Note 7 - Stock-Based Compensation - Stock Options (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
Outstanding, shares (in shares)	90	590	1,356
Outstanding, Weighted average exercise price (in dollars per share)	$ 17.50	$ 15.80	$ 15.86
Outstanding, Weighted average remaining contractual term (Year)	1 year	1 year 109 days	1 year 73 days	1 year 328 days
Outstanding, Aggregate intrinsic value	$ 921	$ 4,134	$ 20,039	$ 25,506
Exercised, shares (in shares)	(76)	(498)	(742)
Exercised, Weighted average exercise price (in dollars per share)	$ 17.80	$ 15.55	$ 16.09
Forfeited and expired, shares (in shares)		(2)	(24)
Forfeited and expired, Weighted average exercise price (in dollars per share)		$ 6.10	$ 10.07
Outstanding, shares (in shares)	14	90	590	1,356
Outstanding, Weighted average exercise price (in dollars per share)	$ 15.88	$ 17.50	$ 15.80	$ 15.86
Options exercisable at December 31, 2016 and expected to vest, shares (in shares)	14
Options exercisable at December 31, 2016 and expected to vest, Weighted average exercise price (in dollars per share)	$ 15.88
Options exercisable at December 31, 2016 and expected to vest, Weighted average remaining contractual term (Year)	1 year
Options exercisable at December 31, 2016 and expected to vest, Aggregate intrinsic value	$ 921
Options exercisable, shares (in shares)	14
Options exercisable, Weighted average exercise price (in dollars per share)	$ 15.88
Options exercisable, Weighted average remaining contractual term (Year)	1 year
Options exercisable, Aggregate intrinsic value	$ 921