Fair Value Measurements - Summary of Quantitative Fair Value Measurements for Level 3 (Detail) - Fair Value, Inputs, Level 3 $ in Thousands	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Impaired loans, net	$ 9,849	$ 4,084
Other real estate owned, net	1,113	$ 1,916
Valuation Technique Enterprise Value
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Impaired loans, net	$ 5,700
Impaired Loans | Discounted Appraised Value | Selling Cost
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Unobservable Input, Impaired loans	7	7
Impaired Loans | Weighted Average | Discounted Appraised Value | Lack of Marketability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Unobservable Input, Impaired loans	23	24
Impaired Loans | Weighted Average | Discounted Cash Flows | Discount Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Unobservable Input, Impaired loans	6	6
Impaired Loans | Weighted Average | Valuation Technique Enterprise Value | EV Multiple
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Unobservable Input, Impaired loans	7.1
Impaired Loans | Minimum | Discounted Appraised Value | Lack of Marketability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Unobservable Input, Impaired loans	13	13
Impaired Loans | Minimum | Discounted Cash Flows | Discount Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Unobservable Input, Impaired loans	6	6
Impaired Loans | Minimum | Valuation Technique Enterprise Value | EV Multiple
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Unobservable Input, Impaired loans	7
Impaired Loans | Maximum [Member] | Discounted Appraised Value | Lack of Marketability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Unobservable Input, Impaired loans	93	100
Impaired Loans | Maximum [Member] | Discounted Cash Flows | Discount Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Unobservable Input, Impaired loans	7	7
Impaired Loans | Maximum [Member] | Valuation Technique Enterprise Value | EV Multiple
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Unobservable Input, Impaired loans	12.9
Other Real Estate Owned | Weighted Average | Discounted Appraised Value | Selling Cost
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Unobservable Input, Other real estate owned	6	8
Other Real Estate Owned | Weighted Average | Discounted Appraised Value | Lack of Marketability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Unobservable Input, Other real estate owned	58	47
Other Real Estate Owned | Minimum | Discounted Appraised Value | Selling Cost
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Unobservable Input, Other real estate owned	0	6
Other Real Estate Owned | Minimum | Discounted Appraised Value | Lack of Marketability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Unobservable Input, Other real estate owned	41	18
Other Real Estate Owned | Maximum [Member] | Discounted Appraised Value | Selling Cost
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Unobservable Input, Other real estate owned	8	10
Other Real Estate Owned | Maximum [Member] | Discounted Appraised Value | Lack of Marketability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Unobservable Input, Other real estate owned	65	100