CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) [Abstract]
Revenues	$ 58,065	$ 58,906	$ 115,281	$ 109,179
Cost of revenues	11,390	12,355	23,256	23,589
Gross profit	46,675	46,551	92,025	85,590
Operating expenses:
Engineering and product development	814	760	1,587	1,518
Selling and marketing	30,468	31,068	59,794	56,903
General and administrative	6,268	9,243	11,927	16,362
Total operating expenses	37,550	41,071	73,308	74,783
Operating profit	9,125	5,480	18,717	10,807
Other income (loss):
Interest and other financing income (expense), net	(134)	(401)	(3)	(631)
Income before income tax expense	8,991	5,079	18,714	10,176
Income tax expense	(1,897)	(866)	(4,408)	(1,106)
Net income	7,094	4,213	14,306	9,070
Net income per share:
Basic (in dollars per share)	$ 0.34	$ 0.21	$ 0.69	$ 0.47
Diluted (in dollars per share)	$ 0.34	$ 0.20	$ 0.68	$ 0.45
Shares used in computing net income per share:
Basic (in shares)	20,573,048	20,547,244	20,624,588	19,454,775
Diluted (in shares)	21,033,349	21,034,814	21,084,889	19,942,345
Other comprehensive income (loss):
Foreign currency translation adjustments	21	(90)	(1,792)	(95)
Comprehensive income	$ 7,115	$ 4,123	$ 12,514	$ 8,975