Short-Term and Other Borrowings - Summary of Securities Pledged as Collateral Under Repurchase Agreements (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Offsetting Liabilities [Line Items]
Total securities pledged	$ 25,813	$ 18,674
Gross amount of recognized liabilities for repurchase agreements	25,813	18,674
Amounts related to agreements not included in offsetting disclosures above	0	0
U.S.Treasury Securities [Member]
Offsetting Liabilities [Line Items]
Total securities pledged	910	810
Obligations of U.S. Government Agencies [Member]
Offsetting Liabilities [Line Items]
Total securities pledged	$ 24,903	$ 17,864

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