Fair Value of Assets and Liabilities - Significant Assumptions Used in Valuation of Level 3 Financial Instruments (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Impaired Loans (Collateral Dependent) | Level 3 | Minimum | Third Party Valuations
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect realizable value	0.00%	0.00%
Impaired Loans (Collateral Dependent) | Level 3 | Maximum | Third Party Valuations
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect realizable value	40.00%	40.00%
Impaired Loans (Collateral Dependent) | Level 3 | Weighted Average | Third Party Valuations
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect realizable value	20.00%	20.00%
Foreclosed Assets Held-for-sale | Level 3 | Minimum | Third Party Valuations
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect realizable value	0.00%	0.00%
Foreclosed Assets Held-for-sale | Level 3 | Maximum | Third Party Valuations
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect realizable value	40.00%	40.00%
Foreclosed Assets Held-for-sale | Level 3 | Weighted Average | Third Party Valuations
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect realizable value	35.00%	35.00%
Mortgage Servicing Rights | Level 3 | Minimum | Third Party Valuations
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect realizable value	9.00%	9.50%
Mortgage Servicing Rights | Level 3 | Maximum | Third Party Valuations
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect realizable value	11.00%	12.50%
Mortgage Servicing Rights | Level 3 | Weighted Average | Third Party Valuations
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect realizable value	9.10%	9.70%
Fair Value, Nonrecurring | Impaired Loans (Collateral Dependent)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value	$ 9,713	$ 12,727
Fair Value, Nonrecurring | Foreclosed Assets Held-for-sale
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value	9	935
Fair Value, Nonrecurring | Mortgage Servicing Rights
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value	$ 661	$ 1,444