Note 8 - Loans - Allowance for Loan Losses by Portfolio Segment and Based on Impairment Method (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Loans individually evaluated for impairment, allowance	$ 1,501	$ 3,802
Loans individually evaluated for impairment, balance	88,847	106,886
Loans collectively evaluated for impairment, allowance	124,407	118,589
Loans collectively evaluated for impairment, balance	14,639,707	13,888,902
Loans, allowance	125,908	122,391
Loans	14,728,554	13,995,788
Commercial Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance	744	1,837
Loans individually evaluated for impairment, balance	33,726	36,940
Loans collectively evaluated for impairment, allowance	57,805	53,141
Loans collectively evaluated for impairment, balance	2,634,335	2,705,025
Loans, allowance	58,549	54,978
Loans	2,668,061	2,741,965
Real Estate Construction Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance	0	0
Loans individually evaluated for impairment, balance	4,629	4,873
Loans collectively evaluated for impairment, allowance	21,698	19,626
Loans collectively evaluated for impairment, balance	589,187	576,581
Loans, allowance	21,698	19,626
Loans	593,816	581,454
Commercial Real Estate Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance	536	877
Loans individually evaluated for impairment, balance	37,805	51,471
Loans collectively evaluated for impairment, allowance	32,931	32,610
Loans collectively evaluated for impairment, balance	7,097,794	6,672,729
Loans, allowance	33,467	33,487
Loans	7,135,599	6,724,200
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance	221	1,088
Loans individually evaluated for impairment, balance	12,687	13,602
Loans collectively evaluated for impairment, allowance	11,948	13,194
Loans collectively evaluated for impairment, balance	4,313,304	3,930,218
Loans, allowance	12,169	14,282
Loans	4,325,991	3,943,820
Consumer Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance	0	0
Loans individually evaluated for impairment, balance	0	0
Loans collectively evaluated for impairment, allowance	25	18
Loans collectively evaluated for impairment, balance	5,087	4,349
Loans, allowance	25	18
Loans	$ 5,087	$ 4,349

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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
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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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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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