Note 7 - Loans (Details) - Allowance for Loan Losses by Portfolio Segment and Based on Impairment Method (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Loans individually evaluated for impairment
Loans individually evaluated for impairment, allowance	$ 11,044	$ 11,798
Loans individually evaluated for impairment, balance	180,717	174,519
Loans collectively evaluated for impairment
Loans collectively evaluated for impairment, allowance	145,045	149,622
Loans collectively evaluated for impairment, balance	9,044,080	8,739,561
Loans, allowance	156,089	161,420
Loans	9,224,797	8,914,080
Commercial Loans [Member]
Loans individually evaluated for impairment
Loans individually evaluated for impairment, allowance	3,911	1,263
Loans individually evaluated for impairment, balance	28,808	23,489
Loans collectively evaluated for impairment
Loans collectively evaluated for impairment, allowance	45,794	46,238
Loans collectively evaluated for impairment, balance	2,405,742	2,359,004
Loans, allowance	49,705	47,501
Loans	2,434,550	2,382,493
Real Estate Construction Loans [Member]
Loans individually evaluated for impairment
Loans individually evaluated for impairment, allowance		1,077
Loans individually evaluated for impairment, balance	22,873	25,728
Loans collectively evaluated for impairment
Loans collectively evaluated for impairment, allowance	23,270	26,575
Loans collectively evaluated for impairment, balance	322,687	272,926
Loans, allowance	23,270	27,652
Loans	345,560	298,654
Commercial Mortgage Loans [Member]
Loans individually evaluated for impairment
Loans individually evaluated for impairment, allowance	6,635	8,993
Loans individually evaluated for impairment, balance	111,724	109,194
Loans collectively evaluated for impairment
Loans collectively evaluated for impairment, allowance	64,683	65,680
Loans collectively evaluated for impairment, balance	4,551,327	4,377,249
Loans, allowance	71,318	74,673
Loans	4,663,051	4,486,443
Residential Mortgage and Equity Lines [Member]
Loans individually evaluated for impairment
Loans individually evaluated for impairment, allowance	498	465
Loans individually evaluated for impairment, balance	17,312	16,108
Loans collectively evaluated for impairment
Loans collectively evaluated for impairment, allowance	11,279	11,113
Loans collectively evaluated for impairment, balance	1,758,954	1,726,830
Loans, allowance	11,777	11,578
Loans	1,776,266	1,742,938
Installment And Other Loans [Member]
Loans collectively evaluated for impairment
Loans collectively evaluated for impairment, allowance	19	16
Loans collectively evaluated for impairment, balance	5,370	3,552
Loans, allowance	19	16
Loans	$ 5,370	$ 3,552

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- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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The balance of financing receivables that were collectively evaluated for impairment.

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-Publisher FASB

-Name Accounting Standards Codification

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The balance of financing receivables that were individually evaluated for impairment.

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-Publisher FASB

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-Topic 310

-SubTopic 10

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-Paragraph 11B

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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(d))

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-Number 210

-Section 03

-Paragraph 7

-Subparagraph d

-Article 9

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-Name Staff Accounting Bulletin (SAB)

-Number Topic 6

-Section L

-Subsection 1

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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.

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