Note 12 - Minimum Regulatory Capital Requirement - Minimum Capital Requirements (Details) - USD ($) $ in Thousands	Dec. 31, 2016		Dec. 31, 2015
Total capital (to risk weighted assets), actual, amount	$ 191,006		$ 184,054
Total capital (to risk weighted assets), actual, ratio	26.575%		25.527%
Total capital (to risk weighted assets), minimum capital requirement, amount	$ 57,499	[1]	$ 57,681
Total capital (to risk weighted assets), minimum capital requirement, ratio	8.625%	[1]	8.00%
Total capital (to risk weighted assets), minimum to be well capitalized, amount
Total capital (to risk weighted assets), minimum to be well capitalized, ratio
Tier 1 capital (to risk weighted assets), actual, amount	$ 182,706		$ 175,757
Tier 1 capital (to risk weighted assets), actual, ratio	25.42%		24.376%
Tier 1 capital (to risk weighted assets), minimum capital requirement, amount	$ 43,124	[1]	$ 43,261
Tier 1 capital (to risk weighted assets), minimum capital requirement, ratio	6.625%	[1]	6.00%
Tier 1 capital (to risk weighted assets), minimum to be well capitalized, amount
Tier 1 capital (to risk weighted assets), minimum to be well capitalized, ratio
Common equity tier 1 capital (to risk weighted assets), actual, amount	$ 182,706		$ 175,757
Common equity tier 1 capital (to risk weighted assets), actual, ratio	25.42%		24.376%
Common equity tier 1 capital (to risk weighted assets), minimum capital requirement, amount	$ 32,343	[1]	$ 32,446
Common equity tier 1 capital (to risk weighted assets), minimum capital requirement, ratio	5.125%	[1]	4.50%
Common equity tier 1 capital (to risk weighted assets), minimum to be well capitalized, amount
Common equity tier 1 capital (to risk weighted assets), minimum to be well capitalized, ratio
Tier 1 capital (to average assets), actual, amount	$ 182,706		$ 175,757
Tier 1 capital (to average assets), actual, ratio	15.121%		15.088%
Tier 1 capital (to average assets), minimum capital requirement, amount	$ 48,333	[1]	$ 46,594
Tier 1 capital (to average assets), minimum capital requirement, ratio	4.00%	[1]	4.00%
Tier 1 capital (to average assets), minimum to be well capitalized, amount
Tier 1 capital (to average assets), minimum to be well capitalized, ratio
National Bank of Blacksburg [Member]
Total capital (to risk weighted assets), actual, amount	$ 188,095		$ 181,926
Total capital (to risk weighted assets), actual, ratio	26.296%		25.30%
Total capital (to risk weighted assets), minimum capital requirement, amount	$ 57,224	[1]	$ 57,526
Total capital (to risk weighted assets), minimum capital requirement, ratio	8.625%	[1]	8.00%
Total capital (to risk weighted assets), minimum to be well capitalized, amount	$ 71,529		$ 71,908
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	$ 179,795		$ 173,629
Tier 1 capital (to risk weighted assets), actual, ratio	25.136%		24.146%
Tier 1 capital (to risk weighted assets), minimum capital requirement, amount	$ 42,918	[1]	$ 43,145
Tier 1 capital (to risk weighted assets), minimum capital requirement, ratio	6.625%	[1]	6.00%
Tier 1 capital (to risk weighted assets), minimum to be well capitalized, amount	$ 57,224		$ 57,526
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	$ 179,795		$ 173,629
Common equity tier 1 capital (to risk weighted assets), actual, ratio	25.136%		24.146%
Common equity tier 1 capital (to risk weighted assets), minimum capital requirement, amount	$ 32,188	[1]	$ 32,358
Common equity tier 1 capital (to risk weighted assets), minimum capital requirement, ratio	5.125%	[1]	4.50%
Common equity tier 1 capital (to risk weighted assets), minimum to be well capitalized, amount	$ 46,494		$ 46,740
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	$ 179,795		$ 173,629
Tier 1 capital (to average assets), actual, ratio	14.964%		14.888%
Tier 1 capital (to average assets), minimum capital requirement, amount	$ 48,060	[1]	$ 46,648
Tier 1 capital (to average assets), minimum capital requirement, ratio	4.00%	[1]	4.00%
Tier 1 capital (to average assets), minimum to be well capitalized, amount	$ 60,075		$ 58,310
Tier 1 capital (to average assets), minimum to be well capitalized, ratio	5.00%		5.00%

[1] Except with regard to the Company's and 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 (0.625%) which is added to the minimum capital requirements for capital adequacy purposes. The capital conservation buffer is being phased in through four equal annual installments of 0.625% from 2016 to 2019, with full implementation in January 2019 (2.5%). The Company's and the Bank's capital conservation buffer must consist 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.