Take-Private Transaction - Pro Forma Information (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
Business Acquisition [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
Pro forma revenue	181.6											1,427.4		1,736.7
Pro forma adjustments - net of tax effect
Pro forma net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor)	(77.0)											(692.9)		267.4
Deferred revenue fair value adjustment
Business Acquisition [Line Items]
Revenue	$ 0.0											2.4		(4.8)
Dun & Bradstreet
Business Acquisition [Line Items]
Revenue												178.7		1,716.4
Reported net income (loss) attributable to Dun & Bradstreet Holdings, Inc.(Successor)												(75.6)		288.1
Take Private Acquisition, Dun & Bradstreet
Business Acquisition [Line Items]
Revenue												1,413.9		0.0
Pro forma revenue												1,726.9		1,564.2
Reported net income (loss) attributable to Dun & Bradstreet Holdings, Inc.(Successor)												(674.0)		0.0
Pro forma adjustments - net of tax effect
Pro forma net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor)												(473.9)		(583.7)
Take Private Acquisition, Dun & Bradstreet | Deferred revenue fair value adjustment
Business Acquisition [Line Items]
Revenue												134.3		(152.2)
Pro forma adjustments - net of tax effect
Pro forma net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor)												104.4		(118.3)
Take Private Acquisition, Dun & Bradstreet | Incremental amortization of intangibles
Pro forma adjustments - net of tax effect
Pro forma net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor)												(15.5)		(350.7)
Take Private Acquisition, Dun & Bradstreet | Amortization of deferred commissions
Pro forma adjustments - net of tax effect
Pro forma net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor)												(2.0)		16.9
Take Private Acquisition, Dun & Bradstreet | Transaction costs
Pro forma adjustments - net of tax effect
Pro forma net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor)												154.9		(114.5)
Take Private Acquisition, Dun & Bradstreet | Pension expense adjustment
Pro forma adjustments - net of tax effect
Pro forma net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor)												69.5		38.9
Take Private Acquisition, Dun & Bradstreet | Equity-based compensation adjustment
Pro forma adjustments - net of tax effect
Pro forma net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor)												8.1		0.0
Take Private Acquisition, Dun & Bradstreet | Preferred dividend adjustment
Pro forma adjustments - net of tax effect
Pro forma net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor)												(21.8)		(128.7)
Take Private Acquisition, Dun & Bradstreet | Incremental interest expense and facility cost adjustment
Pro forma adjustments - net of tax effect
Pro forma net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor)												$ (21.9)		$ (215.4)

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