Commitments and Contingencies Outstanding Commitments to Extend Credit and Letters of Credit (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Valuation allowances and reserves, balance	$ 4,700	$ 5,300
Commitments to Extend Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Valuation allowances and reserves, balance	9,003,425	8,651,055
Standby Letters of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Valuation allowances and reserves, balance	314,921	298,750
Commercial Letters of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Valuation allowances and reserves, balance	$ 56,862	$ 56,229