Fair Value - Assets Measured at Fair Value on Nonrecurring Basis (Detail) - Impaired Loans - Fair Value, Measurements, Nonrecurring - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value on nonrecurring basis	$ 17,309	$ 19,232
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value on nonrecurring basis	$ 17,309	$ 19,232