Segment Information - Summary (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended		9 Months Ended
		Feb. 07, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Revenue	[1]	$ 178.7	$ 442.1	$ 408.2	$ 1,258.0	$ 981.2
Adjusted EBITDA		66.3	197.0	155.0	506.5	344.1
Depreciation and amortization	[1]	(11.1)	(134.1)	(123.3)	(401.0)	(340.6)
Interest expense - net		(5.2)	(60.6)	(85.1)	(221.1)	(218.5)
Dividends allocated to preferred stockholders	[1]	0.0	0.0	(32.1)	(64.1)	(82.0)
Benefit for income taxes - net	[1]	27.5	9.3	24.0	111.1	84.1
Other income (expense) - net	[1]	(86.0)	(9.5)	6.3	(42.2)	18.6
Equity in net income of affiliates	[1]	0.5	0.7	0.5	1.9	3.4
Net income (loss) attributable to non-controlling interest	[1]	(0.8)	(2.1)	(1.4)	(3.7)	(3.3)
Lag adjustment		(2.7)	0.0	0.0	0.0	0.0
Other incremental or reduced expenses from the application of purchase accounting		0.0	4.5	5.3	14.4	15.9
Equity-based compensation		(11.7)	(9.7)	(3.6)	(38.6)	(7.9)
Restructuring charges	[1]	(0.1)	(4.9)	(8.2)	(16.2)	(44.1)
Merger and acquisition-related operating costs		(52.0)	(2.2)	(5.9)	(6.7)	(154.5)
Transition costs		(0.3)	(5.1)	(20.3)	(22.3)	(23.8)
Legal reserve associated with significant legal and regulatory matters		0.0	0.0	0.0	0.0	0.2
Asset impairment		0.0	(0.3)	0.0	(0.6)	(2.3)
Net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor) / The Dun & Bradstreet Corporation (Predecessor)	[1]	(75.6)	(17.0)	(88.8)	(182.6)	(410.7)
Deferred revenue purchase accounting adjustments		(2.7)	(1.0)	(39.2)	(20.5)	(99.3)
Capital expenditures		0.2	4.5	2.1	7.8	9.0
Additions to computer software and other intangibles		5.1	35.6	19.2	81.6	40.1
Operating Segments
Segment Reporting Information [Line Items]
Depreciation and amortization		(7.3)	(13.9)	(12.0)	(39.3)	(29.5)
Capital expenditures		0.3	4.4	1.8	7.5	8.3
Additions to computer software and other intangibles		5.1	33.4	18.3	75.5	38.4
Corporate and other
Segment Reporting Information [Line Items]
Revenue		(25.9)	(1.0)	(39.2)	(20.5)	(99.3)
Adjusted EBITDA		(9.3)	(15.4)	(60.1)	(63.2)	(147.8)
Depreciation and amortization		(3.8)	(120.2)	(111.3)	(361.7)	(311.1)
Capital expenditures		(0.1)	0.1	0.3	0.3	0.7
Additions to computer software and other intangibles		0.0	2.2	0.9	6.1	1.7
North America | Operating Segments
Segment Reporting Information [Line Items]
Revenue		148.2	363.3	374.7	1,059.1	916.8
Adjusted EBITDA		55.3	184.2	189.6	498.1	435.8
Depreciation and amortization		(5.8)	(11.8)	(10.2)	(33.6)	(25.3)
Capital expenditures		0.2	1.8	1.2	3.1	7.3
Additions to computer software and other intangibles		4.3	31.7	15.9	71.5	33.7
International | Operating Segments
Segment Reporting Information [Line Items]
Revenue		56.4	79.8	72.7	219.4	163.7
Adjusted EBITDA		20.3	28.2	25.5	71.6	56.1
Depreciation and amortization		(1.5)	(2.1)	(1.8)	(5.7)	(4.2)
Capital expenditures		0.1	2.6	0.6	4.4	1.0
Additions to computer software and other intangibles		$ 0.8	$ 1.7	$ 2.4	$ 4.0	$ 4.7

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