Investment Securities (Narrative) (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Schedule of Investments [Line Items]
Net unsettled investment purchases	$ 200		$ 400
Investment securities, allowance for credit loss	148	$ 149
Pretax loss included in AOCI from derivatives	(301)		$ (141)
Federal National Mortgage Association Certificates and Obligations (FNMA)
Schedule of Investments [Line Items]
Debt securities amortized cost amount of debt securities exceeds 10 percent of shareholders equity	38,500
Fair value of debt securities of a single issuer that exceeds 10 percent of shareholders equity	35,300
Federal Home Loan Mortgage Corporation (FHLMC) Insured Loans
Schedule of Investments [Line Items]
Debt securities amortized cost amount of debt securities exceeds 10 percent of shareholders equity	32,400
Fair value of debt securities of a single issuer that exceeds 10 percent of shareholders equity	$ 30,000