Segment Information - Summarized Financial Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information [Line Items]
Revenues	$ 394.5	$ 361.3	$ 781.7	$ 711.0
Operating expenses	216.8	197.0	424.7	383.2
Transition and integration costs	8.2	4.3	15.8	12.2
EBITDA	169.5	160.0	341.2	315.6
Depreciation and amortization	92.5	90.4	184.0	178.2
Operating income	77.0	69.6	157.2	137.4
Interest expense, net	(22.6)	(20.9)	(43.7)	(41.2)
Other expense, net	(2.4)	(1.0)	(3.6)	(4.2)
Earnings before income taxes and equity in (losses) earnings of unconsolidated affiliates	52.0	47.7	109.9	92.0
Income tax expense	11.6	10.5	10.5	15.7
Earnings before equity in (losses) earnings of unconsolidated affiliates	40.4	37.2	99.4	76.3
Equity in earnings (losses) of unconsolidated affiliates, net of tax	(0.1)	(5.0)	303.0	1.4
Net earnings	40.3	32.2	402.4	77.7
Net losses attributable to redeemable noncontrolling interests		7.5	2.5	16.1
Net earnings attributable to Black Knight	40.3	39.7	404.9	93.8
Allocated share-based compensation expense	10.8	10.9	19.3	18.1
Operating Segments | Software Solutions
Segment Reporting Information [Line Items]
Revenues	339.4	305.4		601.2
Operating expenses	148.7	130.6		255.5
EBITDA	190.7	174.8		345.7
Depreciation and amortization	35.9	33.2		64.4
Operating income	154.8	141.6		281.3
Operating Segments | Data and Analytics
Segment Reporting Information [Line Items]
Revenues	55.1	55.9		109.8
Operating expenses	37.4	35.1		69.3
EBITDA	17.7	20.8		40.5
Depreciation and amortization	4.0	3.7		7.5
Operating income	13.7	17.1		33.0
Corporate and Other
Segment Reporting Information [Line Items]
Operating expenses	30.7	31.3	58.6	58.4
Transition and integration costs	8.2	4.3	15.8	12.2
EBITDA	(38.9)	(35.6)	(74.4)	(70.6)
Depreciation and amortization	52.6	53.5	105.2	106.3
Operating income	(91.5)	(89.1)	(179.6)	(176.9)
Allocated share-based compensation expense	$ 13.0	$ 13.2	24.2	$ 23.7
Corporate and Other | Software Solutions
Segment Reporting Information [Line Items]
Revenues			670.1
Operating expenses			291.2
EBITDA			378.9
Depreciation and amortization			71.0
Operating income			307.9
Corporate and Other | Data and Analytics
Segment Reporting Information [Line Items]
Revenues			111.6
Operating expenses			74.9
EBITDA			36.7
Depreciation and amortization			7.8
Operating income			$ 28.9