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Loans and Allowance for Credit Losses - Schedule of Collateral-Dependent Non-Accrual Loans (Details) - USD ($)	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 9,233,000		$ 226,000
Allowance for Credit Losses	$ 22,874,000	$ 22,113,000	16,677,000
Weighted average ratio of loans value to collateral dependent loans value	56.00%
Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 9,233,000
Allowance for Credit Losses	0
Nonaccrual collateral dependent loans in process of foreclosure	0
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	8,757,000
Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	459,000
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	17,000
Commercial real estate | Commercial real estate, owner-occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	7,147,000		0
Allowance for Credit Losses	2,778,000	3,135,000
Commercial real estate | Commercial real estate, owner-occupied | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	7,147,000
Allowance for Credit Losses	0
Commercial real estate | Commercial real estate, owner-occupied | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	7,147,000
Commercial real estate | Commercial real estate, owner-occupied | Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	0
Commercial real estate | Commercial real estate, owner-occupied | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	0
Commercial real estate | Commercial real estate, investor-owned
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	1,610,000		0
Allowance for Credit Losses	12,682,000	11,624,000
Commercial real estate | Commercial real estate, investor-owned | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	1,610,000
Allowance for Credit Losses	0
Commercial real estate | Commercial real estate, investor-owned | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	1,610,000
Commercial real estate | Commercial real estate, investor-owned | Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	0
Commercial real estate | Commercial real estate, investor-owned | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	0
Residential loans | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	459,000		168,000
Allowance for Credit Losses	738,000	1,038,000
Residential loans | Home equity | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	459,000
Allowance for Credit Losses	0
Residential loans | Home equity | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	0
Residential loans | Home equity | Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	459,000
Residential loans | Home equity | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	0
Consumer loans | Installment and other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	17,000		$ 58,000
Allowance for Credit Losses	291,000	$ 406,000
Consumer loans | Installment and other consumer | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	17,000
Allowance for Credit Losses	0
Consumer loans | Installment and other consumer | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	0
Consumer loans | Installment and other consumer | Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	0
Consumer loans | Installment and other consumer | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 17,000

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