Note 5 - Loans - Allowance for Loan Losses by Portfolio Segment and Based on Impairment Method (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loans individually evaluated for impairment, allowance	$ 2,134	$ 2,796
Loans individually evaluated for impairment, balance	117,353	115,074
Loans collectively evaluated for impairment, allowance	121,145	116,170
Loans collectively evaluated for impairment, balance	12,752,937	11,086,201
Loans, allowance	123,279	118,966
Loans	12,870,290	11,201,275
Commercial Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance	43	1,827
Loans individually evaluated for impairment, balance	43,495	27,761
Loans collectively evaluated for impairment, allowance	49,753	47,376
Loans collectively evaluated for impairment, balance	2,417,771	2,220,426
Loans, allowance	49,796	49,203
Loans	2,461,266	2,248,187
Real Estate Construction Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance
Loans individually evaluated for impairment, balance	8,185	5,458
Loans collectively evaluated for impairment, allowance	24,838	23,268
Loans collectively evaluated for impairment, balance	670,620	542,630
Loans, allowance	24,838	23,268
Loans	678,805	548,088
Commercial Real Estate Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance	1,738	573
Loans individually evaluated for impairment, balance	52,664	64,470
Loans collectively evaluated for impairment, allowance	35,872	34,291
Loans collectively evaluated for impairment, balance	6,430,031	5,720,778
Loans, allowance	37,610	34,864
Loans	6,482,695	5,785,248
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance	353	396
Loans individually evaluated for impairment, balance	13,009	17,385
Loans collectively evaluated for impairment, allowance	10,660	11,224
Loans collectively evaluated for impairment, balance	3,229,345	2,598,374
Loans, allowance	11,013	11,620
Loans	3,242,354	2,615,759
Consumer Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance
Loans individually evaluated for impairment, balance
Loans collectively evaluated for impairment, allowance	22	11
Loans collectively evaluated for impairment, balance	5,170	3,993
Loans, allowance	22	11
Loans	$ 5,170	$ 3,993

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

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

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

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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))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

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