Fair Value Measurements - Summary of Impaired Loans Measured at Fair Value on a Non-Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a nonrecurring basis	$ 1,233	$ 689
Carrying Amount [Member] | Real estate other [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a nonrecurring basis	1,000
Carrying Amount [Member] | SBA [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a nonrecurring basis	233	689
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a nonrecurring basis	1,233	689
Level 3 [Member] | Real estate other [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a nonrecurring basis	1,000
Level 3 [Member] | SBA [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a nonrecurring basis	$ 233	$ 689