Note 7 - Regulatory Capital - Summary of Company's and Wilson Banks Actual Capital Amounts and Ratios (Details) $ in Thousands	Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Total capital to risk weighted assets actual amount	$ 497,360	$ 455,813
Total capital to risk weighted assets actual ratio	0.135	0.139
Total capital to risk weighted assets regulatory minimum capital requirement amount	$ 294,682	$ 261,404
Total capital to risk weighted assets regulatory minimum capital requirement ratio (	0.080	0.080
Well capitalized amount	$ 368,352	$ 326,755
Total capital to risk weighted assets regulatory minimum capital requirement well capitalized ratio	0.100	0.100
Tier 1 capital to risk weighted assets actual amount	$ 452,928	$ 415,226
Tier 1 capital to risk weighted assets actual ratio	0.123	0.127
Tier 1 capital to risk weighted assets regulatory minimum capital requirement amount	$ 221,011	$ 196,052
Tier 1 capital to risk weighted assets regulatory minimum capital requirement ratio	0.060	0.060
Tier 1 capital to risk well capitalized amount	$ 294,681	$ 261,403
Tier 1 capital to risk weighted assets regulatory well capitalized ratio	0.080	0.080
Common equity Tier 1 capital to risk weighted assets actual amount	$ 452,928	$ 415,226
Common equity Tier 1 capital to risk weighted assets actual ratio	0.123	0.127
Common equity Tier 1 capital to risk weighted assets regulatory minimum capital requirement amount	$ 165,758	$ 147,039
Common equity Tier 1 capital to risk weighted assets regulatory minimum capital requirement ratio	0.045	0.045
Tier 1 capital to average assets actual amount	$ 452,928	$ 415,226
Tier 1 capital to average assets actual ratio	0.110	0.108
Tier 1 capital to average assets regulatory minimum capital requirement amount	$ 165,284	$ 154,280
Tier 1 capital to average assets regulatory minimum capital requirement ratio (as a percent)	0.040	0.040
Wilson Bank [Member]
Total capital to risk weighted assets actual amount	$ 494,996	$ 452,130
Total capital to risk weighted assets actual ratio	0.134	0.138
Total capital to risk weighted assets regulatory minimum capital requirement amount	$ 294,680	$ 261,317
Total capital to risk weighted assets regulatory minimum capital requirement ratio (	0.080	0.080
Well capitalized amount	$ 368,350	$ 326,646
Total capital to risk weighted assets regulatory minimum capital requirement well capitalized ratio	0.100	0.100
Tier 1 capital to risk weighted assets actual amount	$ 450,564	$ 411,543
Tier 1 capital to risk weighted assets actual ratio	0.122	0.126
Tier 1 capital to risk weighted assets regulatory minimum capital requirement amount	$ 221,011	$ 195,987
Tier 1 capital to risk weighted assets regulatory minimum capital requirement ratio	0.060	0.060
Tier 1 capital to risk well capitalized amount	$ 294,681	$ 261,316
Tier 1 capital to risk weighted assets regulatory well capitalized ratio	0.080	0.080
Common equity Tier 1 capital to risk weighted assets actual amount	$ 450,564	$ 411,543
Common equity Tier 1 capital to risk weighted assets actual ratio	0.122	0.126
Common equity Tier 1 capital to risk weighted assets regulatory minimum capital requirement amount	$ 165,758	$ 146,990
Common equity Tier 1 capital to risk weighted assets regulatory minimum capital requirement ratio	0.045	0.045
Common equity Tier 1 capital to risk weighted assets regulatory well capitalized	$ 239,429	$ 212,319
Common equity Tier 1 capital to risk weighted assets well capitalized ratio	0.065	0.065
Tier 1 capital to average assets actual amount	$ 450,564	$ 411,543
Tier 1 capital to average assets actual ratio	0.109	0.107
Tier 1 capital to average assets regulatory minimum capital requirement amount	$ 165,229	$ 154,230
Tier 1 capital to average assets regulatory minimum capital requirement ratio (as a percent)	0.040	0.040
Tier 1 capital to average assets well capitalized	$ 206,537	$ 192,787
Tier 1 capital to average assets well capitalized ratio (as a percent)	0.050	0.050