Federal Funds Purchased and Securities Sold Under Agreements to Repurchase - Schedule of Remaining Contractual Maturity in Repurchase Agreements (Detail) - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Assets Sold under Agreements to Repurchase [Line Items]
Federal funds purchased	$ 0	$ 0
Repurchase agreements, Remaining contractual maturity of the agreements	28,218,000	28,218,000
Total	28,218,000	28,218,000
Greater Than 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total	28,218,000	28,218,000
US Treasury & Agency Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements, Remaining contractual maturity of the agreements	28,218,000	28,218,000
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	$ 28,218,000	$ 28,218,000