Note 1 - Organization and Summary of Significant Accounting Policies (Details Textual) $ in Thousands			3 Months Ended		9 Months Ended
	Jul. 01, 2018 USD ($) shares	Jul. 01, 2016	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)
Fees, Credit and Debit Cards			$ 106	$ 105	$ 295	$ 293
Insurance Services Revenue, Total			14	9	45	26
Mortgage Banking [Member]
Revenue from Contract with Customer, Including Assessed Tax			$ 275	$ 185	$ 861	$ 566
Grayson Bankshares, Inc [Member]
Business Acquisition, Equity Interest Issued or Issuable, Exchange Ratio		1.76
Grayson Bankshares, Inc [Member] | Parkway Acquisition Corp. [Member]
Ownership Percentage in Newly Issued Shares		60.00%
Cardinal Bankshares Corporation [Member]
Business Acquisition, Equity Interest Issued or Issuable, Exchange Ratio		1.30
Cardinal Bankshares Corporation [Member] | Core Deposits [Member]
Finite-Lived Intangible Asset, Useful Life (Year)					20 years
Cardinal Bankshares Corporation [Member] | Parkway Acquisition Corp. [Member]
Ownership Percentage in Newly Issued Shares		40.00%
Great State Bank [Member]
Business Acquisition, Equity Interest Issued or Issuable, Exchange Ratio	1.21
Stock Issued During Period, Shares, Acquisitions (in shares) | shares	1,191,899
Stock Issued During Period, Value, Acquisitions	$ 15,500
Great State Bank [Member] | Core Deposits [Member]
Finite-Lived Intangible Asset, Useful Life (Year)					7 years