Note 5 - Loans - Aging of Loan Portfolio (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Loans past due	$ 126,826	$ 78,466
Non-accrual loans	49,682	52,130
Loans not past due	11,074,449	10,084,986
Loans	11,201,275	10,163,452
Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	43,419	22,854
Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	33,725	3,482
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due
Commercial Portfolio Segment [Member]
Loans past due	65,653	12,133
Non-accrual loans	15,710	3,545
Loans not past due	2,182,534	2,304,730
Loans	2,248,187	2,316,863
Commercial Portfolio Segment [Member] \| Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	22,753	8,367
Commercial Portfolio Segment [Member] \| Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	27,190	221
Commercial Portfolio Segment [Member] \| Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due
Real Estate Construction Portfolio Segment [Member]
Loans past due	21,683	23,591
Non-accrual loans	5,458	16,306
Loans not past due	526,405	417,952
Loans	548,088	441,543
Real Estate Construction Portfolio Segment [Member] \| Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	10,390	7,285
Real Estate Construction Portfolio Segment [Member] \| Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	5,835
Real Estate Construction Portfolio Segment [Member] \| Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due
Commercial Real Estate Portfolio Segment [Member]
Loans past due	26,664	29,697
Non-accrual loans	20,078	25,231
Loans not past due	5,758,584	5,271,521
Loans	5,785,248	5,301,218
Commercial Real Estate Portfolio Segment [Member] \| Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	5,886	2,243
Commercial Real Estate Portfolio Segment [Member] \| Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	700	2,223
Commercial Real Estate Portfolio Segment [Member] \| Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans past due	12,826	13,045
Non-accrual loans	8,436	7,048
Loans not past due	2,602,933	2,088,290
Loans	2,615,759	2,101,335
Residential Mortgage and Equity Lines Portfolio Segment [Member] \| Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	4,390	4,959
Residential Mortgage and Equity Lines Portfolio Segment [Member] \| Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due		1,038
Residential Mortgage and Equity Lines Portfolio Segment [Member] \| Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due
Consumer Portfolio Segment [Member]
Loans past due
Non-accrual loans
Loans not past due	3,993	2,493
Loans	3,993	2,493
Consumer Portfolio Segment [Member] \| Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due
Consumer Portfolio Segment [Member] \| Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due
Consumer Portfolio Segment [Member] \| Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due

Financing receivables that are current.

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=66008989&loc=SL6953401-111524

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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
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

Reference 2: 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=66008989&loc=d3e5111-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

Reference 2: 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=66008989&loc=SL6953401-111524

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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.

+ 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=65884687&loc=d3e4428-111522

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