Note 4 - Loans and Allowance for Loan Losses (Details) - Loans by Credit Risk Rating, Segregated by Class of Loans - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Consumer:
Credit risk	$ 4,919,355	$ 2,736,634
Credit risk	1,672,901	575,980
Loans acquired, covered by FDIC loss share		106,933
Risk Rate 1-4 [Member]
Consumer:
Credit risk	4,745,322	2,642,549
Credit risk	1,590,384	535,728
Loans acquired, covered by FDIC loss share		106,933
Risk Rate 5 [Member]
Consumer:
Credit risk	20,334	11,938
Credit risk	9,150	1,435
Risk Rate 6 [Member]
Consumer:
Credit risk	148,719	80,152
Credit risk	69,219	36,958
Risk Rate 7 [Member]
Consumer:
Credit risk	4,521	1,990
Credit risk	3,689	1,854
Risk Rate 8 [Member]
Consumer:
Credit risk	459	5
Credit risk	459	5
Consumer Portfolio Segment [Member]
Consumer:
Credit risk	385,668	288,782
Consumer Portfolio Segment [Member] | Risk Rate 1-4 [Member]
Consumer:
Credit risk	383,878	287,438
Consumer Portfolio Segment [Member] | Risk Rate 5 [Member]
Consumer:
Credit risk		5
Consumer Portfolio Segment [Member] | Risk Rate 6 [Member]
Consumer:
Credit risk	1,741	1,296
Consumer Portfolio Segment [Member] | Risk Rate 7 [Member]
Consumer:
Credit risk	49	43
Consumer Portfolio Segment [Member] | Credit Card Receivable [Member]
Consumer:
Credit risk	177,288	185,380
Consumer Portfolio Segment [Member] | Credit Card Receivable [Member] | Risk Rate 1-4 [Member]
Consumer:
Credit risk	176,809	184,923
Consumer Portfolio Segment [Member] | Credit Card Receivable [Member] | Risk Rate 6 [Member]
Consumer:
Credit risk	479	457
Consumer Portfolio Segment [Member] | Other Loans [Member]
Consumer:
Credit risk	208,380	103,402
Consumer Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Credit risk	207,069	102,515
Consumer Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 5 [Member]
Consumer:
Credit risk		5
Consumer Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 6 [Member]
Consumer:
Credit risk	1,262	839
Consumer Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 7 [Member]
Consumer:
Credit risk	49	43
Commercial Real Estate Portfolio Segment [Member]
Consumer:
Credit risk	2,204,992	1,352,328
Commercial Real Estate Portfolio Segment [Member] | Risk Rate 1-4 [Member]
Consumer:
Credit risk	2,128,687	1,321,194
Commercial Real Estate Portfolio Segment [Member] | Risk Rate 5 [Member]
Consumer:
Credit risk	8,424	8,934
Commercial Real Estate Portfolio Segment [Member] | Risk Rate 6 [Member]
Consumer:
Credit risk	67,104	22,118
Commercial Real Estate Portfolio Segment [Member] | Risk Rate 7 [Member]
Consumer:
Credit risk	777	82
Commercial Real Estate Portfolio Segment [Member] | Other Loans [Member]
Consumer:
Credit risk	1,229,072	714,797
Commercial Real Estate Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Credit risk	1,178,817	698,329
Commercial Real Estate Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 5 [Member]
Consumer:
Credit risk	5,404	7,074
Commercial Real Estate Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 6 [Member]
Consumer:
Credit risk	44,261	9,394
Commercial Real Estate Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 7 [Member]
Consumer:
Credit risk	590
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Consumer:
Credit risk	279,740	181,968
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Credit risk	270,386	176,825
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Risk Rate 5 [Member]
Consumer:
Credit risk	319	84
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Risk Rate 6 [Member]
Consumer:
Credit risk	9,019	5,059
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Risk Rate 7 [Member]
Consumer:
Credit risk	16
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member]
Consumer:
Credit risk	696,180	455,563
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Credit risk	679,484	446,040
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Risk Rate 5 [Member]
Consumer:
Credit risk	2,701	1,776
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Risk Rate 6 [Member]
Consumer:
Credit risk	13,824	7,665
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Risk Rate 7 [Member]
Consumer:
Credit risk	171	82
Commercial Portfolio Segment [Member]
Consumer:
Credit risk	648,679	407,478
Commercial Portfolio Segment [Member] | Risk Rate 1-4 [Member]
Consumer:
Credit risk	635,351	386,123
Commercial Portfolio Segment [Member] | Risk Rate 5 [Member]
Consumer:
Credit risk	2,760	1,564
Commercial Portfolio Segment [Member] | Risk Rate 6 [Member]
Consumer:
Credit risk	10,562	19,780
Commercial Portfolio Segment [Member] | Risk Rate 7 [Member]
Consumer:
Credit risk	6	11
Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Consumer:
Credit risk	500,116	291,820
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Credit risk	487,563	271,017
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Risk Rate 5 [Member]
Consumer:
Credit risk	2,760	1,544
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Risk Rate 6 [Member]
Consumer:
Credit risk	9,787	19,248
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Risk Rate 7 [Member]
Consumer:
Credit risk	6	11
Commercial Portfolio Segment [Member] | Agricultural Loans [Member]
Consumer:
Credit risk	148,563	115,658
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Credit risk	147,788	115,106
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Risk Rate 5 [Member]
Consumer:
Credit risk		20
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Risk Rate 6 [Member]
Consumer:
Credit risk	775	532
Unallocated Financing Receivables [Member]
Consumer:
Credit risk	7,115	5,133
Unallocated Financing Receivables [Member] | Risk Rate 1-4 [Member]
Consumer:
Credit risk	7,022	$ 5,133
Unallocated Financing Receivables [Member] | Risk Rate 6 [Member]
Consumer:
Credit risk	$ 93