Short-Term Borrowings - Summary of Securities Pledged as Collateral Under Repurchase Agreements (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Offsetting Liabilities [Line Items]
Total securities pledged	$ 15,088	$ 22,199
Gross amount of recognized liabilities for repurchase agreements	15,088	22,199
Amounts related to agreements not included in offsetting disclosures above	0	0
U.S.Treasury Securities [Member]
Offsetting Liabilities [Line Items]
Total securities pledged	655	861
Obligations of U.S. Government Agencies [Member]
Offsetting Liabilities [Line Items]
Total securities pledged	$ 14,433	$ 21,338

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