Revenue Recognition - Summary of Revenue Recognition (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Schedule Of Revenue Recognition [Line Items]
Total net securities brokerage revenue	$ 3,348	$ 2,601	$ 6,049	$ 5,149
Digital banking income	7,325	5,040	12,730	9,745
Net swap fee and valuation income	746	1,776	1,706	3,339
Mortgage banking income	2,364	1,069	3,504	1,762
Net gain on other real estate owned and other assets	111	34	71	188
Total Service Charges on Deposits [Member]
Schedule Of Revenue Recognition [Line Items]
Total trust fees/Total service charges on deposits	10,484	7,111	19,070	13,895
Trust Account fees [Member]
Schedule Of Revenue Recognition [Line Items]
Total trust fees/Total service charges on deposits	7,698	5,305	$ 14,372	11,405
Point of revenue recognition			Over time
WesMark Fees [Member]
Schedule Of Revenue Recognition [Line Items]
Total trust fees/Total service charges on deposits	1,959	1,998	$ 3,983	3,980
Point of revenue recognition			Over time
Total Trust Fees [Member]
Schedule Of Revenue Recognition [Line Items]
Total trust fees/Total service charges on deposits	9,657	7,303	$ 18,355	15,385
Commercial Banking Fees [Member]
Schedule Of Revenue Recognition [Line Items]
Total trust fees/Total service charges on deposits	2,446	1,297	$ 4,383	2,485
Point of revenue recognition			Over time
Personal Service Charges [Member]
Schedule Of Revenue Recognition [Line Items]
Total trust fees/Total service charges on deposits	8,038	5,814	$ 14,687	11,410
Point of revenue recognition			At a point in time and over time
Annuity Commissions [Member]
Schedule Of Revenue Recognition [Line Items]
Total net securities brokerage revenue	2,610	1,978	$ 4,598	3,950
Point of revenue recognition			At a point in time
Equity And Debt Security Trades [Member]
Schedule Of Revenue Recognition [Line Items]
Total net securities brokerage revenue	84	70	$ 208	150
Point of revenue recognition			At a point in time
Managed Money [Member]
Schedule Of Revenue Recognition [Line Items]
Total net securities brokerage revenue	337	272	$ 664	526
Point of revenue recognition			Over time
Trail Commissions [Member]
Schedule Of Revenue Recognition [Line Items]
Total net securities brokerage revenue	317	281	$ 579	523
Point of revenue recognition			Over time
Payment Processing Fees [Member]
Schedule Of Revenue Recognition [Line Items]
Payment processing fees	$ 804	$ 906	$ 1,696	$ 1,734
Point of revenue recognition			At a point in time and over time
Digital Banking Income [Member]
Schedule Of Revenue Recognition [Line Items]
Point of revenue recognition			At a point in time
Net Swap Fee And Valuation (Loss) Income [Member]
Schedule Of Revenue Recognition [Line Items]
Point of revenue recognition			At a point in time
Mortgage [Member]
Schedule Of Revenue Recognition [Line Items]
Point of revenue recognition			At a point in time
Other Real Estate Owned and Other Assets [Member]
Schedule Of Revenue Recognition [Line Items]
Point of revenue recognition			At a point in time and over time