Condensed Consolidated Statements Of Income (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Condensed Consolidated Statements Of Income [Abstract]
Revenue	$ 34,349	$ 29,729
Cost of revenue	3,658	2,026
Cost of revenue-amortization of acquired technology	795	777
Total cost of revenue	4,453	2,803
Gross profit	29,896	26,926
Operating expenses:
Marketing and selling	9,271	7,798
Research and development	4,344	4,127
General and administrative	4,927	4,193
Amortization of other intangible assets	1,221	1,291
Total operating expenses	19,763	17,409
Income from operations	10,133	9,517
Other (income) expense:
Interest expense	451	916
Interest income	(7)	(37)
Loss (gain) on foreign exchange	267	(396)
Loss on derivatives	126	672
Other	(11)
Total other expense	826	1,155
Income before provision for income taxes	9,307	8,362
Provision for income taxes	3,587	2,922
Net income	5,720	5,440
Net income available to common stockholders-basic	5,633	5,359
Net income available to common stockholders-diluted	$ 5,636	$ 5,362
Net income per common share:
Basic	$ 0.16	$ 0.15
Diluted	$ 0.15	$ 0.15
Weighted average number of shares:
Basic	36,282,428	35,041,895
Diluted	37,607,047	36,402,836