Note 7 - Loans (Detail) - Portfolio by Risk Rating (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Gross Loans	$ 7,259,930	$ 7,059,212
Loans held for sale		760
Pass [Member] | Commercial Loans Member
Gross Loans	1,900,049	1,689,842
Pass [Member] | Real Estate Construction Loans [Member]
Gross Loans	114,649	115,538
Pass [Member] | Commercial Mortgage Loans [Member]
Gross Loans	3,276,291	3,275,431
Pass [Member] | Residential Mortgage And Equity Lines Member
Gross Loans	1,256,683	1,149,225
Pass [Member] | Installment And Other Loans Member
Gross Loans	11,702	17,636
Pass [Member] | Total [Member]
Gross Loans	6,559,374	6,247,672
Pass [Member]
Loans held for sale	0	0
Special Mention [Member] | Commercial Loans Member
Gross Loans	77,797	64,290
Special Mention [Member] | Real Estate Construction Loans [Member]
Gross Loans	21,718	23,555
Special Mention [Member] | Commercial Mortgage Loans [Member]
Gross Loans	165,415	69,925
Special Mention [Member] | Residential Mortgage And Equity Lines Member
Gross Loans	344	4,439
Special Mention [Member] | Installment And Other Loans Member
Gross Loans	0	63
Special Mention [Member] | Total [Member]
Gross Loans	265,274	162,272
Special Mention [Member]
Loans held for sale	0	0
Substandard [Member] | Commercial Loans Member
Gross Loans	90,684	108,858
Substandard [Member] | Real Estate Construction Loans [Member]
Gross Loans	43,022	90,132
Substandard [Member] | Commercial Mortgage Loans [Member]
Gross Loans	263,071	403,541
Substandard [Member] | Residential Mortgage And Equity Lines Member
Gross Loans	16,115	33,160
Substandard [Member] | Installment And Other Loans Member
Gross Loans	0	0
Substandard [Member] | Total [Member]
Gross Loans	412,892	635,691
Substandard [Member]
Loans held for sale	0	260
Doubtful [Member] | Commercial Loans Member
Gross Loans	14,390	5,285
Doubtful [Member] | Real Estate Construction Loans [Member]
Gross Loans	7,859	8,147
Doubtful [Member] | Commercial Mortgage Loans [Member]
Gross Loans	0	0
Doubtful [Member] | Residential Mortgage And Equity Lines Member
Gross Loans	141	145
Doubtful [Member] | Installment And Other Loans Member
Gross Loans	0	0
Doubtful [Member] | Total [Member]
Gross Loans	22,390	13,577
Doubtful [Member]
Loans held for sale	0	500
Total [Member] | Commercial Loans Member
Gross Loans	2,082,920	1,868,275
Total [Member] | Real Estate Construction Loans [Member]
Gross Loans	187,248	237,372
Total [Member] | Commercial Mortgage Loans [Member]
Gross Loans	3,704,777	3,748,897
Total [Member] | Residential Mortgage And Equity Lines Member
Gross Loans	1,273,283	1,186,969
Total [Member] | Installment And Other Loans Member
Gross Loans	11,702	17,699
Total [Member] | Total [Member]
Gross Loans	7,259,930	7,059,212
Total [Member]
Loans held for sale	0	760
Commercial Loans Member
Gross Loans	2,082,920	1,868,275
Real Estate Construction Loans [Member]
Gross Loans	187,248	237,372
Commercial Mortgage Loans [Member]
Gross Loans	3,704,777	3,748,897
Residential Mortgage And Equity Lines Member
Gross Loans	1,273,283	1,186,969
Installment And Other Loans Member
Gross Loans	11,702	17,699
Total [Member]
Gross Loans	$ 7,259,930	$ 7,059,212