Earnings (Loss) Per Share - Summary (Details) - USD ($) $ / shares in Units, shares in Millions, $ 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
Earnings Per Share [Abstract]
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)
Weighted average number of shares outstanding - basic (shares)	[1]	37.2	415.7	314.5	348.5	314.5
Weighted average number of shares outstanding - diluted (shares)	[1]	37.2	415.7	314.5	348.5	314.5
Earnings (loss) per share of common stock:
Basic (USD per share)	[1]	$ (2.04)	$ (0.04)	$ (0.28)	$ (0.52)	$ (1.31)
Diluted (USD per share)	[1]	$ (2.04)	$ (0.04)	$ (0.28)	$ (0.52)	$ (1.31)

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