Note 6 - Loans Acquired - Summary of Acquired Loans, Excluding Loans Covered by Loss Share (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Acquired loans	$ 6,303,351	$ 5,632,890
Pass [Member]
Acquired loans	6,140,412	5,433,036
Special Mention [Member]
Acquired loans	32,333	33,865
Substandard [Member]
Acquired loans	129,662	164,251
Doubtful [Member]
Acquired loans	944	1,715
Unlikely to be Collected Financing Receivable [Member]
Acquired loans		23
Acquired Loans [Member]
Acquired loans	1,092,039	1,305,683
Acquired Loans [Member] | Pass [Member]
Acquired loans	1,051,889	1,217,886
Acquired Loans [Member] | Special Mention [Member]
Acquired loans	9,673	22,181
Acquired Loans [Member] | Substandard [Member]
Acquired loans	29,862	64,075
Acquired Loans [Member] | Doubtful [Member]
Acquired loans	615	1,541
Acquired Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans
Consumer Portfolio Segment [Member]
Acquired loans	494,262	488,563
Consumer Portfolio Segment [Member] | Pass [Member]
Acquired loans	490,041	485,575
Consumer Portfolio Segment [Member] | Special Mention [Member]
Acquired loans		26
Consumer Portfolio Segment [Member] | Substandard [Member]
Acquired loans	4,221	2,962
Consumer Portfolio Segment [Member] | Doubtful [Member]
Acquired loans
Consumer Portfolio Segment [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans
Consumer Portfolio Segment [Member] | Other Loans [Member]
Acquired loans	317,946	303,972
Consumer Portfolio Segment [Member] | Other Loans [Member] | Pass [Member]
Acquired loans	313,725	301,632
Consumer Portfolio Segment [Member] | Other Loans [Member] | Special Mention [Member]
Acquired loans		26
Consumer Portfolio Segment [Member] | Other Loans [Member] | Substandard [Member]
Acquired loans	4,221	2,314
Consumer Portfolio Segment [Member] | Other Loans [Member] | Doubtful [Member]
Acquired loans
Consumer Portfolio Segment [Member] | Other Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans
Consumer Portfolio Segment [Member] | Acquired Loans [Member]
Acquired loans	29,662	49,677
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Pass [Member]
Acquired loans	28,982	48,992
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Special Mention [Member]
Acquired loans		14
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Substandard [Member]
Acquired loans	680	671
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Doubtful [Member]
Acquired loans
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member]
Acquired loans	29,662	49,677
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Pass [Member]
Acquired loans	28,982	48,992
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Special Mention [Member]
Acquired loans		14
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Substandard [Member]
Acquired loans	680	671
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Doubtful [Member]
Acquired loans
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans
Commercial Real Estate Portfolio Segment [Member]
Acquired loans	3,794,900	3,028,079
Commercial Real Estate Portfolio Segment [Member] | Pass [Member]
Acquired loans	3,705,982	2,943,890
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member]
Acquired loans	16,367	10,996
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member]
Acquired loans	72,246	73,019
Commercial Real Estate Portfolio Segment [Member] | Doubtful [Member]
Acquired loans	305	174
Commercial Real Estate Portfolio Segment [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Acquired loans	515,274	336,759
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Pass [Member]
Acquired loans	507,128	330,080
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Special Mention [Member]
Acquired loans	2,085	98
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Substandard [Member]
Acquired loans	6,045	6,565
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Doubtful [Member]
Acquired loans	16	16
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member]
Acquired loans	1,048,403	904,245
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Pass [Member]
Acquired loans	1,022,886	875,603
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Special Mention [Member]
Acquired loans	2,553	4,024
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Substandard [Member]
Acquired loans	22,675	24,460
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Doubtful [Member]
Acquired loans	289	158
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member]
Acquired loans	978,309	1,170,871
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Pass [Member]
Acquired loans	943,392	1,092,275
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Special Mention [Member]
Acquired loans	9,048	20,168
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Substandard [Member]
Acquired loans	25,254	56,893
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Doubtful [Member]
Acquired loans	615	1,535
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member]
Acquired loans	565,994	690,108
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Pass [Member]
Acquired loans	549,853	641,018
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Special Mention [Member]
Acquired loans	6,200	17,384
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Substandard [Member]
Acquired loans	9,941	31,706
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Doubtful [Member]
Acquired loans
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Construction Loans [Member]
Acquired loans	48,520	57,587
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Construction Loans [Member] | Pass [Member]
Acquired loans	45,718	50,704
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Construction Loans [Member] | Special Mention [Member]
Acquired loans	1,314	88
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Construction Loans [Member] | Substandard [Member]
Acquired loans	1,488	6,795
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Construction Loans [Member] | Doubtful [Member]
Acquired loans
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Construction Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Single Family Residential Loans [Member]
Acquired loans	363,795	423,176
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Single Family Residential Loans [Member] | Pass [Member]
Acquired loans	347,821	400,553
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Single Family Residential Loans [Member] | Special Mention [Member]
Acquired loans	1,534	2,696
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Single Family Residential Loans [Member] | Substandard [Member]
Acquired loans	13,825	18,392
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Single Family Residential Loans [Member] | Doubtful [Member]
Acquired loans	615	1,535
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Single Family Residential Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans
Commercial Portfolio Segment [Member]
Acquired loans	896,809	789,903
Commercial Portfolio Segment [Member] | Pass [Member]
Acquired loans	867,159	765,023
Commercial Portfolio Segment [Member] | Special Mention [Member]
Acquired loans	6,293	662
Commercial Portfolio Segment [Member] | Substandard [Member]
Acquired loans	23,333	24,195
Commercial Portfolio Segment [Member] | Doubtful [Member]
Acquired loans	24
Commercial Portfolio Segment [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans		23
Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Acquired loans	688,960	639,525
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Pass [Member]
Acquired loans	661,635	616,805
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Special Mention [Member]
Acquired loans	6,267	558
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Substandard [Member]
Acquired loans	21,057	22,162
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Doubtful [Member]
Acquired loans	1
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans
Commercial Portfolio Segment [Member] | Agricultural Loans [Member]
Acquired loans	207,849	150,378
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Pass [Member]
Acquired loans	205,524	148,218
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Special Mention [Member]
Acquired loans	26	104
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Substandard [Member]
Acquired loans	2,276	2,033
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Doubtful [Member]
Acquired loans	23
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans		23
Commercial Portfolio Segment [Member] | Acquired Loans [Member]
Acquired loans	84,068	85,135
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Pass [Member]
Acquired loans	79,515	76,619
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Special Mention [Member]
Acquired loans	625	1,999
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Substandard [Member]
Acquired loans	3,928	6,511
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Doubtful [Member]
Acquired loans		6
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Commercial Loans [Member]
Acquired loans	70,620	81,837
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Commercial Loans [Member] | Pass [Member]
Acquired loans	66,367	73,609
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Commercial Loans [Member] | Special Mention [Member]
Acquired loans	325	1,965
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Commercial Loans [Member] | Substandard [Member]
Acquired loans	3,928	6,257
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Commercial Loans [Member] | Doubtful [Member]
Acquired loans		6
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Commercial Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Agricultural Loans [Member]
Acquired loans	13,448	3,298
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Agricultural Loans [Member] | Pass [Member]
Acquired loans	13,148	3,010
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Agricultural Loans [Member] | Special Mention [Member]
Acquired loans	300	34
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Agricultural Loans [Member] | Substandard [Member]
Acquired loans		254
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Agricultural Loans [Member] | Doubtful [Member]
Acquired loans
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Agricultural Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Acquired loans