Note 2 - Earnings Per Share - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Net income available to common stockholders	$ 988	$ 14,673	$ 134	$ 10,798	$ 15,661	$ 10,932
Weighted average shares outstanding
Total weighted average shares outstanding, basic (in shares)	46,155,981		45,894,155		45,607,307	45,322,541
Dilutive potential common shares (in shares)	3,329,023		548,456		2,673,695	272,439
Total weighted average shares outstanding, diluted (in shares)	49,485,004		46,442,611		48,281,002	45,594,980
Net income per share available to common stockholders
Basic (in dollars per share)	$ 0.02				$ 0.34	$ 0.24
Diluted (in dollars per share)	$ 0.02				$ 0.32	$ 0.24