Fair Value Measurements - Assets Measured at Fair Value on Nonrecurring Basis (Detail) - Level 3 [Member] - Nonrecurring [Member] - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Equity Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	$ 23,491	$ 21,203
Repossessed Assets [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	128	291
Collateral Dependent Loans
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	11,858	11,347
Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	$ 6,824	$ 32,066