Note 6 - Stockholders' Equity, Stock Plans and Stock-based Compensation Expense (Details) - Restricted Stock Units Activity (Restricted Stock Units (RSUs) [Member], USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Restricted Stock Units (RSUs) [Member]
Note 6 - Stockholders' Equity, Stock Plans and Stock-based Compensation Expense (Details) - Restricted Stock Units Activity [Line Items]
Number of shares outstanding, balance	434,321		179,465		148,709		55,253
Shares outstanding, weighted-average grant-date fair value	$ 9.31		$ 8.34		$ 6.99		$ 9.55
Shares outstanding, aggregate intrinsic value	$ 4,639	[1]	$ 1,827	[1]	$ 1,338	[1]	$ 412	[1]
Shares vested, number of shares	(81,157)	[2]	(119,505)	[2]	(41,522)	[2]
Shares vested, weighted-average grant-date fair value	$ 8.62	[2]	$ 7.68	[2]	$ 9.79	[2]
Shares vested, aggregate fair value	$ 777	[2],[3],[4]	$ 1,091	[2],[3],[5]	$ 279	[2],[3],[6]
Shares forfeited, number of shares	(24,550)		(38,417)		(13,210)
Shares forfeited, weighted-average grant-date fair value	$ 8.14		$ 8.11		$ 7.39
Number of shares granted	360,563		188,678		148,188
Shares granted, weighted-average grant-date fair value	$ 9.72		$ 8.94		$ 6.85

[1] Based on the closing stock price of the Company's stock of $10.68 on December 31, 2014, $10.18 on December 31, 2013, $9.00 on December 30, 2012 and $7.45 on December 31, 2011.

[2] The number of restricted stock units vested includes shares that the Company withheld on behalf of the employees to satisfy the statutory tax withholding requirements.

[3] Represents the value of the Company's stock on the date that the restricted stock units vest.

[4] On the grant date, the fair value for these vested awards was $699,000.

[5] On the grant date, the fair value for these vested awards was $917,000.

[6] On the grant date, the fair value for these vested awards was $407,000.