Acquisitions - Pro Forma Information (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
Business Acquisition [Line Items]
Revenue	[1]	$ 178.7	$ 442.1	$ 408.2	$ 1,258.0	$ 981.2
Pro forma revenue		181.6		409.4		993.5
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)
Pro forma net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor) / The Dun & Bradstreet Corporation (Predecessor)		(77.0)		$ (87.5)		$ (430.5)
Blended statutory tax rate (as a percent)				22.30%		22.30%
Pre-acquisition net loss
Business Acquisition [Line Items]
Net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor) / The Dun & Bradstreet Corporation (Predecessor)		(1.0)		$ 0.0		$ (19.7)
Intangible amortization - net of tax benefits
Business Acquisition [Line Items]
Net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor) / The Dun & Bradstreet Corporation (Predecessor)		(0.4)		0.0		(1.4)
Deferred revenue fair value adjustment
Business Acquisition [Line Items]
Revenue		0.0		1.2		1.2
Net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor) / The Dun & Bradstreet Corporation (Predecessor)		0.0		0.9		0.9
Transaction costs
Business Acquisition [Line Items]
Net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor) / The Dun & Bradstreet Corporation (Predecessor)		0.0		0.4		0.4
Lattice
Business Acquisition [Line Items]
Revenue		$ 2.9		$ 0.0		$ 11.1

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