Capitalized Software (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Research and Development [Abstract]
Capitalized internal-use software development costs	$ 146,261	$ 120,268
Less: Accumulated amortization	(99,625)	(80,470)
Capitalized software, net	46,636	39,798
Finite-Lived Intangible Assets [Line Items]
Amortization computer software expense	19,159	19,029	$ 15,716
Cost of revenue
Finite-Lived Intangible Assets [Line Items]
Amortization computer software expense	18,508	17,730	14,777
Sales and marketing
Finite-Lived Intangible Assets [Line Items]
Amortization computer software expense	162	323	206
General and administrative
Finite-Lived Intangible Assets [Line Items]
Amortization computer software expense	$ 489	$ 976	$ 733