Consolidated Statements of Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Revenues	$ 75,757	$ 61,860
Costs and operating expenses:
Cost of revenue (exclusive of depreciation and amortization presented separately below)	6,392	6,225
Sales and marketing (includes related party expenses of $4,056 and $3,301 for the three months ended March 31, 2017 and 2016, respectively)	42,182	32,111
Technology and development	13,629	13,140
General and administrative	13,628	15,496
Depreciation and amortization	6,084	5,904
Total costs and operating expenses	81,915	72,876
Loss from operations	(6,158)	(11,016)
Interest income	133	93
Interest expense	(649)	(608)
Loss before provision for income taxes	(6,674)	(11,531)
Provision for income taxes	121	136
Net loss	$ (6,795)	$ (11,667)
Net loss per share attributable to common stockholders:
Net loss per share, basic and diluted (in dollars per share)	$ (0.08)	$ (0.14)
Weighted average common shares outstanding, basic and diluted (in shares)	86,783	83,462
Other comprehensive loss:
Comprehensive loss	$ (6,795)	$ (11,667)