Note 6 - Loans Acquired - Carrying Value of all Acquired Impaired Loans (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Acquired loans	[1]	$ 1,092,039	$ 1,305,683
Consumer Portfolio Segment [Member]
Acquired loans		29,662	49,677
Commercial Real Estate Portfolio Segment [Member]
Acquired loans		978,309	1,170,871
Commercial Portfolio Segment [Member]
Acquired loans		84,068	85,135
Other Loans [Member] | Consumer Portfolio Segment [Member]
Acquired loans		29,662	49,677
Other Loans [Member] | Commercial Real Estate Portfolio Segment [Member]
Acquired loans		565,993	690,108
Construction Loans [Member] | Commercial Real Estate Portfolio Segment [Member]
Acquired loans		48,520	57,587
Single Family Residential Loans [Member] | Commercial Real Estate Portfolio Segment [Member]
Acquired loans		363,796	423,176
Commercial Loans [Member] | Commercial Portfolio Segment [Member]
Acquired loans		70,620	81,837
Agricultural Loans [Member] | Commercial Portfolio Segment [Member]
Acquired loans		$ 13,448	$ 3,298

[1] Loans acquired are reported net of a $391,000 and $954,000 allowance at September 30, 2017 and December 31, 2016, respectively.