Fair Value Measurements - Assets Measured at Fair Value on Nonrecurring Basis (Detail) - Level 3 [Member] - Nonrecurring [Member] - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Equity Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	$ 9,755	$ 10,121
Repossessed Assets [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	186	465
Collateral Dependent Loans
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	38,625	45,687
Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	$ 3,924	$ 3,024