Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidated Statements of Operations
Revenue	$ 166,761	$ 173,837	$ 159,487
Cost of revenue	90,488	99,266	101,673
Gross profit	76,273	74,571	57,814
Operating expenses:
Technology and development	21,045	20,171	16,992
Sales and marketing	48,361	48,879	42,623
General and administrative	17,010	17,279	14,712
Depreciation and amortization	9,173	8,344	6,675
Mark-to-market	1,263
Impairment charges		22,665
Total operating expenses	96,852	117,338	81,002
Loss from operations	(20,579)	(42,767)	(23,188)
Interest and other income, net:
Interest expense	(129)	(10)	(4)
Other income, net	(123)	30	46
Total interest and other income, net	(252)	20	42
Loss before provision for income taxes	(20,831)	(42,747)	(23,146)
Provision for income taxes	116	483	343
Net loss	$ (20,947)	$ (43,230)	$ (23,489)
Net loss per share attributable to common stockholders:
Basic and diluted (in dollars per share)	$ (0.40)	$ (0.84)	$ (0.46)
Weighted-average number of shares of common stock outstanding:
Basic and diluted (in shares)	52,279,738	51,684,397	50,637,541