Disclosures about Fair Value of Assets and Liabilities - Other Assets Measured at Fair Value on Nonrecurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Significant Unobservable Inputs (Level 3) | Mortgage servicing rights
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Impaired loans	$ 12,472	$ 14,327
Significant Unobservable Inputs (Level 3) | Collateral dependent loans
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Impaired loans	13,123	6,806
Fair Value, Nonrecurring | Mortgage servicing rights
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Impaired loans	12,472	14,327
Fair Value, Nonrecurring | Collateral dependent loans
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Impaired loans	13,123	6,806
Fair Value, Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage servicing rights
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Impaired loans	0	0
Fair Value, Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Collateral dependent loans
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Impaired loans	0	0
Fair Value, Nonrecurring | Significant Other Observable Inputs (Level 2) | Mortgage servicing rights
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Impaired loans	0	0
Fair Value, Nonrecurring | Significant Other Observable Inputs (Level 2) | Collateral dependent loans
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Impaired loans	0	0
Fair Value, Nonrecurring | Significant Unobservable Inputs (Level 3) | Mortgage servicing rights
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Impaired loans	12,472	14,327
Fair Value, Nonrecurring | Significant Unobservable Inputs (Level 3) | Collateral dependent loans
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Impaired loans	$ 13,123	$ 6,806