Note 4 - Loans by Credit Risk Rating, Segregated by Class of Loans (Details) - USD ($) $ in Thousands		Mar. 31, 2016	Dec. 31, 2015
Risk Rate 1-4 [Member] | Consumer Portfolio Segment [Member] | Credit Card Receivable [Member]
Balance, end of period		$ 167,447	$ 176,809
Risk Rate 1-4 [Member] | Consumer Portfolio Segment [Member] | Other Loans [Member]
Balance, end of period		226,038	207,069
Risk Rate 1-4 [Member] | Consumer Portfolio Segment [Member]
Balance, end of period		393,485	383,878
Risk Rate 1-4 [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Balance, end of period		290,646	270,386
Risk Rate 1-4 [Member] | Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member]
Balance, end of period		722,949	679,484
Risk Rate 1-4 [Member] | Commercial Real Estate Portfolio Segment [Member] | Other Commercial Loans [Member]
Balance, end of period		1,274,015	1,178,817
Risk Rate 1-4 [Member] | Commercial Real Estate Portfolio Segment [Member]
Balance, end of period		2,287,610	2,128,687
Risk Rate 1-4 [Member] | Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Balance, end of period		534,083	487,563
Risk Rate 1-4 [Member] | Commercial Portfolio Segment [Member] | Agricultural Loans [Member]
Balance, end of period		141,186	147,788
Risk Rate 1-4 [Member] | Commercial Portfolio Segment [Member]
Balance, end of period		675,269	635,351
Risk Rate 1-4 [Member] | Unallocated Financing Receivables [Member]
Balance, end of period		8,512	7,022
Risk Rate 1-4 [Member]
Balance, end of period		4,733,970	4,745,322
Loans acquired		$ 1,369,094	$ 1,590,384
Risk Rate 5 [Member] | Consumer Portfolio Segment [Member] | Credit Card Receivable [Member]
Balance, end of period
Risk Rate 5 [Member] | Consumer Portfolio Segment [Member] | Other Loans [Member]
Balance, end of period
Risk Rate 5 [Member] | Consumer Portfolio Segment [Member]
Balance, end of period
Risk Rate 5 [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Balance, end of period		$ 135	$ 319
Risk Rate 5 [Member] | Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member]
Balance, end of period		4,165	2,701
Risk Rate 5 [Member] | Commercial Real Estate Portfolio Segment [Member] | Other Commercial Loans [Member]
Balance, end of period		5,190	5,404
Risk Rate 5 [Member] | Commercial Real Estate Portfolio Segment [Member]
Balance, end of period		9,490	8,424
Risk Rate 5 [Member] | Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Balance, end of period		2,669	$ 2,760
Risk Rate 5 [Member] | Commercial Portfolio Segment [Member] | Agricultural Loans [Member]
Balance, end of period		414
Risk Rate 5 [Member] | Commercial Portfolio Segment [Member]
Balance, end of period		$ 3,083	$ 2,760
Risk Rate 5 [Member] | Unallocated Financing Receivables [Member]
Balance, end of period
Risk Rate 5 [Member]
Balance, end of period		$ 31,602	$ 20,334
Loans acquired		19,029	9,150
Risk Rate 6 [Member] | Consumer Portfolio Segment [Member] | Credit Card Receivable [Member]
Balance, end of period		356	479
Risk Rate 6 [Member] | Consumer Portfolio Segment [Member] | Other Loans [Member]
Balance, end of period		1,418	1,262
Risk Rate 6 [Member] | Consumer Portfolio Segment [Member]
Balance, end of period		1,774	1,741
Risk Rate 6 [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Balance, end of period		9,245	9,019
Risk Rate 6 [Member] | Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member]
Balance, end of period		19,473	13,824
Risk Rate 6 [Member] | Commercial Real Estate Portfolio Segment [Member] | Other Commercial Loans [Member]
Balance, end of period		47,575	44,261
Risk Rate 6 [Member] | Commercial Real Estate Portfolio Segment [Member]
Balance, end of period		76,293	67,104
Risk Rate 6 [Member] | Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Balance, end of period		14,933	9,787
Risk Rate 6 [Member] | Commercial Portfolio Segment [Member] | Agricultural Loans [Member]
Balance, end of period		1,433	775
Risk Rate 6 [Member] | Commercial Portfolio Segment [Member]
Balance, end of period		$ 16,366	10,562
