Note 5 - Loans (Detail) - Portfolio by Risk Rating (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Gross Loans	$ 7,429,147	$ 7,059,212
Loans held for sale		760
Pass [Member] | Commercial Loans Member
Gross Loans	1,944,989	1,689,842
Pass [Member] | Real Estate Construction Loans [Member]
Gross Loans	109,269	115,538
Pass [Member] | Commercial Mortgage Loans [Member]
Gross Loans	3,344,783	3,275,431
Pass [Member] | Residential Mortgage And Equity Lines Member
Gross Loans	1,322,768	1,149,225
Pass [Member] | Installment And Other Loans Member
Gross Loans	12,556	17,636
Pass [Member] | Total [Member]
Gross Loans	6,734,365	6,247,672
Pass [Member]
Loans held for sale		0
Special Mention [Member] | Commercial Loans Member
Gross Loans	76,776	64,290
Special Mention [Member] | Real Estate Construction Loans [Member]
Gross Loans	18,000	23,555
Special Mention [Member] | Commercial Mortgage Loans [Member]
Gross Loans	162,455	69,925
Special Mention [Member] | Residential Mortgage And Equity Lines Member
Gross Loans	816	4,439
Special Mention [Member] | Installment And Other Loans Member
Gross Loans	0	63
Special Mention [Member] | Total [Member]
Gross Loans	258,047	162,272
Special Mention [Member]
Loans held for sale		0
Substandard [Member] | Commercial Loans Member
Gross Loans	94,077	108,858
Substandard [Member] | Real Estate Construction Loans [Member]
Gross Loans	45,171	90,132
Substandard [Member] | Commercial Mortgage Loans [Member]
Gross Loans	261,214	403,541
Substandard [Member] | Residential Mortgage And Equity Lines Member
Gross Loans	16,084	33,160
Substandard [Member] | Installment And Other Loans Member
Gross Loans	0	0
Substandard [Member] | Total [Member]
Gross Loans	416,546	635,691
Substandard [Member]
Loans held for sale		260
Doubtful [Member] | Commercial Loans Member
Gross Loans	11,265	5,285
Doubtful [Member] | Real Estate Construction Loans [Member]
Gross Loans	8,510	8,147
Doubtful [Member] | Commercial Mortgage Loans [Member]
Gross Loans	0	0
Doubtful [Member] | Residential Mortgage And Equity Lines Member
Gross Loans	414	145
Doubtful [Member] | Installment And Other Loans Member
Gross Loans	0	0
Doubtful [Member] | Total [Member]
Gross Loans	20,189	13,577
Doubtful [Member]
Loans held for sale		500
Total [Member] | Commercial Loans Member
Gross Loans	2,127,107	1,868,275
Total [Member] | Real Estate Construction Loans [Member]
Gross Loans	180,950	237,372
Total [Member] | Commercial Mortgage Loans [Member]
Gross Loans	3,768,452	3,748,897
Total [Member] | Residential Mortgage And Equity Lines Member
Gross Loans	1,340,082	1,186,969
Total [Member] | Installment And Other Loans Member
Gross Loans	12,556	17,699
Total [Member] | Total [Member]
Gross Loans	7,429,147	7,059,212
Total [Member]
Loans held for sale		760
Commercial Loans Member
Gross Loans	2,127,107	1,868,275
Real Estate Construction Loans [Member]
Gross Loans	180,950	237,372
Commercial Mortgage Loans [Member]
Gross Loans	3,768,452	3,748,897
Residential Mortgage And Equity Lines Member
Gross Loans	1,340,082	1,186,969
Installment And Other Loans Member
Gross Loans	12,556	17,699
Total [Member]
Gross Loans	$ 7,429,147	$ 7,059,212