Note 5 - Loans and Allowance for Loan Losses - Nonaccrual Loans, Excluding Loans Acquired, Segregated by Class of Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Loans in nonaccrual status	$ 54,438	$ 39,104
Consumer Portfolio Segment [Member]
Loans in nonaccrual status	4,153	2,166
Consumer Portfolio Segment [Member] | Credit Card Receivable [Member]
Loans in nonaccrual status	273	373
Consumer Portfolio Segment [Member] | Other Loans [Member]
Loans in nonaccrual status	3,880	1,793
Commercial Real Estate Portfolio Segment [Member]
Loans in nonaccrual status	34,248	27,935
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans in nonaccrual status	2,403	3,411
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member]
Loans in nonaccrual status	13,034	12,139
Commercial Real Estate Portfolio Segment [Member] | Other Commercial Loans [Member]
Loans in nonaccrual status	18,811	12,385
Commercial Portfolio Segment [Member]
Loans in nonaccrual status	16,037	9,003
Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Loans in nonaccrual status	13,827	7,765
Commercial Portfolio Segment [Member] | Agricultural Loans [Member]
Loans in nonaccrual status	$ 2,210	$ 1,238