Note 7 - Loans (Details) - Portfolio by Risk Rating (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	$ 7,694,373	$ 7,429,147
Commercial Loans Member | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	2,015,694	1,944,989
Commercial Loans Member | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	100,317	76,776
Commercial Loans Member | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	90,936	94,077
Commercial Loans Member | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	3,814	11,265
Commercial Loans Member | Total [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	2,210,761	2,127,107
Commercial Loans Member
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	2,210,761	2,127,107
Real Estate Construction Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	115,033	109,269
Real Estate Construction Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	0	18,000
Real Estate Construction Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	36,382	45,171
Real Estate Construction Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	2,248	8,510
Real Estate Construction Loans [Member] | Total [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	153,663	180,950
Real Estate Construction Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	153,663	180,950
Commercial Mortgage Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	3,495,985	3,344,783
Commercial Mortgage Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	150,281	162,455
Commercial Mortgage Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	263,052	261,214
Commercial Mortgage Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	241	0
Commercial Mortgage Loans [Member] | Total [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	3,909,559	3,768,452
Commercial Mortgage Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	3,909,559	3,768,452
Residential Mortgage And Equity Lines Member | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	1,392,746	1,322,768
Residential Mortgage And Equity Lines Member | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	708	816
Residential Mortgage And Equity Lines Member | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	13,976	16,084
Residential Mortgage And Equity Lines Member | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	117	414
Residential Mortgage And Equity Lines Member | Total [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	1,407,547	1,340,082
Residential Mortgage And Equity Lines Member
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	1,407,547	1,340,082
Installment And Other Loans Member | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	12,843	12,556
Installment And Other Loans Member | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	0	0
Installment And Other Loans Member | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	0	0
Installment And Other Loans Member | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	0	0
Installment And Other Loans Member | Total [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	12,843	12,556
Installment And Other Loans Member
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	12,843	12,556
Total [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	7,032,301	6,734,365
Total [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	251,306	258,047
Total [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	404,346	416,546
Total [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	6,420	20,189
Total [Member] | Total [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	7,694,373	7,429,147
Total [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	$ 7,694,373	$ 7,429,147