Note 5 - Loans and Allowance for Credit Losses (Details) - Loans Past Due (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	$ 9,055	$ 4,703
Loans 60-89 Days Past Due	8,600	11,068
Loans 90 Days or More Past Due	19,572	22,443
Total Past Due Loans	37,227	38,214
Current Loans	4,407,666	4,274,185
Total Recorded Investment in Loans	4,444,893us-gaap_NotesReceivableNet	4,312,399us-gaap_NotesReceivableNet
Commercial Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	3,356	1,505
Loans 60-89 Days Past Due	2,259	4,032
Loans 90 Days or More Past Due	11,257	12,975
Total Past Due Loans	16,872	18,512
Current Loans	916,843	897,714
Total Recorded Investment in Loans	933,715	916,226
Commercial Real Estate Investment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	2,425	1,825
Loans 60-89 Days Past Due	5,577	5,376
Loans 90 Days or More Past Due	2,152	2,645
Total Past Due Loans	10,154	9,846
Current Loans	1,729,329	1,693,326
Total Recorded Investment in Loans	1,739,483	1,703,172
Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	1,808	1,089
Loans 60-89 Days Past Due		214
Loans 90 Days or More Past Due	1,314	1,324
Total Past Due Loans	3,122	2,627
Current Loans	489,881	458,954
Total Recorded Investment in Loans	493,003	461,581
Real Estate Mortgage Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	444
Loans 90 Days or More Past Due	342	346
Total Past Due Loans	786	346
Current Loans	147,085	147,672
Total Recorded Investment in Loans	147,871	148,018
Home Equity Line of Credit [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	850
Loans 60-89 Days Past Due	641	1,365
Loans 90 Days or More Past Due	889	1,398
Total Past Due Loans	2,380	2,763
Current Loans	118,163	119,773
Total Recorded Investment in Loans	120,543	122,536
Consumer, Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	172	284
Loans 60-89 Days Past Due	123	81
Loans 90 Days or More Past Due	10	58
Total Past Due Loans	305	423
Current Loans	98,402	108,979
Total Recorded Investment in Loans	98,707	109,402
Construction Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 90 Days or More Past Due	3,608	3,697
Total Past Due Loans	3,608	3,697
Current Loans	907,963	847,767
Total Recorded Investment in Loans	$ 911,571	$ 851,464

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

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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- Definition

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

+ References

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- Definition

Recorded investment in financing receivables that are 90 days or more past due and still accruing.

+ 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)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5111-111524

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Financing receivables that are current.

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

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- Definition

Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.3)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 3

-Article 5

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