Federal Funds Purchased and Securities Sold Under Agreements to Repurchase - Schedule of Remaining Contractual Maturity in Repurchase Agreements (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements, Remaining contractual maturity of the agreements	$ 27,292	$ 28,218
Total	27,292	28,218
Overnight & Continuous [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total	74
Greater Than 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total	27,218	28,218
US Treasury & Agency Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements, Remaining contractual maturity of the agreements	27,292	28,218
US Treasury & Agency Securities [Member] | Overnight & Continuous [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements, Remaining contractual maturity of the agreements	74
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	$ 27,218	$ 28,218