Commitments and Contingencies Outstanding Commitments to Extend Credit and Letters of Credit (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Valuation allowances and reserves, balance	$ 3,800	$ 5,300
Commercial and industrial
Valuation allowances and reserves, balance	5,072,008	5,245,041
Commerical mortgage and construction
Valuation allowances and reserves, balance	1,914,238	1,787,963
Real estate - home equity
Valuation allowances and reserves, balance	1,744,922	1,618,051
Total commitments to extend credit
Valuation allowances and reserves, balance	8,731,168	8,651,055
Standby letters of credit
Valuation allowances and reserves, balance	298,275	308,168
Commercial letters of credit
Valuation allowances and reserves, balance	54,196	56,229
Letter of Credit
Valuation allowances and reserves, balance	$ 352,471	$ 364,397