Property and Equipment, net - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 135,991	$ 115,047
Less: Accumulated depreciation	(65,281)	(48,106)
Total property and equipment, net	70,710	66,941
Computer equipment, software, and internally developed software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	83,568	65,973
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	4,779	3,705
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	8,342	6,067
Capitalized facility leases
Property, Plant and Equipment [Line Items]
Property and equipment, gross	39,302	39,302
Less: Accumulated depreciation	$ (2,200)	$ (1,200)