Consolidated Statements of Operations and Comprehensive Earnings (Loss) - USD ($) shares in Millions, $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenues		$ 1,114.0	$ 1,051.6	$ 1,026.0
Expenses:
Operating expenses		625.4	569.5	582.6
Depreciation and amortization		217.0	206.5	208.3
Transition and integration costs		6.6	13.1	2.3
Total expenses		849.0	789.1	793.2
Operating income		265.0	262.5	232.8
Other income and expense:
Interest expense, net		(51.7)	(57.5)	(67.6)
Other expense, net		(7.1)	(12.6)	(6.4)
Total other expense, net		(58.8)	(70.1)	(74.0)
Earnings before income taxes		206.2	192.4	158.8
Income tax expense (benefit)		37.7	(61.8)	25.8
Net earnings from continuing operations		168.5	254.2	133.0
Net earnings		168.5	254.2	133.0
Less: Net earnings attributable to noncontrolling interests		0.0	71.9	87.2
Net earnings attributable to Black Knight		168.5	182.3	45.8
Other comprehensive (loss) earnings:
Unrealized holding (losses) gains, net of tax (1)	[1]	(0.7)	3.7	(1.1)
Reclassification adjustments for losses included in net earnings, net of tax	[2]	(2.7)	0.4	0.5
Total unrealized losses on interest rate swaps, net of tax		(3.4)	4.1	(0.6)
Foreign currency translation adjustment, net of tax (3)	[3]	(0.2)	0.0	(0.1)
Other comprehensive (loss) earnings		(3.6)	4.1	(0.7)
Comprehensive earnings attributable to noncontrolling interests		0.0	74.1	86.0
Comprehensive earnings		$ 164.9	$ 260.5	$ 131.1
Net earnings per share attributable to Black Knight common shareholders:
Basic (in dollars per share)		$ 1.14	$ 2.06	$ 0.69
Diluted (in dollars per share)		$ 1.14	$ 1.47	$ 0.67
Weighted average shares of Class A common stock outstanding
Basic (in shares)		147.6	88.7	65.9
Diluted (in shares)		148.2	152.4	67.9

[1] Net of income tax (benefit) expense of $(0.2) million, $2.1 million, and $(0.7) million for the years ended December 31, 2018, 2017 and 2016, respectively.

[2] Amounts reclassified to net earnings relate to (gains) losses on interest rate swaps and are included in Interest expense on the Consolidated Statements of Earnings and Comprehensive Earnings. Amount is net of income tax (benefit) expense of $(1.0) million, $0.3 million and $0.3 million for the years ended December 31, 2018, 2017 and 2016, respectively.

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