Note 5 - Loans Acquired (Details) - Carrying Value of all Acquired Impaired Loans - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
Note 5 - Loans Acquired (Details) - Carrying Value of all Acquired Impaired Loans [Line Items]
Acquired loans	[1]	$ 2,013,816	$ 682,913
Consumer Portfolio Segment [Member]
Note 5 - Loans Acquired (Details) - Carrying Value of all Acquired Impaired Loans [Line Items]
Acquired loans		100,080	8,514
Consumer Portfolio Segment [Member] | Other Loans [Member]
Note 5 - Loans Acquired (Details) - Carrying Value of all Acquired Impaired Loans [Line Items]
Acquired loans		100,080	8,514
Commercial Real Estate Portfolio Segment [Member]
Note 5 - Loans Acquired (Details) - Carrying Value of all Acquired Impaired Loans [Line Items]
Acquired loans		1,723,164	613,758
Commercial Real Estate Portfolio Segment [Member] | Other Loans [Member]
Note 5 - Loans Acquired (Details) - Carrying Value of all Acquired Impaired Loans [Line Items]
Acquired loans		988,831	390,877
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Note 5 - Loans Acquired (Details) - Carrying Value of all Acquired Impaired Loans [Line Items]
Acquired loans		116,302	46,911
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member]
Note 5 - Loans Acquired (Details) - Carrying Value of all Acquired Impaired Loans [Line Items]
Acquired loans		618,031	175,970
Commercial Portfolio Segment [Member]
Note 5 - Loans Acquired (Details) - Carrying Value of all Acquired Impaired Loans [Line Items]
Acquired loans		190,572	60,641
Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Note 5 - Loans Acquired (Details) - Carrying Value of all Acquired Impaired Loans [Line Items]
Acquired loans		164,942	56,134
Commercial Portfolio Segment [Member] | Agricultural Loans [Member]
Note 5 - Loans Acquired (Details) - Carrying Value of all Acquired Impaired Loans [Line Items]
Acquired loans		25,630	4,507
Unallocated Financing Receivables [Member]
Note 5 - Loans Acquired (Details) - Carrying Value of all Acquired Impaired Loans [Line Items]
Acquired loans		$ 0	$ 0

[1] Loans acquired are reported net of a $954,000 allowance at September 30, 2015. Loans acquired include $106.9 million (net of a $954,000 allowance) of loans covered by FDIC loss share agreements at December 31, 2014.