Note 4 - Loans and Related Allowance for Loan Loss - Nonperforming Assets (Details) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Non-accrual	$ 3,435,000	$ 3,435,000		$ 4,389,000
Total Nonperforming Loans	703,874,000	703,874,000		681,897,000
Total Nonperforming Assets	$ 908,329,000	$ 908,329,000		$ 846,075,000
Nonperforming Loans to Total Loans	1.05%	1.05%		1.24%
Nonperforming Assets to Total Assets	0.86%	0.86%		1.02%
Nonperforming Financial Instruments [Member]
Non-accrual	$ 3,435,000	$ 3,435,000		$ 4,389,000
Accruing loans past due 90 days or more	623,000	623,000		351,000
Total Nonaccrual Loans and Accruing Loans 90 Days or More Past Due	4,058,000	4,058,000		4,740,000
Nonperforming loans		3,306,000		3,687,000
Total Nonperforming Loans	7,364,000	7,364,000		8,427,000
Total Real Estate Owned	410,000	410,000		174,000
Total Nonperforming Assets	7,774,000	7,774,000		8,601,000
Residential Portfolio Segment [Member] \| Real Estate Sector [Member]
Non-accrual	1,432,000	1,432,000		1,873,000
Total Nonperforming Loans	268,431,000	268,431,000		271,588,000
Residential Portfolio Segment [Member] \| Real Estate Sector [Member] \| Nonperforming Financial Instruments [Member]
Total Real Estate Owned	236,000	236,000
Commercial Portfolio Segment [Member] \| Real Estate Sector [Member]
Non-accrual	288,000	288,000		420,000
Total Nonperforming Loans	203,268,000	203,268,000		201,010,000
Commercial Portfolio Segment [Member] \| Real Estate Sector [Member] \| Nonperforming Financial Instruments [Member]
Total Real Estate Owned	174,000	174,000		174,000
Commercial Portfolio Segment [Member] \| Commercial and Industrial Sector [Member]
Non-accrual	1,629,000	1,629,000		1,829,000
Total Nonperforming Loans	85,749,000	85,749,000		80,812,000
Construction Portfolio Segment [Member] \| Real Estate Sector [Member]
Non-accrual	59,000	59,000		107,000
Total Nonperforming Loans	28,965,000	28,965,000		10,646,000
Consumer Portfolio Segment [Member]
Non-accrual	27,000	27,000		160,000
Total Nonperforming Loans	114,017,000	114,017,000		114,204,000
Other Portfolio Segment [Member]
Non-accrual
Total Nonperforming Loans	3,444,000	3,444,000		3,637,000
Originated Loans [Member]
Non-accrual	2,299,000	2,299,000		2,477,000
Accruing loans past due 90 days or more	548,000	548,000		128,000
Nonperforming loans	61,000	61,000	$ 7,000
Total Nonperforming Loans	567,104,000	567,104,000		525,352,000
Originated Loans [Member] \| Nonperforming Financial Instruments [Member]
Nonperforming loans		1,353,000		1,335,000
Originated Loans [Member] \| Residential Portfolio Segment [Member] \| Real Estate Sector [Member]
Non-accrual	312,000	312,000		308,000
Accruing loans past due 90 days or more				120,000
Nonperforming loans	61,000	61,000
Total Nonperforming Loans	193,214,000	193,214,000		186,077,000
Originated Loans [Member] \| Commercial Portfolio Segment [Member] \| Real Estate Sector [Member]
Non-accrual	288,000	288,000		73,000
Nonperforming loans		1,285,000		1,325,000
Total Nonperforming Loans	150,442,000	150,442,000		139,894,000
Originated Loans [Member] \| Commercial Portfolio Segment [Member] \| Commercial and Industrial Sector [Member]
Non-accrual	1,613,000	1,613,000		1,829,000
Accruing loans past due 90 days or more	496,000	496,000
Nonperforming loans		5,000		6,000
Total Nonperforming Loans	77,217,000	77,217,000		71,091,000
Originated Loans [Member] \| Construction Portfolio Segment [Member] \| Real Estate Sector [Member]
Non-accrual	59,000	59,000		107,000
Total Nonperforming Loans	28,965,000	28,965,000		10,646,000
Originated Loans [Member] \| Consumer Portfolio Segment [Member]
Non-accrual	27,000	27,000		160,000
Accruing loans past due 90 days or more	52,000	52,000		8,000
Total Nonperforming Loans	113,822,000	113,822,000		114,007,000
Originated Loans [Member] \| Other Portfolio Segment [Member]
Non-accrual
Nonperforming loans		2,000	7,000	4,000
Total Nonperforming Loans	3,444,000	3,444,000		3,637,000
Acquired Loans [Member]
Non-accrual	1,136,000	1,136,000		1,912,000
Accruing loans past due 90 days or more	75,000	75,000		223,000
Nonperforming loans		1,953,000	584,000	2,352,000
Total Nonperforming Loans	136,770,000	136,770,000		156,545,000
Acquired Loans [Member] \| Residential Portfolio Segment [Member] \| Real Estate Sector [Member]
Non-accrual	1,120,000	1,120,000		1,565,000
Accruing loans past due 90 days or more	75,000	75,000		223,000
Nonperforming loans		1,268	45,000	1,299
Total Nonperforming Loans	75,217,000	75,217,000		85,511,000
Acquired Loans [Member] \| Commercial Portfolio Segment [Member] \| Real Estate Sector [Member]
Non-accrual				347,000
Nonperforming loans		438,000	$ 539,000	660,000
Total Nonperforming Loans	52,826,000	52,826,000		61,116,000
Acquired Loans [Member] \| Commercial Portfolio Segment [Member] \| Commercial and Industrial Sector [Member]
Non-accrual	16,000	16,000
Nonperforming loans		247		393
Total Nonperforming Loans	8,532,000	8,532,000		9,721,000
Acquired Loans [Member] \| Construction Portfolio Segment [Member] \| Real Estate Sector [Member]
Total Nonperforming Loans
Acquired Loans [Member] \| Consumer Portfolio Segment [Member]
Non-accrual
Total Nonperforming Loans	195,000	195,000		197,000
Acquired Loans [Member] \| Other Portfolio Segment [Member]
Total Nonperforming Loans

Aggregate amount of nonaccrual loans and loans 90 days past due and still accruing.

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Reflects the percentage derived from dividing nonperforming assets by total assets.

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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

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

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Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

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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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Reflects the percentage derived from dividing impaired loans on which interest has ceased to be accrued by total loans.

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Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

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