Note 5 - Loans Acquired (Details) - Age Analysis of Past Due Acquired Loans, Excluding Loans Covered by Loss Share (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Consumer:
Past due acquired loans, total loans	$ 4,640,000	$ 2,740,000
Other Consumer [Member] | Acquired Loans [Member]
Consumer:
Past due acquired loans, gross 30-89 days past due	296	70
Past due acquired loans, 90 days or more past due	91	34
Past due acquired loans, total past due	387	104
Past due acquired loans, current	130,779	8,407
Past due acquired loans, total loans	131,166	8,511
Past due acquired loans, 90 days past due and accruing	11	5
Other Consumer [Member]
Consumer:
Past due acquired loans, total loans	107,486	103,402
Consumer Loans [Member] | Acquired Loans [Member]
Consumer:
Past due acquired loans, gross 30-89 days past due	296	70
Past due acquired loans, 90 days or more past due	91	34
Past due acquired loans, total past due	387	104
Past due acquired loans, current	130,779	8,407
Past due acquired loans, total loans	131,166	8,511
Past due acquired loans, 90 days past due and accruing	11	5
Consumer Loans [Member]
Consumer:
Past due acquired loans, total loans	278,899	288,782
Construction Loans [Member] | Acquired Loans [Member]
Consumer:
Past due acquired loans, gross 30-89 days past due	604	292
Past due acquired loans, 90 days or more past due	111	105
Past due acquired loans, total past due	715	397
Past due acquired loans, current	149,015	36,450
Past due acquired loans, total loans	149,730	36,847
Construction Loans [Member]
Consumer:
Past due acquired loans, total loans	178,929	181,968
Single Family Residential Loans [Member] | Acquired Loans [Member]
Consumer:
Past due acquired loans, gross 30-89 days past due	5,179	3,804
Past due acquired loans, 90 days or more past due	4,522	2,906
Past due acquired loans, total past due	9,701	6,710
Past due acquired loans, current	679,850	138,383
Past due acquired loans, total loans	689,551	145,093
Past due acquired loans, 90 days past due and accruing	1,552	594
Single Family Residential Loans [Member]
Consumer:
Past due acquired loans, total loans	467,671	455,563
Other Commercial Loans [Member] | Acquired Loans [Member]
Consumer:
Past due acquired loans, gross 30-89 days past due	5,409	1,415
Past due acquired loans, 90 days or more past due	8,469	5,994
Past due acquired loans, total past due	13,878	7,409
Past due acquired loans, current	1,097,724	326,759
Past due acquired loans, total loans	1,111,601	334,168
Other Commercial Loans [Member]
Consumer:
Past due acquired loans, total loans	324,815	291,820
Real Estate Loans [Member] | Acquired Loans [Member]
Consumer:
Past due acquired loans, gross 30-89 days past due	11,192	5,511
Past due acquired loans, 90 days or more past due	13,102	9,005
Past due acquired loans, total past due	24,294	14,516
Past due acquired loans, current	1,926,588	501,592
Past due acquired loans, total loans	1,950,882	516,108
Past due acquired loans, 90 days past due and accruing	1,552	594
Real Estate Loans [Member]
Consumer:
Past due acquired loans, total loans	1,402,301	1,352,328
Commercial [Member] | Acquired Loans [Member]
Consumer:
Past due acquired loans, gross 30-89 days past due	2,509	110
Past due acquired loans, 90 days or more past due	1,221	421
Past due acquired loans, total past due	3,790	531
Past due acquired loans, current	303,172	46,730
Past due acquired loans, total loans	306,902	47,261
Past due acquired loans, 90 days past due and accruing	186
Agricultural Loans [Member] | Acquired Loans [Member]
Consumer:
Past due acquired loans, gross 30-89 days past due	1,089
Past due acquired loans, total past due	1,089
Past due acquired loans, current	21,447	4,100
Past due acquired loans, total loans	22,536	4,100
Agricultural Loans [Member]
Consumer:
Past due acquired loans, total loans	105,228	115,658
Commercial Loans [Member] | Acquired Loans [Member]
Consumer:
Past due acquired loans, gross 30-89 days past due	3,598	110
Past due acquired loans, 90 days or more past due	1,221	421
Past due acquired loans, total past due	4,819	531
Past due acquired loans, current	324,619	51,360
Past due acquired loans, total loans	329,438	51,361
Past due acquired loans, 90 days past due and accruing	186
Commercial Loans [Member]
Consumer:
Past due acquired loans, total loans	430,043	407,478
Other Loans [Member] | Acquired Loans [Member]
Consumer:
Past due acquired loans, current	6,954
Past due acquired loans, total loans	6,954
Other Loans [Member]
Consumer:
Past due acquired loans, total loans	4,137	5,133
Total Loans [Member] | Acquired Loans [Member]
Consumer:
Past due acquired loans, gross 30-89 days past due	15,086	5,691
Past due acquired loans, 90 days or more past due	14,414	9,460
Past due acquired loans, total past due	29,500	15,151
Past due acquired loans, current	2,388,940	560,829
Past due acquired loans, total loans	2,418,440	575,980
Past due acquired loans, 90 days past due and accruing	$ 1,749	$ 599