000				3,500,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)				153,100,000				3,500,000
Beginning balance (in shares)				153,100,000				3,400,000
Cumulative effect of new accounting principle		(1.1)
Cumulative effect of new accounting principle | Accounting Standards Update 2016-13 [Member]						(1.1)
Beginning balance, adjusted		1,897.4			1,586.8	489.5	(20.2)	$ (158.7)	$ 0.0
Beginning balance at Dec. 31, 2019		1,898.5			1,586.8	490.6	(20.2)	$ (158.7)	0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)				160,100,000				3,100,000
Issuance of common stock, net of underwriters' discount and issuance costs (shares)				7,100,000
Issuance of common stock, net of underwriters' discount and issuance costs		$ 484.2			484.2
Grant of restricted shares of common stock (in shares)								(500,000)
Grant of restricted shares of common stock					(24.8)			$ 24.8
Forfeitures of restricted shares of common stock					0.5			$ 0.5
Tax withholding payments for restricted share vesting (in shares)		100,000						0
Tax withholding payments for restricted share vesting		$ (20.9)			(20.9)
Vesting of restricted shares granted from treasury stock					9.5			$ (9.5)
Vesting of restricted shares granted from treasury (in shares)								200,000
Fair value adjustment to redeemable noncontrolling interests		$ (1.9)			(1.9)				0.0
Stock Repurchased During Period, Shares		0
Equity-based compensation expense		$ 29.4			29.4
Contributions received for redeemable noncontrolling interests in Optimal Blue Holdco, LLC									578.0
Fair value adjustment to redeemable noncontrolling interests		(13.2)			(13.2)				13.2
Net earnings (loss)		217.0				217.0
Net losses attributable to redeemable noncontrolling interests		13.2							(13.2)
Equity-based compensation expense of unconsolidated affiliates		3.2				3.2
Foreign currency translation adjustment		(0.1)	[1]				(0.1)
Unrealized gains on interest rate swaps, net		(15.8)					(15.8)
Unrealized loss on investments in unconsolidated affiliates		3.0	[2]				3.0
Ending balance at Sep. 30, 2020		2,582.3			2,049.6	709.7	(33.1)	$ (143.9)	578.0
Ending balance (in shares) at Sep. 30, 2020				160,100,000				3,100,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)				160,100,000				3,000,000.0
Beginning balance at Jun. 30, 2020		2,453.2			2,055.9	582.3	(41.9)	$ (143.1)	0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)				160,100,000				3,100,000
Grant of restricted shares of common stock (in shares)								0
Grant of restricted shares of common stock					(0.2)			$ 0.2
Forfeitures of restricted shares of common stock					0.2			(0.2)
Tax withholding payments for restricted share vesting (in shares)				0
Tax withholding payments for restricted share vesting		(1.2)			(1.2)
Vesting of restricted shares granted from treasury stock					0.8			$ (0.8)
Vesting of restricted shares granted from treasury (in shares)								100,000
Fair value adjustment to redeemable noncontrolling interests		(1.9)			(1.9)				0.0
Equity-based compensation expense		9.2			9.2
Contributions received for redeemable noncontrolling interests in Optimal Blue Holdco, LLC									578.0
Fair value adjustment to redeemable noncontrolling interests		(13.2)			(13.2)				13.2
Net earnings (loss)		127.8				127.8
Net losses attributable to redeemable noncontrolling interests		13.2							(13.2)
Equity-based compensation expense of unconsolidated affiliates		(0.4)				(0.4)
Foreign currency translation adjustment		0.1	[1]				0.1
Unrealized gains on interest rate swaps, net		4.0					4.0
Unrealized loss on investments in unconsolidated affiliates		4.7	[2]				4.7
Ending balance at Sep. 30, 2020		$ 2,582.3			$ 2,049.6	$ 709.7	$ (33.1)	$ (143.9)	$ 578.0
Ending balance (in shares) at Sep. 30, 2020				160,100,000				3,100,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)				160,100,000				3,100,000

[1] Net of income tax expense of less than $0.1 million and income tax benefit of less than $0.1 million for the three and nine months ended September 30, 2020, respectively.

[2] Net of income tax expense of $1.6 million and $1.0 million for the three and nine months ended September 30, 2020, respectively, and income tax benefit of $1.1 million and $2.0 million for the three and nine months ended September 30, 2019, respectively.