Bank Premises and Equipment - Summary of Bank Premises and Equipment (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization		$ (3,210)	$ (3,072)
Total bank premises and equipment	[1]	2,120	2,088
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 2,392	2,302
Equipment | Lower limit
Property, Plant and Equipment [Line Items]
Useful life		2 years
Equipment | Upper Limit
Property, Plant and Equipment [Line Items]
Useful life		20 years
Buildings
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 1,668	1,612
Buildings | Lower limit
Property, Plant and Equipment [Line Items]
Useful life		1 year
Buildings | Upper Limit
Property, Plant and Equipment [Line Items]
Useful life		30 years
Land and and improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 645	636
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 517	467
Leasehold improvements | Lower limit
Property, Plant and Equipment [Line Items]
Useful life		1 year
Leasehold improvements | Upper Limit
Property, Plant and Equipment [Line Items]
Useful life		30 years
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 84	108
Land and improvements held for sale
Property, Plant and Equipment [Line Items]
Property and equipment, gross		18	27
Buildings held for sale
Property, Plant and Equipment [Line Items]
Property and equipment, gross		6	8
Other property
Property, Plant and Equipment [Line Items]
Land improvements		$ 39	$ 46

[1] Includes $24 and $35 of bank premises and equipment held for sale at December 31, 2021 and 2020, respectively. For further information, refer to Note 7.