Note 5 - Loans - Allowance for Loan Losses by Portfolio Segment and Based on Impairment Method (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Loans individually evaluated for impairment, allowance	$ 3,802	$ 2,134
Loans individually evaluated for impairment, balance	106,886	117,353
Loans collectively evaluated for impairment, allowance	118,589	121,145
Loans collectively evaluated for impairment, balance	13,888,902	12,752,937
Loans, allowance	122,391	123,279
Loans	13,995,788	12,870,290
Commercial Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance	1,837	43
Loans individually evaluated for impairment, balance	36,940	43,495
Loans collectively evaluated for impairment, allowance	53,141	49,753
Loans collectively evaluated for impairment, balance	2,705,025	2,417,771
Loans, allowance	54,978	49,796
Loans	2,741,965	2,461,266
Real Estate Construction Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance
Loans individually evaluated for impairment, balance	4,873	8,185
Loans collectively evaluated for impairment, allowance	19,626	24,838
Loans collectively evaluated for impairment, balance	576,581	670,620
Loans, allowance	19,626	24,838
Loans	581,454	678,805
Commercial Real Estate Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance	877	1,738
Loans individually evaluated for impairment, balance	51,471	52,664
Loans collectively evaluated for impairment, allowance	32,610	35,872
Loans collectively evaluated for impairment, balance	6,672,729	6,430,031
Loans, allowance	33,487	37,610
Loans	6,724,200	6,482,695
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance	1,088	353
Loans individually evaluated for impairment, balance	13,602	13,009
Loans collectively evaluated for impairment, allowance	13,194	10,660
Loans collectively evaluated for impairment, balance	3,930,218	3,229,345
Loans, allowance	14,282	11,013
Loans	3,943,820	3,242,354
Consumer Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance
Loans individually evaluated for impairment, balance
Loans collectively evaluated for impairment, allowance	18	22
Loans collectively evaluated for impairment, balance	4,349	5,170
Loans, allowance	18	22
Loans	$ 4,349	$ 5,170

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

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-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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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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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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