Property, Equipment and Software, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property, equipment and software, at cost	$ 55,485	$ 42,957
Less accumulated depreciation and amortization	(26,080)	(16,770)
Property, equipment and software, net	29,405	26,187
Computer/office equipment
Property, Plant and Equipment [Line Items]
Property, equipment and software, at cost	$ 15,671	11,866
Computer/office equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	12 months
Computer/office equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	36 months
Capitalized internal-use software
Property, Plant and Equipment [Line Items]
Estimated Useful Life	36 months
Property, equipment and software, at cost	$ 21,789	15,674
Amortization expense	4,200	2,800	$ 1,800
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, equipment and software, at cost	$ 18,025	$ 15,417