Investments Cash Distributions from Equity Method Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Cash distributions from equity investments	$ 201,892	[1]	$ 170,527	$ 180,207	[1]
Distributions from equity investments, return on investment	3,768		$ 0	10,328
CareerBuilder, LLC
Schedule of Equity Method Investments [Line Items]
Distributions from equity investments, return on investment	$ 4,000			$ 10,000

[1] (1) Certain distributions received from CareerBuilder in 2017 and 2015 exceeded the Company’s share of CareerBuilder’s cumulative earnings. As a result, the Company determined that these distributions were a return of investment and, therefore, presented such distributions totaling $4 million in 2017 and $10 million in 2015 as an investing activity in the Company’s Consolidated Statements of Cash Flows for 2017 and 2015.