Borrowings - Schedule of Federal Funds Purchased and Retail Repurchase Agreements (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Federal Funds Purchased And Securities Sold Under Agreements To Repurchase [Abstract]
Federal funds purchased	$ 0	$ 0
Retail repurchase agreements	$ 41,047	$ 50,068

Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Name:	us-gaap_SecuritiesSoldUnderAgreementsToRepurchase
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant