Note 7 - Loans (Detail) - Portfolio by Risk Rating (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Gross Loans	$ 7,043,683	$ 7,059,212
Loans held for sale	500	760
Pass [Member] | Commercial Loans Member
Gross Loans	1,779,114	1,689,842
Pass [Member] | Real Estate Construction Loans [Member]
Gross Loans	107,217	115,538
Pass [Member] | Commercial Mortgage Loans [Member]
Gross Loans	3,266,362	3,275,431
Pass [Member] | Residential Mortgage And Equity Lines Member
Gross Loans	1,188,160	1,149,225
Pass [Member] | Installment And Other Loans Member
Gross Loans	16,673	17,636
Pass [Member] | Total [Member]
Gross Loans	6,357,526	6,247,672
Special Mention [Member] | Commercial Loans Member
Gross Loans	61,298	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	138,544	69,925
Special Mention [Member] | Residential Mortgage And Equity Lines Member
Gross Loans		4,439
Special Mention [Member] | Installment And Other Loans Member
Gross Loans		63
Special Mention [Member] | Total [Member]
Gross Loans	221,560	162,272
Special Mention [Member]
Loans held for sale	0
Substandard [Member] | Commercial Loans Member
Gross Loans	91,940	108,858
Substandard [Member] | Real Estate Construction Loans [Member]
Gross Loans	44,033	90,132
Substandard [Member] | Commercial Mortgage Loans [Member]
Gross Loans	290,534	403,541
Substandard [Member] | Residential Mortgage And Equity Lines Member
Gross Loans	17,390	33,160
Substandard [Member] | Installment And Other Loans Member
Gross Loans	0
Substandard [Member] | Total [Member]
Gross Loans	443,897	635,691
Substandard [Member]
Loans held for sale	0	260
Doubtful [Member] | Commercial Loans Member
Gross Loans	13,368	5,285
Doubtful [Member] | Real Estate Construction Loans [Member]
Gross Loans	7,118	8,147
Doubtful [Member] | Commercial Mortgage Loans [Member]
Gross Loans	0
Doubtful [Member] | Residential Mortgage And Equity Lines Member
Gross Loans	214	145
Doubtful [Member] | Installment And Other Loans Member
Gross Loans	0
Doubtful [Member] | Total [Member]
Gross Loans	20,700	13,577
Doubtful [Member]
Loans held for sale	500	500
Total [Member] | Commercial Loans Member
Gross Loans	1,945,720	1,868,275
Total [Member] | Real Estate Construction Loans [Member]
Gross Loans	180,086	237,372
Total [Member] | Commercial Mortgage Loans [Member]
Gross Loans	3,695,440	3,748,897
Total [Member] | Residential Mortgage And Equity Lines Member
Gross Loans	1,205,764	1,186,969
Total [Member] | Installment And Other Loans Member
Gross Loans	16,673	17,699
Total [Member] | Total [Member]
Gross Loans	7,043,683	7,059,212
Total [Member]
Loans held for sale	500	760
Commercial Loans Member
Gross Loans	1,945,720	1,868,275
Real Estate Construction Loans [Member]
Gross Loans	180,086	237,372
Commercial Mortgage Loans [Member]
Gross Loans	3,695,440	3,748,897
Residential Mortgage And Equity Lines Member
Gross Loans	1,205,764	1,186,969
Installment And Other Loans Member
Gross Loans	16,673	17,699
Total [Member]
Gross Loans	$ 7,043,683	$ 7,059,212