Note 11 - Minimum Regulatory Capital Requirement - Minimum Capital Requirements (Details) - National Bank of Blacksburg [Member] - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Total capital (to risk weighted assets), actual, amount		$ 188,946	$ 202,238
Total capital (to risk weighted assets), actual, ratio		23.128%	24.764%
Total capital (to risk weighted assets), minimum capital requirement, amount	[1]	$ 85,781	$ 80,645
Total capital (to risk weighted assets), minimum capital requirement, ratio	[1]	10.50%	9.875%
Total capital (to risk weighted assets), minimum to be well capitalized, amount		$ 81,696	$ 81,666
Total capital (to risk weighted assets), minimum to be well capitalized, ratio		10.00%	10.00%
Tier 1 capital (to risk weighted assets), actual, amount		$ 182,044	$ 194,823
Tier 1 capital (to risk weighted assets), actual, ratio		22.283%	23.856%
Tier 1 capital (to risk weighted assets), minimum capital requirement, amount	[1]	$ 69,442	$ 64,312
Tier 1 capital (to risk weighted assets), minimum capital requirement, ratio	[1]	8.50%	7.875%
Tier 1 capital (to risk weighted assets), minimum to be well capitalized, amount		$ 65,357	$ 65,333
Tier 1 capital (to risk weighted assets), minimum to be well capitalized, ratio		8.00%	8.00%
Common equity tier 1 capital (to risk weighted assets), actual, amount		$ 182,044	$ 194,823
Common equity tier 1 capital (to risk weighted assets), actual, ratio		22.283%	23.856%
Common equity tier 1 capital (to risk weighted assets), minimum capital requirement, amount	[1]	$ 57,187	$ 52,062
Common equity tier 1 capital (to risk weighted assets), minimum capital requirement, ratio	[1]	7.00%	6.375%
Common equity tier 1 capital (to risk weighted assets), minimum to be well capitalized, amount		$ 53,103	$ 53,083
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		$ 182,044	$ 194,823
Tier 1 capital (to average assets), actual, ratio		14.175%	15.788%
Tier 1 capital (to average assets), minimum capital requirement, amount	[1]	$ 51,371	$ 49,359
Tier 1 capital (to average assets), minimum capital requirement, ratio	[1]	4.00%	4.00%
Tier 1 capital (to average assets), minimum to be well capitalized, amount		$ 64,213	$ 61,699
Tier 1 capital (to average assets), minimum to be well capitalized, ratio		5.00%	5.00%

[1] Except with regard to the Bank's Tier 1 capital to average assets ratio, the minimum capital requirement includes the current phased-in portion of the Basel III Capital Rules capital conservation buffer (2.50% for 2019 and 1.875% in 2018) which is added to the minimum capital requirements for capital adequacy purposes. The capital conservation buffer was phased in through four equal annual installments of .0625% from 2016 to 2019, with full implementation in January 2019. The Bank'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.