Risk Rate 6 [Member] | Unallocated Financing Receivables [Member]
Balance, end of period			93
Risk Rate 6 [Member]
Balance, end of period		$ 159,465	148,719
Loans acquired		$ 65,032	$ 69,219
Risk Rate 7 [Member] | Consumer Portfolio Segment [Member] | Credit Card Receivable [Member]
Balance, end of period
Risk Rate 7 [Member] | Consumer Portfolio Segment [Member] | Other Loans [Member]
Balance, end of period		$ 24	$ 49
Risk Rate 7 [Member] | Consumer Portfolio Segment [Member]
Balance, end of period		24	49
Risk Rate 7 [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Balance, end of period		16	16
Risk Rate 7 [Member] | Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member]
Balance, end of period		167	171
Risk Rate 7 [Member] | Commercial Real Estate Portfolio Segment [Member] | Other Commercial Loans [Member]
Balance, end of period		592	590
Risk Rate 7 [Member] | Commercial Real Estate Portfolio Segment [Member]
Balance, end of period		775	777
Risk Rate 7 [Member] | Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Balance, end of period		$ 10	$ 6
Risk Rate 7 [Member] | Commercial Portfolio Segment [Member] | Agricultural Loans [Member]
Balance, end of period
Risk Rate 7 [Member] | Commercial Portfolio Segment [Member]
Balance, end of period		$ 10	$ 6
Risk Rate 7 [Member] | Unallocated Financing Receivables [Member]
Balance, end of period
Risk Rate 7 [Member]
Balance, end of period		$ 4,565	$ 4,521
Loans acquired		$ 3,756	$ 3,689
Risk Rate 8 [Member] | Consumer Portfolio Segment [Member] | Credit Card Receivable [Member]
Balance, end of period
Risk Rate 8 [Member] | Consumer Portfolio Segment [Member] | Other Loans [Member]
Balance, end of period
Risk Rate 8 [Member] | Consumer Portfolio Segment [Member]
Balance, end of period
Risk Rate 8 [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Balance, end of period
Risk Rate 8 [Member] | Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member]
Balance, end of period
Risk Rate 8 [Member] | Commercial Real Estate Portfolio Segment [Member] | Other Commercial Loans [Member]
Balance, end of period
Risk Rate 8 [Member] | Commercial Real Estate Portfolio Segment [Member]
Balance, end of period
Risk Rate 8 [Member] | Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Balance, end of period
Risk Rate 8 [Member] | Commercial Portfolio Segment [Member] | Agricultural Loans [Member]
Balance, end of period
Risk Rate 8 [Member] | Commercial Portfolio Segment [Member]
Balance, end of period
Risk Rate 8 [Member] | Unallocated Financing Receivables [Member]
Balance, end of period
Risk Rate 8 [Member]
Balance, end of period		$ 459	$ 459
Loans acquired		459	459
Consumer Portfolio Segment [Member] | Credit Card Receivable [Member]
Balance, end of period		167,803	177,288
Consumer Portfolio Segment [Member] | Other Loans [Member]
Balance, end of period		227,480	208,380
Consumer Portfolio Segment [Member]
Balance, end of period		395,283	385,668
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Balance, end of period		300,042	279,740
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member]
Balance, end of period		746,754	696,180
Commercial Real Estate Portfolio Segment [Member] | Other Commercial Loans [Member]
Balance, end of period		1,327,372	1,229,072
Commercial Real Estate Portfolio Segment [Member]
Balance, end of period		2,374,168	2,204,992
Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Balance, end of period		551,695	500,116
Commercial Portfolio Segment [Member] | Agricultural Loans [Member]
Balance, end of period		143,033	148,563
Commercial Portfolio Segment [Member]
Balance, end of period		694,728	648,679
Unallocated Financing Receivables [Member]
Balance, end of period		8,512	7,115
Balance, end of period		4,930,061	4,919,355
Loans acquired	[1]	$ 1,457,370	$ 1,672,901

[1] See Note 5, Loans Acquired, for segregation of loans acquired by loan class. In September 2015 the Company entered into an agreement with the FDIC to terminate all loss sharing agreements.