Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Revenue	$ 276,153	$ 255,821	$ 234,496
Cost of revenue	75,966	69,348	64,885
Gross profit	200,187	186,473	169,611
Operating expenses:
Sales and marketing	124,006	115,867	108,428
General and administrative	73,589	69,911	57,063
Product development	25,790	22,429	20,014
Total operating expenses	223,385	208,207	185,505
Loss from operations	(23,198)	(21,734)	(15,894)
Interest expense	4,435	4,202	4,136
Amortization of debt issuance costs	571	579	358
Other expense, net	1,335	1,746	239
Net loss before income tax	(29,539)	(28,261)	(20,627)
Income tax expense (benefit)	845	(1,765)	(5,349)
Net loss	$ (30,384)	$ (26,496)	$ (15,278)
Net loss per common share
Basic (in dollars per share)	$ (0.53)	$ (0.47)	$ (0.28)
Diluted (in dollars per share)	$ (0.53)	$ (0.47)	$ (0.28)
Weighted average number of shares
Basic (in shares)	57,172,659	55,932,641	55,135,657
Diluted (in shares)	57,172,659	55,932,641	55,135,657