Derivatives and Risk Management Activities - Schedule of Derivative Instruments (Detail) $ in Thousands	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Matched Interest Rate Swap With Borrower [Member]
Derivative [Line Items]
Notional Amount	$ 175,807	$ 71,860
Positions	32	12
Assets	$ 13,967	$ 4,039
Collateral Pledges	15,120	6,400
Matched Interest Rate Swaps With Counterparty [Member]
Derivative [Line Items]
Notional Amount	$ 175,807	$ 71,860
Positions	32	12
Liabilities	$ 13,967	$ 4,039
Collateral Pledges	$ 15,120	$ 6,400

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value of securities pledged as collateral against derivative liabilities.

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Nominal or face amount used to calculate payment on derivative.

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The number of derivative instruments of a particular group held by the entity.

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