Note 3 - Earnings Per Share - Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended						9 Months Ended
		Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Net income		$ 10,724	$ 10,556	$ 7,068	$ 17,333	$ 13,923	$ 11,412	$ 28,348	$ 42,668
Divided by:
Weighted average common shares outstanding (in shares)		28,730			28,604			28,704	28,806
Weighted average common stock equivalents (in shares)		0			0			0	1
Total weighted average common shares outstanding and common stock equivalents (in shares)		28,730			28,604			28,704	28,807
Basic earnings per common share (in dollars per share)		$ 0.37			$ 0.61			$ 0.99	$ 1.48
Diluted earnings per common share (in dollars per share)	[1]	$ 0.37			$ 0.61			$ 0.99	$ 1.48
Dividend payout ratio		56.80%			32.80%			63.60%	40.50%

[1] For the three and nine months ended September 30, 2019 and 2018, there were no common stock equivalents that were anti-dilutive.