Property and Equipment, net - Components of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 29,465	$ 23,976
Accumulated depreciation	(9,285)	(8,530)
Property and equipment, net	20,180	15,446
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	3,090	2,257
Computer software and equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	9,988	8,297
Internal-use software
Property, Plant and Equipment [Line Items]
Total property and equipment	1,514	975
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	1,009	8,662
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	13,466	3,387
Land
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 398	$ 398