Contingent Liabilities (Details) - USD ($) $ in Millions				1 Months Ended
	Feb. 27, 2020	Jan. 17, 2019	May 25, 2017	Jan. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
YP Acquisition
Loss Contingencies [Line Items]
Value of escrowed stock					$ 24.3	$ 29.8
New York State Division of Taxation and Finance
Loss Contingencies [Line Items]
Tax and interest due		$ 8.7
Unpaid tax and interest balance					3.5
Sales and excise tax payable					2.7
New York State Division of Taxation and Finance | Subsequent Event
Loss Contingencies [Line Items]
Payment of tax and interest				$ 3.5
New York State Division of Taxation and Finance | First Case | December 1, 2009 Through Tax Year May 31, 2012
Loss Contingencies [Line Items]
Tax and interest due			$ 3.2
Payment of tax and interest		$ 5.1
New York State Division of Taxation and Finance | Second Case | June 1, 2012 Through Tax Year May 31, 2016
Loss Contingencies [Line Items]
Tax and interest due	$ 3.3
IRS | Section 199 Tax Case
Loss Contingencies [Line Items]
Reserve in connection with disallowance					31.9	46.0
Amount to be paid before allowance of tax credit					8.0
IRS | Research and Development Tax Case
Loss Contingencies [Line Items]
Reserve in connection with disallowance					0.2	$ 7.1
Texas Comptroller
Loss Contingencies [Line Items]
Sales and excise tax payable					$ 2.7