Condensed Consolidated Statements of Income (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Condensed Consolidated Statements of Income [Abstract]
Revenue	$ 37,982	$ 30,695	$ 110,827	$ 91,490
Costs and expenses:
Cost of revenue	5,426	2,503	15,164	7,490
Cost of revenue-amortization of acquired technology	1,085	798	2,965	2,373
Total cost of revenue	6,511	3,301	18,129	9,863
Gross profit	31,471	27,394	92,698	81,627
Operating expenses:
Marketing and selling	8,614	8,169	26,605	24,198
Research and development	4,617	4,116	13,549	12,176
General and administrative	4,386	4,284	14,011	12,621
Amortization of other intangible assets	1,405	1,252	4,057	3,847
Total operating expenses	19,022	17,821	58,222	52,842
Income from operations	12,449	9,573	34,476	28,785
Other (income) expense:
Interest expense	457	587	1,461	2,388
Interest income	(6)	(29)	(22)	(91)
Loss (gain) on foreign exchange	24	215	301	(266)
Loss (gain) on derivatives	65	(536)	(14)	487
Loss on extinguishment of debt		422		422
Other expense net	33	2	19	2
Total other expense	573	661	1,745	2,942
Income before provision for income taxes	11,876	8,912	32,731	25,843
Provision for income taxes	3,886	2,920	11,606	8,813
Net income	7,990	5,992	21,125	17,030
Net income available to common stockholders-basic & diluted	$ 7,857	$ 5,891	$ 20,779	$ 16,753
Net income per common share:
Basic	$ 0.22	$ 0.17	$ 0.57	$ 0.48
Diluted	$ 0.21	$ 0.16	$ 0.55	$ 0.46
Weighted average number of shares:
Basic	36,323,556	35,447,484	36,217,950	35,267,592
Diluted	37,620,269	36,829,518	37,600,448	36,703,298
Dividends declared per share	$ 0.04		$ 0.04