Summary of Significant Accounting Policies Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) subsidiarytrusts	Dec. 31, 2020 USD ($)	Jan. 01, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Property, Plant and Equipment [Line Items]
Days past due for nonaccrual status	90 days
Increase in ACL	$ 263,534	$ 291,940		$ 166,209	$ 169,410
Change in retained earnings	1,282,383	1,120,781
Change in ACL for certain OBS credit exposure	$ 3,800	5,300
Financing receivable, obtaining certified third-party appraisal for impaired loans, period	12 months
Foreign currency open position	$ 500
Subsidiary trusts owned by parent | subsidiarytrusts	3
Extension term of leases	5 years
Cumulative Effect, Period of Adoption, Adjustment
Property, Plant and Equipment [Line Items]
Increase in ACL				$ 58,348
Building and Building Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	50 years
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	8 years
Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Consumer Loan
Property, Plant and Equipment [Line Items]
Number of days closed end consumer loans are charged off when they become past due	120 days
Number of days open end consumer loans are charged off when they become past due	180 days
Residential mortgage
Property, Plant and Equipment [Line Items]
Change in ACL for certain OBS credit exposure	$ 1,100	$ 1,100
Accounting Standards Update 2016-13 | Cumulative Effect, Period of Adoption, Adjustment
Property, Plant and Equipment [Line Items]
Increase in ACL			$ 58,300
Change in retained earnings			(43,800)
Change in deferred tax assets			12,400
Accounting Standards Update 2016-13 | Residential mortgage | Cumulative Effect, Period of Adoption, Adjustment
Property, Plant and Equipment [Line Items]
Change in ACL for certain OBS credit exposure			$ 2,100
Employee Equity Plan
Property, Plant and Equipment [Line Items]
Award vesting period	3 years
Directors' Plan
Property, Plant and Equipment [Line Items]
Award vesting period	1 year
Minimum
Property, Plant and Equipment [Line Items]
Remaining lease term of operating leases	1 year
Maximum
Property, Plant and Equipment [Line Items]
Remaining lease term of operating leases	20 years