Earnings (Loss) Per Share - Summary (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended		3 Months Ended								12 Months Ended
	Feb. 07, 2019	[1]	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	[1]	Dec. 31, 2018
Earnings Per Share [Abstract]
Net income (loss) attributable to Dun & Bradstreet Holdings, Inc. (Successor) / The Dun & Bradstreet Corporation (Predecessor)	$ (75.6)		$ 7.0	$ (17.0)	$ (207.1)	$ 41.5	$ (263.3)	$ (88.8)	$ (94.0)	$ (227.9)	$ (175.6)	$ (674.0)		$ 288.1
Weighted average number of shares outstanding - basic (shares)	37.2										367.1	314.5		37.1
Weighted average number of shares outstanding - diluted (shares)	37.2										367.1	314.5		37.3
Earnings (loss) per share of common stock:
Basic (USD per share)	$ (2.04)										$ (0.48)	$ (2.14)		$ 7.76
Diluted (USD per share)	$ (2.04)										$ (0.48)	$ (2.14)		$ 7.72

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