Employee Termination Programs - Summary of Rollforward of the Liability Related to the Reorganization (Details) - Reorganization [Member] - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost And Reserve [Line Items]
Liability, beginning balance		$ 3,540	$ 3,266
Net accruals		(103)	16,304
Payments		(3,437)	(14,202)
Non-cash	[1]		(1,828)
Liability, ending balance			3,540
U.S. Networks [Member]
Restructuring Cost And Reserve [Line Items]
Liability, beginning balance		1,955	3,258
Net accruals		(142)	10,539
Payments		(1,813)	(11,159)
Non-cash	[1]		(683)
Liability, ending balance			1,955
Corporate and Other [Member]
Restructuring Cost And Reserve [Line Items]
Liability, beginning balance		1,585	8
Net accruals		39	5,765
Payments		$ (1,624)	(3,043)
Non-cash	[1]		(1,145)
Liability, ending balance			$ 1,585

[1] Primarily represents the reclassification of current period charges for share-based compensation.