Fair Value Measurements (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Measured on a recurring basis | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, net	$ 0.0	$ 0.0
Measured on a recurring basis | Level 1 | DiscoverOrg Holdings
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, net		0.0	$ 0.0
Measured on a recurring basis | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, net	(13.1)	(6.0)
Measured on a recurring basis | Level 2 | DiscoverOrg Holdings
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, net		(6.0)	0.0
Measured on a recurring basis | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, net	$ 0.0	0.0
Measured on a recurring basis | Level 3 | DiscoverOrg Holdings
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract, net		0.0	0.0
Measured on a non-recurring basis | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired right-of-use assets		0.0
Measured on a non-recurring basis | Level 1 | DiscoverOrg Holdings
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired right-of-use assets		0.0	0.0
Measured on a non-recurring basis | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired right-of-use assets		0.0
Measured on a non-recurring basis | Level 2 | DiscoverOrg Holdings
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired right-of-use assets		0.0	0.0
Measured on a non-recurring basis | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired right-of-use assets		1.4
Measured on a non-recurring basis | Level 3 | DiscoverOrg Holdings
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired right-of-use assets		$ 1.4	$ 0.0