Property, Equipment and Software, Net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 46,208	$ 29,882	$ 21,578
General and Administrative Expense
Property, Plant and Equipment [Line Items]
Impairment	2,400	1,100	600
Property, Equipment and Software
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 40,300	$ 25,100	$ 16,200