Note 2 - Summary of Significant Accounting Policies (Details Textual)	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Jan. 01, 2019 USD ($)
Number of Major Customers	0
Cash, Uninsured Amount	$ 10,600,000
Debt Securities, Held-to-maturity, Total	0	$ 0
Debt Securities, Trading	0	0
Federal Home Loan Bank Stock	3,517,000	3,027,000
Government Guaranteed Loans Held for Sale	2,200,000	614,000
Guaranteed Loans With Unpaid Balance	116,421,000	122,379,000
Provision For Off Balance Sheet Commitments	250,000	250,000
Real Estate Acquired Through Foreclosure	707,000	1,170,000	$ 1,344,000
Loans Settled With Other Real Estate Acquired Gross	824,000	2,451,000
Valuation Allowance Related to Loans Settled with Other Real Estate Acquired	$ 117,000	$ 1,281,000
Number of Mortgage Loans in Process of Foreclosure	1	1
Mortgage Loans in Process of Foreclosure, Amount	$ 53,000	$ 90,000
Proceeds from Sale of Other Real Estate	698,000	723,000	689,000
Gains (Losses) on Sales of Other Real Estate	$ 275,000	47,000	130,000
Finite-Lived Intangible Asset, Useful Life	10 years
Amortization of Intangible Assets, Total	$ 263,000	27,000	6,000
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	198,000
Finite-Lived Intangible Assets, Amortization Expense, Year Two	161,000
Finite-Lived Intangible Assets, Amortization Expense, Year Three	132,000
Finite-Lived Intangible Assets, Amortization Expense, Year Four	108,000
Finite-Lived Intangible Assets, Amortization Expense, Year Five	89,000
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax, Total	114,000	(8,000)	(158,000)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax, Total	34,000	(2,000)	(65,000)
Share-based Payment Arrangement, Expense, after Tax	$ 208,000	$ 185,000	$ 141,000
Allocated Share Based Compensation Expense Net of Tax Per Diluted Share | $ / shares	$ 0.04	$ 0.04	$ 0.03
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross | shares	132,000	76,000	0
Accounting Standards Update 2018-02 [Member]
Tax Cuts and Jobs Act of 2017 Reclassification From Aoci to Retained Earnings			$ 94,000
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset				$ 565,000
Operating Lease, Liability, Total				$ 565,000
Residential Portfolio Segment [Member]
Real Estate Acquired Through Foreclosure	$ 0	$ 368,000
Minimum [Member]
Guarantee Loans	75.00%
Minimum [Member] | Building [Member]
Property, Plant and Equipment, Useful Life	20 years
Minimum [Member] | Furniture and Fixtures [Member]
Property, Plant and Equipment, Useful Life	2 years
Maximum [Member]
Guarantee Loans	85.00%
Maximum [Member] | Building [Member]
Property, Plant and Equipment, Useful Life	30 years
Maximum [Member] | Furniture and Fixtures [Member]
Property, Plant and Equipment, Useful Life	10 years
Plumas Statutory Trust I [Member] | Accrued Interest Receivable and Other Assets [Member]
Equity Method Investments	$ 349,000
Plumas Statutory Trust II [Member] | Accrued Interest Receivable and Other Assets [Member]
Equity Method Investments	$ 179,000