CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) [Abstract]
Revenues	$ 45,893	$ 56,681	$ 161,174	$ 165,860
Cost of revenues	9,066	11,281	32,322	34,870
Gross profit	36,827	45,400	128,852	130,990
Operating expenses:
Engineering and product development	805	628	2,392	2,146
Selling and marketing	30,973	28,285	90,767	85,188
General and administrative	5,972	6,231	17,899	22,593
Total operating expenses	37,750	35,144	111,058	109,927
Operating profit	(923)	10,256	17,794	21,063
Other income (loss):
Interest and other financing income (expense), net	473	(231)	470	(862)
Income (loss) before income tax expense	(450)	10,025	18,264	20,201
Income tax expense (benefit)	(1,336)	2,500	3,072	3,606
Net income	886	7,525	15,192	16,595
Net income per share:
Basic (in dollars per share)	$ 0.04	$ 0.35	$ 0.74	$ 0.83
Diluted (in dollars per share)	$ 0.04	$ 0.35	$ 0.72	$ 0.81
Shares used in computing net income per share:
Basic (in shares)	19,982,967	21,205,675	20,518,493	20,001,456
Diluted (in shares)	20,441,262	21,752,845	20,976,788	20,548,626
Other comprehensive income (loss):
Foreign currency translation adjustments	1,884	961	92	865
Comprehensive income	$ 2,770	$ 8,486	$ 15,284	$ 17,460