Note 6 - Stockholders' Equity, Stock Plans and Stock-based Compensation Expense (Tables)

12 Months Ended

Dec. 31, 2014

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

				Options Outstanding
	Shares Available For Grant			Number of Shares			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value (in $ millions)(1)
Balances as of December 31, 2011		474,537			3,549,022		$	9.92		4.6		0.4
Additional shares reserved(2)		1,910,000			—			—
Options granted		(921,500	)		921,500		$	7.04
Options exercised		—			(211,551	)	$	7.00
Options cancelled (expired or forfeited)		470,732			(470,732	)	$	9.45
Stock awards granted		(314,159	)		—			—
Stock awards cancelled (expired or forfeited)		24,746			—			—
Balances as of December 31, 2012		1,644,356			3,788,239		$	9.44		4.3	$	2.6
Options granted		(1,007,166	)		1,007,166		$	8.97
Options exercised		—			(612,210	)	$	8.16
Options cancelled (expired or forfeited)		391,033			(391,033	)	$	10.37
Stock awards granted		(399,997	)		—			—
Stock awards cancelled (expired or forfeited)		81,257			—			—
Balances as of December 31, 2013		709,483			3,792,162		$	9.42		4.2	$	5.1
Additional shares reserved(3)		200,000			—			—
Options granted		(486,300	)		486,300		$	9.78
Options exercised		—			(396,970	)	$	8.33
Options cancelled (expired or forfeited)		418,925			(418,925	)	$	11.15
Stock awards granted		(764,394	)		—			—
Stock awards cancelled (expired or forfeited)		52,046			—			—
Balances as of December 31, 2014		129,760			3,462,567		$	9.39		3.4	$	5.7
Exercisable as of December 31, 2014					2,330,762		$	9.62		2.7	$	3.7
Expected to vest, net of estimated forfeitures, as of December 31, 2014					909,562		$	8.86		4.96	$	1.7

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]

		Options Outstanding			Options Exercisable
Range of Exercise Price		Number Outstanding	Weighted-Average Remaining Contractual Life (in years)		Number Outstanding		Weighted-Average Exercise Price
$	6.54	17,125		1.30		17,125	$	6.54
$	6.88	460,530		4.37		278,266		6.88
$	7.11–$ 8.66	442,525		1.63		428.942		8.53
$	8.72	473,989		3.21		431,615		8.72
$	8.80	553,795		5.08		196,926		8.80
$	8.81–$9.65	432,778		5.47		114,960		9.15
$	9.74–$10.03	183,000		4.66		28,000		9.74
$	10.24	441,325		2.21		441,325		10.24
$	10.32–$14.78	354,500		1.36		290,603		11.14
$	16.25–$25.73	103,000		0.81		103,000		20.93
$	6.54–$25.73	3,462,567		3.42		2,330,762	$	9.62

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

	Number of Shares			Weighted-Average Grant- Date Fair Value		Aggregate Fair Value(1) (in thousands)			Aggregate Intrinsic Value(2) (in thousands)
Outstanding at December 31, 2011		55,253		$	9.55				$	412
Granted		148,188		$	6.85
Vested (3)		(41,522	)	$	9.79	$	279	(4)
Forfeited		(13,210	)	$	7.39
Outstanding at December 31, 2012		148,709		$	6.99				$	1,338
Granted		188,678		$	8.94
Vested (3)		(119,505	)	$	7.68	$	1,091	(5)
Forfeited		(38,417	)	$	8.11
Outstanding at December 31, 2013		179,465		$	8.34				$	1,827
Granted		360,563		$	9.72
Vested (3)		(81,157	)	$	8.62	$	777	(6)
Forfeited		(24,550	)	$	8.14
Outstanding at December 31, 2014		434,321		$	9.31				$	4,639

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]

	Year Ended December 31,
	2014		2013		2012
Stock options	$	1,811	$	2,201	$	2,421
RSUs		875		631		501
PSUs		455		162		138
ESPP		158		116		100
Total stock-based compensation expense	$	3,299	$	3,110	$	3,160

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

	Year Ended December 31,
	2014		2013		2012
Cost of revenue	$	560	$	638	$	658
Sales and marketing		641		744		657
Research and development		581		397		514
General and administrative		1,517		1,331		1,331
Total stock-based compensation expense	$	3,299	$	3,110	$	3,160

Valuation Assumptions and Fair Value of Stock Options and ESPP Grants [Table Text Block]

	Stock Options									Stock Purchase Plan
	2014			2013			2012			2014			2013			2012
Expected term (in years)(1)		4.18			4.30			4.17			0.50			0.50			0.50
Risk-free interest rate(2)		1.31	%		1.13	%		0.45	%		0.06	%		0.08	%		0.15	%
Volatility(3)		41	%		43	%		44	%		37	%		44	%		43	%
Dividend yield(4)		—	%		—	%		—	%		—	%		—	%		—	%
Weighted average estimated fair value at grant date	$	3.36		$	3.22		$	2.47		$	2.65		$	2.84		$	2.16