Note 7 - Loans (Details) - Portfolio by Risk Rating (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	$ 8,565,278	$ 8,084,563
Commercial Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	2,120,818	2,108,191
Commercial Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	120,796	84,786
Commercial Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	77,839	102,088
Commercial Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	3,427	3,659
Commercial Loans [Member] | Total [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	2,322,880	2,298,724
Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	2,322,880	2,298,724
Real Estate Construction Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	251,421	184,449
Real Estate Construction Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	32,418	33,939
Real Estate Construction Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	1,500	3,313
Real Estate Construction Loans [Member] | Total [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	285,339	221,701
Real Estate Construction Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	285,339	221,701
Commercial Mortgage Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	4,017,186	3,686,788
Commercial Mortgage Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	105,715	127,436
Commercial Mortgage Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	185,269	208,827
Commercial Mortgage Loans [Member] | Total [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	4,308,170	4,023,051
Commercial Mortgage Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	4,308,170	4,023,051
Residential Mortgage And Equity Lines Member | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	1,627,299	1,510,647
Residential Mortgage And Equity Lines Member | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	12,127	15,885
Residential Mortgage And Equity Lines Member | Total [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	1,639,426	1,526,532
Residential Mortgage And Equity Lines Member
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	1,639,426	1,526,532
Installment And Other Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	9,463	14,555
Installment And Other Loans [Member] | Total [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	9,463	14,555
Installment And Other Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	9,463	14,555
Total [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	8,026,187	7,504,630
Total [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	226,511	212,222
Total [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	307,653	360,739
Total [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	4,927	6,972
Total [Member] | Total [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	8,565,278	8,084,563
Total [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	$ 8,565,278	$ 8,084,563