Investments TV Food Network (Details) - Television Food Network, G.P. - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Schedule of Equity Method Investments [Line Items]
Revenues, net	$ 307,945	$ 297,356
Operating income	162,756	192,682
Net income	$ 165,589	$ 159,461