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Disclosures About Fair Value of Assets and Liabilities - Unobservable Inputs Used in Recurring and Nonrecurring Level 3 Fair Value Measurements Other Than Goodwill (Details) - Significant Unobservable Inputs (Level 3) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Discounted cash flow | State and municipal securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 2,111	$ 2,444
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	0.02	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	0.04
Discounted cash flow | State and municipal securities | Weighted-average coupon | Weighted-average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount rate	0.04	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 | Risk free rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Risk free rate	3 month LIBOR	3 month LIBOR
Discounted cash flow | Corporate obligations and U.S. Government-sponsored mortgage-backed securities | Plus premium for illiquidity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount rate	0.02	0.02
Collateral based measurements | Collateral dependent loans
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 40,698	$ 37,250
Collateral based measurements | Collateral dependent loans | 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 | Collateral dependent loans | 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 | Collateral dependent loans | 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	0.04	0.06
Appraisals | Other real estate owned
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 185	$ 544
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	0.72	0.30
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	0.39	0.26

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