Property and Equipment, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property and equipment	$ 1,924,627	$ 1,863,624
Accumulated depreciation	(1,121,064)	(1,106,913)
Total property and equipment, net	$ 803,563	$ 756,711