Summarized Unaudited Quarterly Results (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Unaudited Quarterly Results
Revenue	$ 50,027	$ 47,620	$ 46,407	$ 44,860	$ 43,970	$ 40,138	$ 36,257	$ 34,147	$ 188,914	$ 154,512	$ 104,941
Cost of revenue	21,980	21,346	20,836	20,816	19,959	18,284	16,586	15,774	84,978	70,603	49,979
Gross profit	28,047	26,274	25,571	24,044	24,011	21,854	19,671	18,373	103,936	83,909	54,962
Total operating expenses	26,040	24,950	24,725	23,108	21,663	20,918	19,129	17,809
Income from operations	2,007	1,324	846	936	2,348	936	542	564	5,113	4,390	2,577
Other (expense) income, net	68	253	119	420	(249)	(234)	(171)	(218)
Income before income taxes	2,075	1,577	965	1,356	2,099	702	371	346	5,973	3,518	(2,421)
Income tax provision	343	22	415	231	172	121	33	154	1,011	480	534
Net (loss) income	$ 1,732	$ 1,555	$ 550	$ 1,125	$ 1,927	$ 581	$ 338	$ 192	$ 4,962	$ 3,038	$ (2,955)
Income per common share
Basic (in dollars per share)	$ 0.05	$ 0.04	$ 0.01	$ 0.03	$ 0.05	$ 0.02	$ 0.01	$ 0.01	$ 0.13	$ 0.08	$ (0.31)
Diluted (in dollars per share)	$ 0.04	$ 0.04	$ 0.01	$ 0.03	$ 0.05	$ 0.01	$ 0.01	$ 0.00	$ 0.12	$ 0.08	$ (0.31)