Note 8 - Income Taxes (Details) - Reconciliation of Income Tax Expense - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Income Tax Expense [Abstract]
Computed at the statutory rate (35%)	$ 37,543	$ 17,601	$ 11,387
Increase (decrease) in taxes resulting from:
State income taxes, net of federal tax benefit	2,097	41	825
Tax exempt interest income	(4,708)	(3,774)	(2,739)
Tax exempt earnings on BOLI	(724)	(499)	(461)
Section 382 adjustment	(2,293)	0	0
Other differences, net	985	1,233	293
Actual tax provision	$ 32,900	$ 14,602	$ 9,305