Premises, Equipment and Leases - Components of Premises and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 8,744	$ 8,993
Less: Accumulated depreciation and amortization	(4,534)	(4,706)
Total premises and equipment, net	4,210	4,287
Land
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	336	366
Buildings and improvements
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	3,854	3,742
Furniture and equipment
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	1,816	1,973
Computer software
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	2,006	2,144
In progress
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 732	$ 768