Note 3 - Summary of Significant Accounting Policies - Basic and Diluted Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Net income	$ 8,112	$ 7,361
Weighted average shares outstanding used in calculating basic earnings per share (in shares)	13,001	14,681
Dilutive common share equivalents (in shares)	87	87
Weighted average common and common share equivalents used in calculating diluted earnings per share (in shares)	13,088	14,768
Income per common share:
Basic (in dollars per share)	$ 0.62	$ 0.50
Diluted (in dollars per share)	$ 0.62	$ 0.50
Options and restricted share units outstanding which are not included in the calculation of diluted earnings per share because their impact is anti-dilutive (in shares)	42	157