Investment Securities (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023
Schedule of Investments [Line Items]
Net unsettled investment purchases	$ 952		$ 28
Investment securities, allowance for credit loss	93	$ 92
Pretax loss included in AOCI from derivatives	280		$ 297
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	35,900
Fair value of debt securities of a single issuer that exceeds 10 percent of shareholders equity	34,000
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	$ 31,000