Quarterly Financial Information - Summary of Condensed Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014
Statement Of Financial Position [Abstract]
Cash, cash equivalents and short-term investments	$ 33,200	$ 31,577	$ 26,898	$ 27,626	$ 29,723	$ 29,311	$ 29,430	$ 26,594
Accounts receivable	21,579	19,808	19,377	21,323	19,009	15,560	15,418	13,490
Total current assets	55,657	51,844	47,059	49,683	49,312	45,395	45,557	40,799
Total assets	61,008	57,355	52,680	55,389	55,258	51,593	51,813	47,161
Third-party software fees payable	14,831	11,068	8,403	12,045	11,789	10,184	12,361	10,793
Accounts payable	283	284	328	470	188	285	191	211
Accrued compensation	2,008	1,924	2,093	1,553	2,390	2,333	2,173	1,738
Other accrued expenses	714	741	1,715	1,208	1,277	1,320	1,501	1,374
Total current liabilities	20,221	15,502	13,407	16,322	17,077	15,120	17,147	14,951
Common stock	135,660	135,043	134,264	133,774	133,331	132,601	131,962	131,410
Accumulated deficit	(96,607)	(95,346)	(95,240)	(846)	(95,555)	(96,695)	(97,940)	(99,825)
Total shareholders' equity	38,112	38,790	38,166	37,873	36,907	35,077	33,189	30,662	$ 28,577
Total liabilities and shareholders' equity	$ 61,008	$ 57,355	$ 52,680	$ 55,389	$ 55,258	$ 51,593	$ 51,813	$ 47,161