Consolidated and Combined Statements of Equity - USD ($) shares in Millions, $ in Millions		Total		Common Class A	Accumulated deficit/retained earnings	Accumulated other comprehensive loss	Treasury Stock [Member]	Common stock	Additional paid-in capital	Noncontrolling interests	Black Knight Financial Services, Inc. Common stock Common Class A	Black Knight Financial Services, Inc. Common stock Common Class B
Beginning balance at Dec. 31, 2015		$ 1,845.0			$ 19.9	$ (0.1)	$ 0.0		$ 798.9	$ 1,026.3
Beginning balance (shares) at Dec. 31, 2015							0.0	0.0			68.3	84.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)											0.8
Equity based compensation expense		11.9							11.9
Unrealized gains on interest rate swaps, net		(1.8)				(0.6)				(1.2)
Tax distributions to members		(48.6)								(48.6)
Net earnings		133.0			45.8					87.2
Foreign currency translation adjustment, net of tax (3)		(0.1)	[1]			(0.1)
Ending balance at Dec. 31, 2016		1,939.4			65.7	(0.8)			810.8	1,063.7
Ending balance (shares) at Dec. 31, 2016								0.0			69.1	84.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)											1.0
Equity based compensation expense		18.7							18.7
Unrealized gains on interest rate swaps, net		6.3				4.1				2.2
Tax distributions to members		(75.3)								(75.3)
Forfeitures of restricted shares of Class A common stock (shares)											(0.1)
Exchange of Class B common stock for Class A common stock											0.2	(0.2)
Tax withholding payments for restricted share vesting (shares)								(0.1)			(0.1)
Tax withholding payments for restricted share vesting		(6.1)							(6.1)
Purchases of treasury stock (share)							3.2
Purchases of treasury stock		(136.7)					$ (136.7)
Distribution of FNF's ownership interest and related transactions		(291.7)			(46.6)	0.6	$ 46.6		770.2	(1,062.5)
Distribution of FNF's ownership interest and related transactions (shares)							(1.2)	153.5			(70.1)	(84.6)
Net earnings		254.2			182.3					71.9
Foreign currency translation adjustment, net of tax (3)	[1]	0.0
Ending balance at Dec. 31, 2017		1,708.8			201.4	3.9	$ (90.1)		1,593.6	0.0
Ending balance (shares) at Dec. 31, 2017							2.0	153.4			0.0	0.0
Beginning balance at Dec. 31, 2016		1,939.4			65.7	(0.8)			810.8	1,063.7
Beginning balance (shares) at Dec. 31, 2016								0.0			69.1	84.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Purchases of treasury stock (share)				1.2
Purchases of treasury stock		(278.2)
Ending balance at Dec. 31, 2018		1,786.5			381.1	0.3	$ (180.7)		1,585.8	0.0
Ending balance (shares) at Dec. 31, 2018							3.9	153.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
After-tax adjustment		11.2			11.2
Adjusted balance		1,720.0			212.6	3.9	$ (90.1)		1,593.6
Beginning balance at Dec. 31, 2017		1,708.8			201.4	3.9	$ (90.1)		1,593.6	0.0
Beginning balance (shares) at Dec. 31, 2017							2.0	153.4			0.0	0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Grant of restricted shares of common stock							$ 52.2		(52.2)
Forfeitures of restricted shares of common stock							$ (0.6)		0.6
Issuance of restricted shares of Class A common stock (shares)							(1.1)
Equity based compensation expense		50.7							50.7
Unrealized gains on interest rate swaps, net		(3.4)				(3.4)				0.0
Tax withholding payments for restricted share vesting (shares)								(0.2)
Tax withholding payments for restricted share vesting		(9.4)					$ 0.0		(9.4)
Adjustments to Additional Paid in Capital, Share-based Compensation, Restricted Stock Unit or Restricted Stock Award, Requisite Service Period Recognition							$ (0.7)		0.7
Purchases of treasury stock (share)				0.0			3.0
Purchases of treasury stock		(141.5)					$ (141.5)
Net earnings		168.5			168.5					0.0
Foreign currency translation adjustment, net of tax (3)		(0.2)	[1]			(0.2)
Adjustments To Additional Paid In Capital Tax Distribution		1.8							1.8
Ending balance at Dec. 31, 2018		$ 1,786.5			$ 381.1	$ 0.3	$ (180.7)		$ 1,585.8	$ 0.0
Ending balance (shares) at Dec. 31, 2018							3.9	153.2

[1] Net of income tax benefit of $0.1 million for the year ended December 31, 2018.