Note 4 - Loans and Allowance for Loan Losses (Details) - Loan Portfolio by Categories - USD ($) $ in Thousands		Jun. 30, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		$ 4,810,000	$ 2,740,000
Loans acquired, not covered by FDIC loss share (net of discount) (1)	[1]	2,108,306	575,980
Loans acquired, covered by FDIC loss share (net of discount and allowance) (1)	[1]	93,121	106,933
Total loans		4,812,656	2,736,634
Loans, Excluding Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		2,611,229	2,053,721
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		334,902	288,782
Consumer Portfolio Segment [Member] | Credit Card Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		174,074	185,380
Consumer Portfolio Segment [Member] | Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		160,828	103,402
Consumer Portfolio Segment [Member] | Loans, Excluding Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		334,902	288,782
Consumer Portfolio Segment [Member] | Loans, Excluding Acquired Loans [Member] | Credit Card Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		174,074	185,380
Consumer Portfolio Segment [Member] | Loans, Excluding Acquired Loans [Member] | Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		160,828	103,402
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		1,740,770	1,352,328
Commercial Real Estate Portfolio Segment [Member] | Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		878,109	714,797
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		199,707	181,968
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		662,954	455,563
Commercial Real Estate Portfolio Segment [Member] | Loans, Excluding Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		1,740,770	1,352,328
Commercial Real Estate Portfolio Segment [Member] | Loans, Excluding Acquired Loans [Member] | Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		878,109	714,797
Commercial Real Estate Portfolio Segment [Member] | Loans, Excluding Acquired Loans [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		199,707	181,968
Commercial Real Estate Portfolio Segment [Member] | Loans, Excluding Acquired Loans [Member] | Single Family Residential Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		662,954	455,563
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		530,371	407,478
Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		388,869	291,820
Commercial Portfolio Segment [Member] | Agricultural Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		141,502	115,658
Commercial Portfolio Segment [Member] | Loans, Excluding Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		530,371	407,478
Commercial Portfolio Segment [Member] | Loans, Excluding Acquired Loans [Member] | Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		388,869	291,820
Commercial Portfolio Segment [Member] | Loans, Excluding Acquired Loans [Member] | Agricultural Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		141,502	115,658
Unallocated Financing Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		5,186	5,133
Unallocated Financing Receivables [Member] | Loans, Excluding Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		$ 5,186	$ 5,133

[1] See Note 5, Loans Acquired, for segregation of loans acquired by loan class.