Fair Value Assets and Liabilities measured on nonrecurring basis (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans carried at fair value	$ 1,103	$ 6,924
Loans Receivable, Fair Value Disclosure	6,794,671	7,112,474
Servicing Asset at Fair Value, Amount	13,500	12,200
Other Assets, Fair Value Disclosure	6,783,848	7,072,339
Other Repossessed Assets	3,300	3,600
Nonrecurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	1,103	6,924
Servicing Asset at Fair Value, Amount	13,482	12,179
Other Assets, Fair Value Disclosure	775	735
Other Repossessed Assets	2,750	3,164
Nonrecurring basis | Residential real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	272	175
Nonrecurring basis | Commercial Real Estate Portfolio Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	831	6,749
Nonrecurring basis | Residential real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	775	735
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	0	0
Level 1 | Nonrecurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	0	0
Level 1 | Nonrecurring basis | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Repossessed Assets	0
Level 1 | Nonrecurring basis | Residential real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	9,720	33,211
Level 2 | Nonrecurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset at Fair Value, Amount	13,482	12,179
Other Assets, Fair Value Disclosure	0	0
Level 2 | Nonrecurring basis | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Repossessed Assets	0
Level 2 | Nonrecurring basis | Residential real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans carried at fair value	1,103	6,924
Loans Receivable, Fair Value Disclosure	6,784,951	7,079,263
Other Assets, Fair Value Disclosure	6,783,848	7,072,339
Fair Value, Inputs, Level 3 [Member] | Nonrecurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	1,103	6,924
Other Assets, Fair Value Disclosure	775	735
Other Repossessed Assets	2,750	3,164
Fair Value, Inputs, Level 3 [Member] | Nonrecurring basis | Residential real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	272	175
Fair Value, Inputs, Level 3 [Member] | Nonrecurring basis | Commercial Real Estate Portfolio Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	831	6,749
Fair Value, Inputs, Level 3 [Member] | Nonrecurring basis | Residential real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	$ 775	$ 735