Property and Equipment, Net - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 25,700	$ 21,800	$ 50,321	$ 41,786
Accumulated amortization for capitalized leased assets	9,100		9,100		$ 8,300
Capitalized interest	2,500	1,400
Internal use software costs capitalized	$ 113	$ 410	$ 794	$ 1,100