Segment Information - Summary (Details) - USD ($) $ in Millions	1 Months Ended		3 Months Ended								12 Months Ended
	Feb. 07, 2019		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019		Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenue	$ 178.7	[1]	$ 480.1	$ 442.1	$ 420.6	$ 395.3	$ 432.7	$ 408.2	$ 398.9	$ 174.1	$ 1,738.1	$ 1,413.9	[1]	$ 1,716.4
Adjusted EBITDA	66.3										715.4	502.1		568.6
Depreciation and amortization	(11.1)	[1]									(536.9)	(482.4)	[1]	(88.7)
Interest expense - net	(5.2)										(270.3)	(301.1)		(52.5)
Dividends allocated to preferred stockholders	0.0	[1]									(64.1)	(114.0)	[1]	0.0
Benefit (provision) for income taxes	27.5	[1]									110.5	118.2	[1]	(81.6)
Other income (expense) - net	(86.0)	[1]									(12.0)	(154.8)	[1]	(3.3)
Equity in net income of affiliates	0.5	[1]									2.3	4.2	[1]	2.8
Net income (loss) attributable to non-controlling interest	(0.8)	[1]	(1.3)	(2.1)	(1.2)	(0.4)	(3.2)	(1.4)	(1.5)	(0.4)	(5.0)	(6.5)	[1]	(6.2)
Lag adjustment	(2.7)										0.0	0.0		0.0
Other incremental or reduced expenses from the application of purchase accounting	0.0										18.8	20.7		0.0
Equity-based compensation	(11.7)										(45.1)	(11.7)		(10.8)
Restructuring charges	(0.1)	[1]									(34.8)	(51.8)	[1]	(25.4)
Merger and acquisition-related operating costs	(52.0)										(14.1)	(156.0)		(11.6)
Transition costs	(0.3)										(31.9)	(37.7)		(0.3)
Legal expense associated with significant legal and regulatory matters	0.0										(3.9)	0.2		(2.9)
Asset impairment	0.0										(4.5)	(3.4)		0.0
Net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor) / The Dun & Bradstreet Corporation (Predecessor)	(75.6)	[1]	$ 7.0	$ (17.0)	$ (207.1)	$ 41.5	$ (263.3)	$ (88.8)	$ (94.0)	$ (227.9)	(175.6)	(674.0)	[1]	288.1
Deferred revenue purchase accounting adjustments	(2.7)										21.1	138.9
Capital expenditures	0.2										7.7	12.5		5.1
Additions to computer software and other intangibles	5.1										113.7	56.4		53.1
Operating Segments
Segment Reporting Information [Line Items]
Depreciation and amortization	(7.3)										(53.8)	(40.7)		(49.8)
Capital expenditures	0.3										7.5	11.5		4.3
Additions to computer software and other intangibles	5.1										112.3	54.4		44.4
Corporate and other
Segment Reporting Information [Line Items]
Revenue	(25.9)										(21.1)	(138.9)		0.0
Adjusted EBITDA	(9.3)										(75.8)	(210.7)		(98.5)
Depreciation and amortization	(3.8)										(483.1)	(441.7)		(38.9)
Capital expenditures	(0.1)										0.2	1.0		0.8
Additions to computer software and other intangibles	0.0										1.4	2.0		8.7
North America | Operating Segments
Segment Reporting Information [Line Items]
Revenue	148.2										1,459.9	1,316.5		1,420.6
Adjusted EBITDA	55.3										696.4	634.6		575.9
Depreciation and amortization	(5.8)										(45.9)	(34.8)		(41.3)
Capital expenditures	0.2										1.9	9.6		3.6
Additions to computer software and other intangibles	4.3										106.2	48.0		39.5
International | Operating Segments
Segment Reporting Information [Line Items]
Revenue	56.4										299.3	236.3		295.8
Adjusted EBITDA	20.3										94.8	78.2		91.2
Depreciation and amortization	(1.5)										(7.9)	(5.9)		(8.5)
Capital expenditures	0.1										5.6	1.9		0.7
Additions to computer software and other intangibles	$ 0.8										$ 6.1	$ 6.4		$ 4.9

[1] See Note 1 "Basis of Presentation" for further discussion.