Note 4 - Loans and Allowance for Loan Losses (Details) - Loans by Credit Risk Rating, Segregated by Class of Loans (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Consumer:
Financing receivables	$ 2,736,634	$ 2,404,935
Loans acquired, not covered by FDIC loss share	575,980	515,644
Loans acquired, covered by FDIC loss share	106,933	146,653
Credit Cards [Member] | Consumer Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Financing receivables	184,923	184,415
Credit Cards [Member] | Consumer Loans [Member] | Risk Rate 6 [Member]
Consumer:
Financing receivables	457	520
Credit Cards [Member] | Consumer Loans [Member]
Consumer:
Financing receivables	185,380	184,935
Other Consumer [Member] | Consumer Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Financing receivables	102,515	97,655
Other Consumer [Member] | Consumer Loans [Member] | Risk Rate 5 [Member]
Consumer:
Financing receivables	5	2
Other Consumer [Member] | Consumer Loans [Member] | Risk Rate 6 [Member]
Consumer:
Financing receivables	839	1,121
Other Consumer [Member] | Consumer Loans [Member] | Risk Rate 7 [Member]
Consumer:
Financing receivables	43	56
Other Consumer [Member] | Consumer Loans [Member] | Risk Rate 8 [Member]
Consumer:
Financing receivables		17
Other Consumer [Member] | Consumer Loans [Member]
Consumer:
Financing receivables	103,402	98,851
Consumer Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Financing receivables	287,438
Consumer Loans [Member] | Risk Rate 5 [Member]
Consumer:
Financing receivables	5
Consumer Loans [Member] | Risk Rate 6 [Member]
Consumer:
Financing receivables	1,296
Consumer Loans [Member] | Risk Rate 7 [Member]
Consumer:
Financing receivables	43
Consumer Loans [Member]
Consumer:
Financing receivables	288,782
Construction Loans [Member] | Real Estate Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Financing receivables	176,825	142,213
Construction Loans [Member] | Real Estate Loans [Member] | Risk Rate 5 [Member]
Consumer:
Financing receivables	84	71
Construction Loans [Member] | Real Estate Loans [Member] | Risk Rate 6 [Member]
Consumer:
Financing receivables	5,059	4,174
Construction Loans [Member] | Real Estate Loans [Member]
Consumer:
Financing receivables	181,968	146,458
Single Family Residential Loans [Member] | Real Estate Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Financing receivables	446,040	383,934
Single Family Residential Loans [Member] | Real Estate Loans [Member] | Risk Rate 5 [Member]
Consumer:
Financing receivables	1,776	1,412
Single Family Residential Loans [Member] | Real Estate Loans [Member] | Risk Rate 6 [Member]
Consumer:
Financing receivables	7,665	6,939
Single Family Residential Loans [Member] | Real Estate Loans [Member] | Risk Rate 7 [Member]
Consumer:
Financing receivables	82
Single Family Residential Loans [Member] | Real Estate Loans [Member]
Consumer:
Financing receivables	455,563	392,285
Other Commercial Real Estate Loans [Member] | Real Estate Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Financing receivables	698,329	600,045
Other Commercial Real Estate Loans [Member] | Real Estate Loans [Member] | Risk Rate 5 [Member]
Consumer:
Financing receivables	7,074	7,597
Other Commercial Real Estate Loans [Member] | Real Estate Loans [Member] | Risk Rate 6 [Member]
Consumer:
Financing receivables	9,394	18,691
Other Commercial Real Estate Loans [Member] | Real Estate Loans [Member]
Consumer:
Financing receivables	714,797	626,333
Real Estate Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Financing receivables	1,321,194
Real Estate Loans [Member] | Risk Rate 5 [Member]
Consumer:
Financing receivables	8,934
Real Estate Loans [Member] | Risk Rate 6 [Member]
