Note 4 - Loans and Allowance for Loan Losses (Details) - Loans by Credit Risk Rating, Segregated by Class of Loans - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 4,812,656	$ 2,736,634
Loans acquired, not covered by FDIC loss share	2,108,306	575,980
Loans acquired, covered by FDIC loss share	93,121	106,933
Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	4,687,201	2,642,549
Loans acquired, not covered by FDIC loss share	2,046,360	535,728
Loans acquired, covered by FDIC loss share	93,121	106,933
Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	23,311	11,938
Loans acquired, not covered by FDIC loss share	13,901	1,435
Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	100,029	80,152
Loans acquired, not covered by FDIC loss share	46,151	36,958
Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	2,076	1,990
Loans acquired, not covered by FDIC loss share	1,855	1,854
Risk Rate 8 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	39	5
Loans acquired, not covered by FDIC loss share	39	5
Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	334,902	288,782
Consumer Portfolio Segment [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	333,838	287,438
Consumer Portfolio Segment [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		5
Consumer Portfolio Segment [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,056	1,296
Consumer Portfolio Segment [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	8	43
Consumer Portfolio Segment [Member] | Credit Card Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	174,074	185,380
Consumer Portfolio Segment [Member] | Credit Card Receivable [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	173,595	184,923
Consumer Portfolio Segment [Member] | Credit Card Receivable [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	479	457
Consumer Portfolio Segment [Member] | Other Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	160,828	103,402
Consumer Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	160,243	102,515
Consumer Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		5
Consumer Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	577	839
Consumer Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	8	43
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,740,770	1,352,328
Commercial Real Estate Portfolio Segment [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,690,959	1,321,194
Commercial Real Estate Portfolio Segment [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	7,336	8,934
Commercial Real Estate Portfolio Segment [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	42,300	22,118
Commercial Real Estate Portfolio Segment [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	175	82
Commercial Real Estate Portfolio Segment [Member] | Other Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	878,109	714,797
Commercial Real Estate Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	846,907	698,329
Commercial Real Estate Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	5,206	7,074
Commercial Real Estate Portfolio Segment [Member] | Other Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	25,996	9,394
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	199,707	181,968
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	192,697	176,825
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	514	84
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	6,496	5,059
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	662,954	455,563
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	651,355	446,040
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,616	1,776
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	9,808	7,665
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	175	82
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	530,371	407,478
Commercial Portfolio Segment [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	517,775	386,123
Commercial Portfolio Segment [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	2,074	1,564
Commercial Portfolio Segment [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	10,484	19,780
Commercial Portfolio Segment [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	38	11
Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	388,869	291,820
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	377,144	271,017
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,374	1,544
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	10,313	19,248
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Risk Rate 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	38	11
Commercial Portfolio Segment [Member] | Agricultural Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	141,502	115,658
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	140,631	115,106
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Risk Rate 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	700	20
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	171	532
Unallocated Financing Receivables [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	5,186	5,133
Unallocated Financing Receivables [Member] | Risk Rate 1-4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	5,148	$ 5,133
Unallocated Financing Receivables [Member] | Risk Rate 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 38