Derivatives and Hedging Activities - Effect of Derivative Financial Instruments that are Not Designated as Hedging Instruments on Income Statement (Detail) - Not Designated as Hedging Instrument - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Derivative Instruments Gain Loss [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	$ (77,000)	$ 0
Interest Rate Products | Other Income
Derivative Instruments Gain Loss [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	$ (77,000)