Note 5 - Loans Acquired (Details) - Summary of Acquired Loans, Excluding Loans Covered by Loss Share - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	$ 4,919,355	$ 2,736,634
Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	4,745,322	2,642,549
Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	20,334	11,938
Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	148,719	80,152
Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	4,521	1,990
Risk Rate 8 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	459	5
Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	1,672,901	575,980
Acquired Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	1,590,384	535,729
Acquired Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	9,150	1,435
Acquired Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	69,219	36,957
Acquired Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	3,689	1,854
Acquired Loans [Member] | Risk Rate 8 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	459	5
Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	385,668	288,782
Consumer Portfolio Segment [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	383,878	287,438
Consumer Portfolio Segment [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans		5
Consumer Portfolio Segment [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	1,741	1,296
Consumer Portfolio Segment [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	49	43
Consumer Portfolio Segment [Member] | Other Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	208,380	103,402
Consumer Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	207,069	102,515
Consumer Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans		5
Consumer Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	1,262	839
Consumer Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	49	43
Consumer Portfolio Segment [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	75,606	8,511
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	75,330	8,479
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	0	0
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	276	32
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	0	0
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Risk Rate 8 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	0	0
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	75,606	8,511
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	75,330	8,479
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	0	0
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	276	32
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	0	0
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Risk Rate 8 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	0	0
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	2,204,992	1,352,328
Commercial Real Estate Portfolio Segment [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	2,128,687	1,321,194
Commercial Real Estate Portfolio Segment [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	8,424	8,934
Commercial Real Estate Portfolio Segment [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	67,104	22,118
Commercial Real Estate Portfolio Segment [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	777	82
Commercial Real Estate Portfolio Segment [Member] | Other Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	1,229,072	714,797
Commercial Real Estate Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	1,178,817	698,329
Commercial Real Estate Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	5,404	7,074
Commercial Real Estate Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	44,261	9,394
Commercial Real Estate Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	590
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	279,740	181,968
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	270,386	176,825
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	319	84
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	9,019	5,059
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	16
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	696,180	455,563
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	679,484	446,040
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	2,701	1,776
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	13,824	7,665
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	171	82
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	1,432,189	516,108
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	1,360,505	480,635
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	8,818	1,366
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	60,732	32,248
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	1,675	1,854
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Risk Rate 8 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	459	5
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	854,068	334,168
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	812,537	317,965
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	7,328	605
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	33,748	15,598
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	0	0
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Other Loans [Member] | Risk Rate 8 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	455	0
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Construction Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	77,119	36,847
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Construction Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	68,775	27,430
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Construction Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	0	78
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Construction Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	8,344	9,339
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Construction Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	0	0
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Construction Loans [Member] | Risk Rate 8 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	0	0
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Single Family Residential Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	501,002	145,093
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Single Family Residential Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	479,193	135,240
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Single Family Residential Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	1,490	683
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Single Family Residential Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	18,640	7,311
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Single Family Residential Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	1,675	1,854
Commercial Real Estate Portfolio Segment [Member] | Acquired Loans [Member] | Single Family Residential Loans [Member] | Risk Rate 8 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	4	5
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	648,679	407,478
Commercial Portfolio Segment [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	635,351	386,123
Commercial Portfolio Segment [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	2,760	1,564
Commercial Portfolio Segment [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	10,562	19,780
Commercial Portfolio Segment [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	6	11
Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	500,116	291,820
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	487,563	271,017
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	2,760	1,544
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	9,787	19,248
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	6	11
Commercial Portfolio Segment [Member] | Agricultural Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	148,563	115,658
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	147,788	115,106
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans		20
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	775	532
Commercial Portfolio Segment [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	165,106	51,361
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	154,549	46,615
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	332	69
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	8,211	4,677
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	2,014	0
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Risk Rate 8 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	0	0
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	154,533	47,261
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Commercial Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	144,239	43,585
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Commercial Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	332	69
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Commercial Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	7,948	3,607
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Commercial Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	2,014	0
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Commercial Loans [Member] | Risk Rate 8 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	0	0
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Agricultural Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	10,573	4,100
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Agricultural Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	10,310	3,030
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Agricultural Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	0	0
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Agricultural Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	263	1,070
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Agricultural Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	0	0
Commercial Portfolio Segment [Member] | Acquired Loans [Member] | Agricultural Loans [Member] | Risk Rate 8 [Member]
Financing Receivable, Recorded Investment [Line Items]
Acquired loans	$ 0	$ 0