Fair Value Qualitative information about Level 3 fair value measurements (Details) $ in Thousands	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loan Fair Value	$ 7,484	$ 6,924
Other Assets, Fair Value Disclosure	7,079,812	7,072,339
Loans Held-for-sale, Fair Value Disclosure	17,766	31,666
Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loan Fair Value	7,484	6,924
Other Assets, Fair Value Disclosure	7,079,812	7,072,339
Fair Value, Nonrecurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other Assets, Fair Value Disclosure	735	735
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other Assets, Fair Value Disclosure	735	735
Fair Value, Nonrecurring [Member] | Commercial Real Estate Portfolio Segment [Member] | Loans Receivable [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loan Fair Value		6,749
Fair Value, Nonrecurring [Member] | Residential Real Estate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other Assets, Fair Value Disclosure	735	735
Fair Value, Nonrecurring [Member] | Residential Real Estate [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other Assets, Fair Value Disclosure	735	735
Fair Value, Nonrecurring [Member] | Residential Real Estate [Member] | Loans Receivable [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loan Fair Value		175
Fair Value, Nonrecurring [Member] | Residential Real Estate [Member] | Real Estate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other Assets, Fair Value Disclosure	735	735
Estimate of Fair Value Measurement [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loan Fair Value		$ 6,924
Estimate of Fair Value Measurement [Member] | Fair Value, Nonrecurring [Member] | Commercial Real Estate Portfolio Segment [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loan Fair Value	7,151
Estimate of Fair Value Measurement [Member] | Fair Value, Nonrecurring [Member] | Residential Real Estate [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loan Fair Value	$ 333
Measurement Input, Comparability Adjustment [Member] | Commercial Real Estate Portfolio Segment [Member] | Loans Receivable [Member] | Minimum [Member] | Valuation, Market Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loans Receivable, Measurement Input	0.000	0.000
Measurement Input, Comparability Adjustment [Member] | Commercial Real Estate Portfolio Segment [Member] | Loans Receivable [Member] | Maximum [Member] | Valuation, Market Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loans Receivable, Measurement Input	1.390	1.390
Measurement Input, Comparability Adjustment [Member] | Commercial Real Estate Portfolio Segment [Member] | Loans Receivable [Member] | Maximum [Member] | Valuation, Cost Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loans Receivable, Measurement Input		0.100
Measurement Input, Comparability Adjustment [Member] | Commercial Real Estate Portfolio Segment [Member] | Loans Receivable [Member] | Weighted Average [Member] | Valuation, Market Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loans Receivable, Measurement Input	0.122	0.118
Measurement Input, Comparability Adjustment [Member] | Commercial Real Estate Portfolio Segment [Member] | Loans Receivable [Member] | Weighted Average [Member] | Valuation, Cost Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loans Receivable, Measurement Input		0.100
Measurement Input, Comparability Adjustment [Member] | Residential Real Estate [Member] | Loans Receivable [Member] | Minimum [Member] | Valuation, Market Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loans Receivable, Measurement Input	0.020	0.020
Measurement Input, Comparability Adjustment [Member] | Residential Real Estate [Member] | Loans Receivable [Member] | Maximum [Member] | Valuation, Market Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loans Receivable, Measurement Input	0.478	0.478
Measurement Input, Comparability Adjustment [Member] | Residential Real Estate [Member] | Loans Receivable [Member] | Weighted Average [Member] | Valuation, Market Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loans Receivable, Measurement Input	0.221	0.119
Measurement Input, Comparability Adjustment [Member] | Residential Real Estate [Member] | Real Estate [Member] | Minimum [Member] | Valuation, Market Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other Real Estate Owned, Measurement Input	0.012	0.078
Measurement Input, Comparability Adjustment [Member] | Residential Real Estate [Member] | Real Estate [Member] | Maximum [Member] | Valuation, Market Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other Real Estate Owned, Measurement Input	0.541	0.099
Measurement Input, Comparability Adjustment [Member] | Residential Real Estate [Member] | Real Estate [Member] | Weighted Average [Member] | Valuation, Market Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other Real Estate Owned, Measurement Input	0.314	0.089
Measurement Input, Cap Rate [Member] | Commercial Real Estate Portfolio Segment [Member] | Loans Receivable [Member] | Minimum [Member] | Valuation, Income Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loans Receivable, Measurement Input	0.085	0.093
Measurement Input, Cap Rate [Member] | Commercial Real Estate Portfolio Segment [Member] | Loans Receivable [Member] | Maximum [Member] | Valuation, Income Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loans Receivable, Measurement Input		0.200
Measurement Input, Cap Rate [Member] | Commercial Real Estate Portfolio Segment [Member] | Loans Receivable [Member] | Weighted Average [Member] | Valuation, Income Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loans Receivable, Measurement Input	0.085	0.103
Measurement Input, Long-term Revenue Growth Rate | Commercial Real Estate Portfolio Segment [Member] | Loans Receivable [Member] | Minimum [Member] | Valuation, Cost Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loans Receivable, Measurement Input	0.100
Measurement Input, Long-term Revenue Growth Rate | Commercial Real Estate Portfolio Segment [Member] | Loans Receivable [Member] | Weighted Average [Member] | Valuation, Cost Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loans Receivable, Measurement Input	0.100
Measurement Input, Appraised Value | Commercial Real Estate Portfolio Segment [Member] | Loans Receivable [Member] | Minimum [Member] | Valuation, Cost Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loans Receivable, Measurement Input	0.010	0.026
Measurement Input, Appraised Value | Commercial Real Estate Portfolio Segment [Member] | Loans Receivable [Member] | Maximum [Member] | Valuation, Cost Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loans Receivable, Measurement Input	0.043
Measurement Input, Appraised Value | Commercial Real Estate Portfolio Segment [Member] | Loans Receivable [Member] | Weighted Average [Member] | Valuation, Cost Approach [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired Loans Receivable, Measurement Input	0.017	0.026