Fair Values of Financial Instruments - Unobservable Inputs Used in Recurring and Nonrecurring Level 3 Fair Value Measurements Other Than Goodwill (Details) - Significant Unobservable Inputs (Level 3) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Discounted cash flow | State and municipal securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 2,444	$ 2,858
Discounted cash flow | State and municipal securities | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Maturity Call Date	1 month	1 month
US Muni BQ curve	A-	A-
Discounted cash flow | State and municipal securities | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Maturity Call Date	15 years	15 years
US Muni BQ curve	BBB-	BBB-
Discounted cash flow | State and municipal securities | Discount rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount rate	0.015	0.02
Discounted cash flow | State and municipal securities | Discount rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount rate	0.04	0.05
Discounted cash flow | State and municipal securities | Weighted-average coupon | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount rate	0.0388	0.04
Discounted cash flow | Corporate obligations and U.S. Government-sponsored mortgage backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 35	$ 35
Discounted cash flow | Corporate obligations and U.S. Government-sponsored mortgage backed securities | Weighted-average coupon | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount rate	0	0
Discounted cash flow | Corporate obligations and U.S. Government-sponsored mortgage backed securities | Premium for illiquidity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount rate	0.02	0.02
Collateral based measurements | Impaired loans (collateral dependent)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 37,250	$ 5,653
Collateral based measurements | Impaired loans (collateral dependent) | Discount to reflect current market conditions and ultimate collectability | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect current market conditions and ultimate collectability	0	0
Collateral based measurements | Impaired loans (collateral dependent) | Discount to reflect current market conditions and ultimate collectability | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect current market conditions and ultimate collectability	0.10	0.10
Collateral based measurements | Impaired loans (collateral dependent) | Discount to reflect current market conditions and ultimate collectability | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect current market conditions and ultimate collectability	0.06	0.01
Appraisals | Other real estate owned
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 544	$ 194
Appraisals | Other real estate owned | Discount to reflect current market conditions | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned	0	0
Appraisals | Other real estate owned | Discount to reflect current market conditions | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned	0.30	0.37
Appraisals | Other real estate owned | Discount to reflect current market conditions | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned	0.26	0.37