Contingent Liabilities (Details) carrier in Thousands, $ in Millions				1 Months Ended	78 Months Ended
	Aug. 12, 2020 USD ($) carrier plaintiff	Feb. 27, 2020 USD ($)	May 25, 2017 USD ($)	Feb. 29, 2020 USD ($)	May 31, 2016 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	May 01, 2019 USD ($)
YP Acquisition
Loss Contingencies [Line Items]
Value of escrowed stock						$ 25.9	$ 29.8
Walker v. Directory Distributing Associates, Inc. et al. | Judicial Ruling
Loss Contingencies [Line Items]
Number of plaintiffs | plaintiff	2,500
Maximum exposure								$ 1.5
Number of former carriers | carrier	46
Contingent liability	$ 0.8
Krawczyk V. Directory Distributing Associates, Inc. Et Al | Judicial Ruling
Loss Contingencies [Line Items]
Maximum exposure								$ 1.5
Number of former carriers | carrier	46
Contingent liability	$ 0.8
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						1.9
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						33.7	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						0.7	$ 7.1
Texas Comptroller
Loss Contingencies [Line Items]
Sales and excise tax payable						$ 2.4