Condensed Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Revenue	$ 48,733	$ 46,405	$ 98,575	$ 92,451
Cost of revenue	7,588	7,553	15,907	14,963
Cost of revenue-amortization of acquired technology	1,131	1,134	2,262	2,267
Total cost of revenue	8,719	8,687	18,169	17,230
Gross profit	40,014	37,718	80,406	75,221
Operating expenses:
Marketing and selling	14,648	14,532	28,735	27,508
Research and development	5,991	5,290	13,327	11,089
General and administrative	8,638	7,010	17,487	13,909
Amortization of other intangible assets	742	790	1,477	1,492
Total operating expenses	30,019	27,622	61,026	53,998
Income from operations	9,995	10,096	19,380	21,223
Other (income) expense:
Interest expense	162	449	324	795
Interest income	(72)	(145)	(126)	(257)
(Gain) loss on foreign exchange	(373)	498	434	612
(Gain) loss on derivatives	(200)	208	(206)	72
Other income, net	(32)	(1)	(21)	(2)
Total other (income) expense	(515)	1,009	405	1,220
Income before provision for income taxes	10,510	9,087	18,975	20,003
Provision for income taxes	3,857	3,183	6,964	6,742
Net income	6,653	5,904	12,011	13,261
Net income available to common stockholders-basic	6,447	5,754	11,668	12,960
Net income available to common stockholders-diluted	$ 6,447	$ 5,755	$ 11,669	$ 12,962
Net income per common share:
Basic	$ 0.16	$ 0.15	$ 0.30	$ 0.33
Diluted	$ 0.16	$ 0.15	$ 0.29	$ 0.33
Weighted average number of shares outstanding:
Basic	39,377,945	38,826,185	39,250,297	38,827,668
Diluted	39,748,905	39,395,395	39,635,262	39,458,758
Dividends declared per common share	$ 0.11	$ 0.10	$ 0.22	$ 0.20