Note 4 - Loans and Allowance for Loan Losses (Details) - Loan Portfolio by Categories (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Consumer:
Loans	$ 2,740,000	$ 2,400,000
Loans acquired, not covered by FDIC loss share (net of discount)	575,980	515,644
Loans acquired, covered by FDIC loss share (net of discount and allowance)	106,933	146,653
Credit Cards [Member]
Consumer:
Loans	185,380	184,935
Student Loans [Member]
Consumer:
Loans		25,906
Other Consumer [Member]
Consumer:
Loans	103,402	98,851
Consumer Loans [Member]
Consumer:
Loans	288,782	309,692
Construction Loans [Member]
Consumer:
Loans	181,968	146,458
Single Family Residential Loans [Member]
Consumer:
Loans	455,563	392,285
Other Commercial Real Estate Loans [Member]
Consumer:
Loans	714,797	626,333
Real Estate Loans [Member]
Consumer:
Loans	1,352,328	1,165,076
Other Commercial Loans [Member]
Consumer:
Loans	291,820	164,329
Agricultural Loans [Member]
Consumer:
Loans	115,658	98,886
Commercial Loans [Member]
Consumer:
Loans	407,478	263,215
Other Loans [Member]
Consumer:
Loans	5,133	4,655
Loans, excluding acquired loans [Member]
Consumer:
Loans	2,053,721	1,742,638
Loans, Including Acquired Loans [Member]
Consumer:
Total loans	$ 2,736,634	$ 2,404,935