Investments Career Builder, Dose Media and CV Summarized Financial Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
CareerBuilder, LLC and Dose Media, LLC
Schedule of Equity Method Investments [Line Items]
Revenues, net	$ 645,790	$ 719,994	[1]	$ 698,041
Operating income	(7,324)	93,619	[1]	84,199
Net income	(16,845)	89,249	[1]	$ 80,280
Current assets	181,812	222,563
Non-current assets	486,750	565,200
Current liabilities	192,388	205,643
Non-current liabilities	320,727	23,603
Redeemable non-controlling interest	$ 36,661	$ 46,265
Dose Media, LLC
Schedule of Equity Method Investments [Line Items]
Ownership in equity method investment, percent	25.00%

[1] (1)On November 25, 2015, the Company acquired a 25% interest in Dose Media. As results of operations from date of acquisition are not material to the Company in 2015, they are not included in the above table for 2015.