Note 4 - Stock-based Compensation - Stock Options Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Options Outstanding, Number (in shares)	3	76	221
Options Outstanding, Weighted average exercise price (in dollars per share)	$ 12.79	$ 14.73	$ 14.98
Options Outstanding, Weighted average remaining contractual term (Year)		146 days	182 days	1 year
Options Exercised, Number (in shares)	(3)	(73)	(45)
Options Exercised, Weighted average exercise price (in dollars per share)	$ 12.79	$ 14.79	$ 13.64
Options Forfeited, Number (in shares)			(100)
Options forfeited, Weighted average exercise price (in dollars per share)			$ 21.71
Options Outstanding, Number (in shares)		3	76	221
Options Outstanding, Weighted average exercise price (in dollars per share)		$ 12.79	$ 14.73	$ 14.98
Options Outstanding, Aggregate Intrinsic Value		$ 15	$ 945
Options Exercisable, Number (in shares)
Options Exercisable, Weighted average exercise price (in dollars per share)
Options Exercisable, Weighted average remaining contractual term (Year)
Options Exercisable, Aggregate Intrinsic Value