Investments TV Food Network (Details) - Television Food Network, G.P. - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Schedule of Equity Method Investments [Line Items]
Revenues, net	$ 294,308	$ 274,754	$ 924,407	$ 880,868
Operating income (loss)	139,679	157,207	474,223	547,363
Net income	$ 142,903	$ 123,009	$ 484,781	$ 447,348