Federal Funds Purchased and Securities Sold Under Agreements to Repurchase - Schedule of Remaining Contractual Maturity in Repurchase Agreements (Detail) - USD ($)	Sep. 30, 2022	Dec. 31, 2021
Assets Sold under Agreements to Repurchase [Line Items]
Federal funds purchased	$ 20,356,000	$ 0
Repurchase agreements, Remaining contractual maturity of the agreements	35,400,000	29,300,000
Total	55,802,000	29,268,000
Overnight & Continuous [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Federal funds purchased	20,356,000
Total	21,715,000	1,062,000
30-90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total	5,069,000	3,900,000
Greater Than 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total	29,018,000	24,306,000
US Treasury & Agency Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements, Remaining contractual maturity of the agreements	35,446,000	29,268,000
US Treasury & Agency Securities [Member] | Overnight & Continuous [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements, Remaining contractual maturity of the agreements	1,359,000	1,062,000
US Treasury & Agency Securities [Member] | 30-90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements, Remaining contractual maturity of the agreements	5,069,000	3,900,000
US Treasury & Agency Securities [Member] | Greater Than 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements, Remaining contractual maturity of the agreements	$ 29,018,000	$ 24,306,000