Note 5 - Loans and Allowance for Credit Losses (Detail) - Loans by delinquency and nonaccrual status (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
30-89 Days Past Due and Accruing	$ 40,704	$ 71,391
Past Due 90 days or More and Accruing	1,073	1,122
Total Past Due and Accruing	41,777	72,513
Current and Accruing	2,534,202	2,742,395
Nonaccrual	58,860	107,176
Total Loans	2,634,839	2,922,084
Commercial [Member]
30-89 Days Past Due and Accruing	4,077	7,274
Total Past Due and Accruing	4,077	7,274
Current and Accruing	409,805	458,061
Nonaccrual	5,520	8,848
Total Loans	419,402	474,183
Commercial Real Estate Loans [Member]
30-89 Days Past Due and Accruing	13,253	14,037
Total Past Due and Accruing	13,253	14,037
Current and Accruing	702,604	737,167
Nonaccrual	5,083	5,936
Total Loans	720,940	757,140
Construction [Member]
30-89 Days Past Due and Accruing		4,022
Total Past Due and Accruing		4,022
Current and Accruing	14,224	18,073
Nonaccrual	4,022	4,050
Total Loans	18,246	26,145
Residential Real Estate Loans [Member]
30-89 Days Past Due and Accruing	4,191	2,552
Total Past Due and Accruing	4,191	2,552
Current and Accruing	277,138	305,709
Nonaccrual	2,492	1,935
Total Loans	283,821	310,196
Consumer Installment And Other [Member]
30-89 Days Past Due and Accruing	4,632	6,870
Past Due 90 days or More and Accruing	794	766
Total Past Due and Accruing	5,426	7,636
Current and Accruing	472,270	454,142
Nonaccrual	181	99
Total Loans	477,877	461,877
Originated Loans [Member]
30-89 Days Past Due and Accruing	26,153	34,755
Past Due 90 days or More and Accruing	794	766
Total Past Due and Accruing	26,947	35,521
Current and Accruing	1,876,041	1,973,152
Nonaccrual	17,298	20,868
Total Loans	1,920,286	2,029,541
Purchased Non-Covered Loans [Member]
30-89 Days Past Due and Accruing	4,375	8,788
Past Due 90 days or More and Accruing		1
Total Past Due and Accruing	4,375	8,789
Current and Accruing	109,284	151,619
Nonaccrual	25,541	39,163
Total Loans	139,200	199,571
Purchased Covered Loans [Member]
30-89 Days Past Due and Accruing	10,176	27,848
Past Due 90 days or More and Accruing	279	355
Total Past Due and Accruing	10,455	28,203
Current and Accruing	548,877	617,624
Nonaccrual	16,021	47,145
Total Loans	$ 575,353	$ 692,972