Note 6 - Troubled Debt Restructurings (Details) - Performing TDR Loans - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Performing TDRs accounted for on accrual status:
Performing TDR loans	$ 2,400	$ 4,600
Percentage of total loans, net	0.50%	1.10%
Performing Financial Instruments [Member]
Performing TDRs accounted for on accrual status:
Performing TDR loans	$ 877	$ 1,422	$ 5,207	$ 8,366	$ 25,388
Percentage of total loans, net	0.10%	0.30%	1.10%	1.70%	4.80%
Residential Portfolio Segment [Member] | Performing Financial Instruments [Member]
Performing TDRs accounted for on accrual status:
Performing TDR loans	$ 0	$ 0	$ 287
Residential Portfolio Segment [Member] | Performing Financial Instruments [Member] | Real Estate Loan [Member]
Performing TDRs accounted for on accrual status:
Performing TDR loans	0	0	287	$ 0	$ 0
Commercial Portfolio Segment [Member] | Performing Financial Instruments [Member]
Performing TDRs accounted for on accrual status:
Performing TDR loans	770	1,141	4,662
Commercial Portfolio Segment [Member] | Performing Financial Instruments [Member] | Real Estate Loan [Member]
Performing TDRs accounted for on accrual status:
Performing TDR loans	765	1,132	1,887	5,901	19,602
Commercial Portfolio Segment [Member] | Performing Financial Instruments [Member] | Construction Loans [Member]
Performing TDRs accounted for on accrual status:
Performing TDR loans	0	0	2,762	29	1,401
Commercial Portfolio Segment [Member] | Performing Financial Instruments [Member] | Lots and Raw Land [Member]
Performing TDRs accounted for on accrual status:
Performing TDR loans	0	0	0	1,667	2,887
Commercial Portfolio Segment [Member] | Performing Financial Instruments [Member] | Commercial and Industrial [Member]
Performing TDRs accounted for on accrual status:
Performing TDR loans	5	9	13	16	64
Consumer Portfolio Segment [Member] | Performing Financial Instruments [Member]
Performing TDRs accounted for on accrual status:
Performing TDR loans	107	281	258
Consumer Portfolio Segment [Member] | Performing Financial Instruments [Member] | Real Estate Loan [Member]
Performing TDRs accounted for on accrual status:
Performing TDR loans	0	165	171	60	53
Consumer Portfolio Segment [Member] | Performing Financial Instruments [Member] | Lots and Raw Land [Member]
Performing TDRs accounted for on accrual status:
Performing TDR loans	107	60	69	667	1,178
Consumer Portfolio Segment [Member] | Performing Financial Instruments [Member] | Home Equity Loan [Member]
Performing TDRs accounted for on accrual status:
Performing TDR loans	0	0	0	0	175
Consumer Portfolio Segment [Member] | Performing Financial Instruments [Member] | Other Loans [Member]
Performing TDRs accounted for on accrual status:
Performing TDR loans	$ 0	$ 56	$ 18	$ 26	$ 28