Note 5 - Loans (Details) - Aging of Loan Portfolio (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, 30-59 Days Past Due	$ 36,359	$ 30,821
Loans, 60-89 Days Past Due	5,879	25,256
Loans, Greater than 90 Days Past Due		982
Non-accrual Loans	70,163	83,183
Loans, Past Due	112,401	140,242
Loans, Not Past Due	8,801,679	7,944,321
Loans	8,914,080	8,084,563
Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, 30-59 Days Past Due	11,595	7,170
Loans, 60-89 Days Past Due	1,238	16,562
Non-accrual Loans	6,983	21,232
Loans, Past Due	19,816	44,964
Loans, Not Past Due	2,362,677	2,253,760
Loans	2,382,493	2,298,724
Real Estate Construction Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, 30-59 Days Past Due	1,416
Non-accrual Loans	19,963	28,586
Loans, Past Due	21,379	28,586
Loans, Not Past Due	277,275	193,115
Loans	298,654	221,701
Commercial Mortgage Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, 30-59 Days Past Due	17,654	20,043
Loans, 60-89 Days Past Due	3,909	7,862
Loans, Greater than 90 Days Past Due		982
Non-accrual Loans	35,606	19,621
Loans, Past Due	57,169	48,508
Loans, Not Past Due	4,429,274	3,974,543
Loans	4,486,443	4,023,051
Residential Mortgage And Equity Lines Member
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, 30-59 Days Past Due	5,634	3,508
Loans, 60-89 Days Past Due	732	832
Non-accrual Loans	7,611	13,744
Loans, Past Due	13,977	18,084
Loans, Not Past Due	1,728,961	1,508,448
Loans	1,742,938	1,526,532
Installment And Other Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, 30-59 Days Past Due	60	100
Loans, Past Due	60	100
Loans, Not Past Due	3,492	14,455
Loans	$ 3,552	$ 14,555

Financing Receivable Recorded Investment Not In Past Due

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- Definition

Financing receivables that are less than 60 days past due but more than 29 days past due.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7A

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953401-111524

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Financing receivables that are less than 90 days past due but more than 59 days past due.

+ References

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Financing receivables that are equal to or greater than 90 days past due.

+ References

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- Definition

Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7

-Subparagraph (d)

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Recorded Investment in financing receivables that are past due at the balance sheet date.

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- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

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