Note 11 - Minimum Regulatory Capital Requirement - Minimum Capital Requirements (Details) - National Bank of Blacksburg [Member] $ in Thousands		Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Total capital (to risk weighted assets), actual, amount		$ 192,907	$ 185,937
Total capital (to risk weighted assets), actual, ratio		0.19495	0.19943
Total capital (to risk weighted assets), minimum capital requirement, amount	[1]	$ 103,898	$ 97,898
Total capital (to risk weighted assets), minimum capital requirement, ratio	[1]	0.10500	0.10500
Total capital (to risk weighted assets), minimum to be well capitalized, amount		$ 98,950	$ 93,236
Total capital (to risk weighted assets), minimum to be well capitalized, ratio		0.10000	0.10000
Tier 1 capital (to risk weighted assets), actual, amount		$ 185,187	$ 177,409
Tier 1 capital (to risk weighted assets), actual, ratio		0.18715	0.19028
Tier 1 capital (to risk weighted assets), minimum capital requirement, amount	[1]	$ 84,108	$ 79,251
Tier 1 capital (to risk weighted assets), minimum capital requirement, ratio	[1]	0.08500	0.08500
Tier 1 capital (to risk weighted assets), minimum to be well capitalized, amount		$ 79,160	$ 74,589
Tier 1 capital (to risk weighted assets), minimum to be well capitalized, ratio		0.08000	0.08000
Common equity tier 1 capital (to risk weighted assets), actual, amount		$ 185,187	$ 177,409
Common equity tier 1 capital (to risk weighted assets), actual, ratio		0.18715	0.19028
Common equity tier 1 capital (to risk weighted assets), minimum capital requirement, amount	[1]	$ 69,265	$ 65,265
Common equity tier 1 capital (to risk weighted assets), minimum capital requirement, ratio	[1]	7.00%	7.00%
Common equity tier 1 capital (to risk weighted assets), minimum to be well capitalized, amount		$ 64,318	$ 60,604
Common equity tier 1 capital (to risk weighted assets), minimum to be well capitalized, ratio		6.50%	6.50%
Tier 1 capital (to average assets), actual, amount		$ 185,187	$ 177,409
Tier 1 capital (to average assets), actual, ratio		0.11165	0.12105
Tier 1 capital (to average assets), minimum capital requirement, amount	[1]	$ 66,348	$ 58,624
Tier 1 capital (to average assets), minimum capital requirement, ratio	[1]	0.04000	0.04000
Tier 1 capital (to average assets), minimum to be well capitalized, amount		$ 82,935	$ 73,281
Tier 1 capital (to average assets), minimum to be well capitalized, ratio		0.05000	0.05000

[1] Except with regard to NBB’s Tier 1 capital to average assets ratio, the minimum capital requirement includes the Basel III Capital Rules’ capital conservation buffer (2.50%) which is added to the minimum capital requirements for capital adequacy purposes. NBB’s capital conservation buffer consists of additional CET1 above regulatory minimum requirement. Failure to maintain the prescribed levels would result in limitations on capital distributions and discretionary bonuses to executives.