Note 1 - Calculation of Earnings Per Share (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Numerator:
Net income	$ 42,085	$ 17,808	$ 5,244
Denominator:
Denominator for basic income per share – weighted-average shares (in shares)	18,145,000	15,250,000	14,837,000
Effect of dilutive securities:
Equivalent shares issuable upon conversion of unvested restricted shares (in shares)	161,000	266,000	202,000
Equivalent shares issuable upon conversion of unvested employee stock options (in shares)	5,000	1,000	0
Denominator for diluted income per share adjusted weighted-average shares and assumed conversions (in shares)	18,311,000	15,517,000	15,039,000
Income per share:
Basic income per share (in dollars per share)	$ 2.32	$ 1.17	$ 0.35
Diluted income per share (in dollars per share)	$ 2.30	$ 1.15	$ 0.35