Note 4 - Loans and Allowance for Credit Losses (Detail) - Credit risk profile by internally assigned grade (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Grade:
Loans by grade	$ 2,111,357	$ 2,523,806
Pass [Member] | Commercial [Member]
Grade:
Loans by grade	324,452	377,526
Pass [Member] | Commercial Real Estate Loans [Member]
Grade:
Loans by grade	599,472	675,181
Pass [Member] | Construction [Member]
Grade:
Loans by grade	7,518	10,754
Pass [Member] | Residential Real Estate Loans [Member]
Grade:
Loans by grade	219,655	266,822
Pass [Member] | Consumer Installment And Other [Member]
Grade:
Loans by grade	459,076	472,383
Pass [Member] | Purchased Non-Covered Loans [Member]
Grade:
Loans by grade	51,901	79,656
Pass [Member] | Purchased Covered Loans [Member]
Grade:
Loans by grade	274,976	404,925
Pass [Member]
Grade:
Loans by grade	1,937,050	2,287,247
Substandard [Member] | Commercial [Member]
Grade:
Loans by grade	11,413	20,695
Substandard [Member] | Commercial Real Estate Loans [Member]
Grade:
Loans by grade	33,455	29,474
Substandard [Member] | Construction [Member]
Grade:
Loans by grade	466	3,826
Substandard [Member] | Residential Real Estate Loans [Member]
Grade:
Loans by grade	2,803	4,289
Substandard [Member] | Consumer Installment And Other [Member]
Grade:
Loans by grade	1,158	1,014
Substandard [Member] | Purchased Non-Covered Loans [Member]
Grade:
Loans by grade	27,066	52,994
Substandard [Member] | Purchased Covered Loans [Member]
Grade:
Loans by grade	122,815	175,410
Substandard [Member]
Grade:
Loans by grade	199,176	287,702
Doubtful [Member] | Commercial [Member]
Grade:
Loans by grade	4,251	225
Doubtful [Member] | Consumer Installment And Other [Member]
Grade:
Loans by grade	46	66
Doubtful [Member] | Purchased Non-Covered Loans [Member]
Grade:
Loans by grade	1,145	3,444
Doubtful [Member] | Purchased Covered Loans [Member]
Grade:
Loans by grade	470	1,070
Doubtful [Member]
Grade:
Loans by grade	5,912	4,805
Unlikely to be Collected Financing Receivable [Member] | Consumer Installment And Other [Member]
Grade:
Loans by grade	418	352
Unlikely to be Collected Financing Receivable [Member] | Purchased Non-Covered Loans [Member]
Grade:
Loans by grade	5	38
Unlikely to be Collected Financing Receivable [Member] | Purchased Covered Loans [Member]
Grade:
Loans by grade	150	155
Unlikely to be Collected Financing Receivable [Member]
Grade:
Loans by grade	573	545
Default Risk Purchase Discount [Member] | Purchased Non-Covered Loans [Member]
Grade:
Loans by grade	(5,226)	(10,211)
Default Risk Purchase Discount [Member] | Purchased Covered Loans [Member]
Grade:
Loans by grade	(26,128)	(46,282)
Default Risk Purchase Discount [Member]
Grade:
Loans by grade	(31,354)	(56,493)
Commercial [Member]
Grade:
Loans by grade	340,116	398,446
Commercial Real Estate Loans [Member]
Grade:
Loans by grade	632,927	704,655
Construction [Member]
Grade:
Loans by grade	7,984	14,580
Residential Real Estate Loans [Member]
Grade:
Loans by grade	222,458	271,111
Consumer Installment And Other [Member]
Grade:
Loans by grade	460,698	473,815
Purchased Non-Covered Loans [Member]
Grade:
Loans by grade	74,891	125,921
Purchased Covered Loans [Member]
Grade:
Loans by grade	$ 372,283	$ 535,278