Commitments and Contingencies - Gains (Losses) Related to Interest Rate Derivatives Designated as Hedges of Fair Value (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Gain Loss On Fair Value Hedges Recognized In Earnings [Line Items]
Gains (losses) included in the consolidated statements of income	$ 898	$ 792	$ 744
Fair value hedge | Interest rate swaps | Interest income
Gain Loss On Fair Value Hedges Recognized In Earnings [Line Items]
Gains (losses) included in the consolidated statements of income	133	290	348
Fair value hedge | Interest rate caps and swaps | Derivatives designated as hedging instruments | Interest income
Gain Loss On Fair Value Hedges Recognized In Earnings [Line Items]
Gains (losses) included in the consolidated statements of income	$ (133)	$ (290)	$ (348)