Consumer:
Financing receivables	22,118
Real Estate Loans [Member] | Risk Rate 7 [Member]
Consumer:
Financing receivables	82
Real Estate Loans [Member]
Consumer:
Financing receivables	1,352,328
Commercial [Member] | Commercial Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Financing receivables	271,017	162,118
Commercial [Member] | Commercial Loans [Member] | Risk Rate 5 [Member]
Consumer:
Financing receivables	1,544	200
Commercial [Member] | Commercial Loans [Member] | Risk Rate 6 [Member]
Consumer:
Financing receivables	19,248	2,001
Commercial [Member] | Commercial Loans [Member] | Risk Rate 7 [Member]
Consumer:
Financing receivables	11	10
Commercial [Member] | Commercial Loans [Member]
Consumer:
Financing receivables	291,820	164,329
Agricultural Loans [Member] | Commercial Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Financing receivables	115,106	98,761
Agricultural Loans [Member] | Commercial Loans [Member] | Risk Rate 5 [Member]
Consumer:
Financing receivables	20
Agricultural Loans [Member] | Commercial Loans [Member] | Risk Rate 6 [Member]
Consumer:
Financing receivables	532	125
Agricultural Loans [Member] | Commercial Loans [Member]
Consumer:
Financing receivables	115,658	98,886
Other Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Financing receivables	5,133	4,655
Other Loans [Member]
Consumer:
Financing receivables	5,133	4,655
Student Loans [Member] | Consumer Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Financing receivables		23,642
Student Loans [Member] | Consumer Loans [Member] | Risk Rate 6 [Member]
Consumer:
Financing receivables		2,264
Student Loans [Member] | Consumer Loans [Member]
Consumer:
Financing receivables		25,906
Consumer Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Financing receivables		305,712
Consumer Loans [Member] | Risk Rate 5 [Member]
Consumer:
Financing receivables		2
Consumer Loans [Member] | Risk Rate 6 [Member]
Consumer:
Financing receivables		3,905
Consumer Loans [Member] | Risk Rate 7 [Member]
Consumer:
Financing receivables		56
Consumer Loans [Member] | Risk Rate 8 [Member]
Consumer:
Financing receivables		17
Consumer Loans [Member]
Consumer:
Financing receivables		309,692
Real Estate Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Financing receivables		1,126,192
Real Estate Loans [Member] | Risk Rate 5 [Member]
Consumer:
Financing receivables		9,080
Real Estate Loans [Member] | Risk Rate 6 [Member]
Consumer:
Financing receivables		29,804
Real Estate Loans [Member]
Consumer:
Financing receivables		1,165,076
Commercial Loans [Member] | Risk Rate 1-4 [Member]
Consumer:
Financing receivables	386,123	260,879
Commercial Loans [Member] | Risk Rate 5 [Member]
Consumer:
Financing receivables	1,564	200
Commercial Loans [Member] | Risk Rate 6 [Member]
Consumer:
Financing receivables	19,780	2,126
Commercial Loans [Member] | Risk Rate 7 [Member]
Consumer:
Financing receivables	11	10
Commercial Loans [Member]
Consumer:
Financing receivables	407,478	263,215
Risk Rate 1-4 [Member]
Consumer:
Financing receivables	2,642,549	2,301,188
Loans acquired, not covered by FDIC loss share	535,728	457,097
Loans acquired, covered by FDIC loss share	106,933	146,653
Risk Rate 5 [Member]
Consumer:
Financing receivables	11,938	9,282
Loans acquired, not covered by FDIC loss share	1,435
Risk Rate 6 [Member]
Consumer:
Financing receivables	80,152	94,382
Loans acquired, not covered by FDIC loss share	36,958	58,547
Risk Rate 7 [Member]
Consumer:
Financing receivables	1,990	66
Loans acquired, not covered by FDIC loss share	1,854
Risk Rate 8 [Member]
Consumer:
Financing receivables	5	17
Loans acquired, not covered by FDIC loss share	$ 5