Note 13 - Earnings Per Share - Computations of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net income									$ 11,101	$ 21,436	$ 13,491
Basic (in shares)	6,400	6,439	6,551	7,121	7,116	7,186	7,431	7,425	6,627	7,288	7,990
Dilutive effect of common stock equivalents (in shares)									22	37	44
Diluted (in shares)	6,425	6,458	6,572	7,145	7,144	7,219	7,474	7,467	6,649	7,325	8,034
Basic (in dollars per share)	$ 0.11	$ 0.54	$ 0.61	$ 0.41	$ 0.45	$ 0.81	$ 0.95	$ 0.72	$ 1.68	$ 2.94	$ 1.69
Diluted (in dollars per share)	$ 0.11	$ 0.53	$ 0.61	$ 0.41	$ 0.45	$ 0.80	$ 0.94	$ 0.72	$ 1.67	$ 2.93	$ 1.68

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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