Take-Private Transaction - Purchase Price Allocation (Details) - USD ($) $ in Millions	11 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Feb. 08, 2019	Feb. 07, 2019	Dec. 31, 2018
Purchase Price Allocation:
Goodwill	$ 2,840.1	$ 2,856.2	$ 2,840.1		$ 773.5	$ 770.8
Take Private Acquisition, Dun & Bradstreet
Business Acquisition [Line Items]
Weighted Average Amortization Period (years)		16 years 6 months
Purchase Price Allocation:
Cash	117.7		117.7	$ 117.7
Accounts receivable	266.1		266.1	267.8
Other	46.4		46.4	46.8
Total current assets	430.2		430.2	432.3
Goodwill	2,787.6		2,787.6	2,797.6
Property, plant & equipment	30.3		30.3	30.3
Right of use asset	111.3		111.3	103.9
Other	34.3		34.3	34.4
Total assets acquired	9,386.3		9,386.3	9,333.3
Accounts payable	74.2		74.2	74.2
Deferred revenue	397.8		397.8	398.4
Accrued liabilities	237.8		237.8	240.1
Short-term pension and other accrued benefits	106.0		106.0	106.0
Other current liabilities	45.8		45.8	41.1
Total current liabilities	861.6		861.6	859.8
Long-term pension and postretirement obligations	221.0		221.0	213.6
Deferred tax liability	1,380.6		1,380.6	1,388.3
Long-term debt	625.1		625.1	625.1
Other liabilities	169.0		169.0	161.0
Total liabilities assumed	3,257.3		3,257.3	3,247.8
Non-controlling interest	60.3		60.3	16.8
Less: debt repayment	637.5		637.5	637.5
Amounts paid to equity holders	5,431.2		5,431.2	5,431.2
Measurement Period Adjustments
Accounts receivable	(1.7)
Other	(0.4)
Total current assets	(2.1)
Goodwill	(10.0)		(10.0)
Right of use asset	7.4
Other	(0.1)
Total assets acquired	53.0
Deferred revenue	(0.6)
Accrued liabilities	(2.3)
Other current liabilities	4.7
Total current liabilities	1.8
Long-term pension and postretirement obligations	7.4
Deferred tax liability	(7.7)
Other liabilities	8.0
Total liabilities assumed	9.5
Non-controlling interest	43.5
Take Private Acquisition, Dun & Bradstreet | Trademark
Purchase Price Allocation:
Intangible assets	1,275.8		1,275.8	1,200.8
Measurement Period Adjustments
Intangible assets	75.0
Take Private Acquisition, Dun & Bradstreet | Customer relationships
Business Acquisition [Line Items]
Weighted Average Amortization Period (years)		16 years 10 months 24 days
Purchase Price Allocation:
Intangible assets	2,388.5		2,388.5	2,589.0
Measurement Period Adjustments
Intangible assets	(200.5)
Take Private Acquisition, Dun & Bradstreet | Partnership agreements
Business Acquisition [Line Items]
Weighted Average Amortization Period (years)		14 years 3 months 18 days
Purchase Price Allocation:
Intangible assets	230.3		230.3	0.0
Measurement Period Adjustments
Intangible assets	230.3
Take Private Acquisition, Dun & Bradstreet | Computer software
Business Acquisition [Line Items]
Weighted Average Amortization Period (years)		7 years 9 months 18 days
Purchase Price Allocation:
Intangible assets	376.0		376.0	376.0
Take Private Acquisition, Dun & Bradstreet | Database
Business Acquisition [Line Items]
Weighted Average Amortization Period (years)		17 years
Purchase Price Allocation:
Intangible assets	1,722.0		$ 1,722.0	$ 1,769.0
Measurement Period Adjustments
Intangible assets	$ (47.0)