CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) [Abstract]
Revenues	$ 57,216	$ 50,273
Cost of revenues	11,866	11,234
Gross profit	45,350	39,039
Operating expenses:
Engineering and product development	773	758
Selling and marketing	29,326	25,835
General and administrative	5,659	7,119
Total operating expenses	35,758	33,712
Operating profit	9,592	5,327
Other income (loss):
Interest and other financing income (expense), net	131	(230)
Income before income tax expense	9,723	5,097
Income tax expense	(2,511)	(240)
Net income	7,212	4,857
Net income per share:
Basic (in dollars per share)	$ 0.35	$ 0.26
Diluted (in dollars per share)	$ 0.34	$ 0.26
Shares used in computing net income per share:
Basic (in shares)	20,678,023	18,339,977
Diluted (in shares)	21,147,583	18,876,163
Other comprehensive loss:
Foreign currency translation adjustments	(1,813)	(5)
Comprehensive income	$ 5,399	$ 4,852