Lease Obligations - Lessee - Lease Assets and Lease Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating lease right-of-use assets	$ 442	$ 427
Operating lease right-of-use assets [Extensible List]	Other assets	Other assets
Finance lease right-of-use assets	$ 143	$ 145
Finance lease, right-of-use assets [Extensible List]	Bank premises and equipment	Bank premises and equipment
Total right-of-use assets	$ 585	$ 572
Operating lease liabilities	$ 533	$ 520
Operating lease liabilities [Extensible List]	Accrued Liabilities [Member]	Accrued Liabilities [Member]
Finance lease liabilities	$ 148	$ 149
Finance lease liabilities [Extensible List]	Long-term debt	Long-term debt
Total lease liabilities	$ 681	$ 669
Operating lease right of use asset, accumulated amortization	213	198
Finance lease right of use asset, accumulated amortization	$ 51	$ 47