Derivatives (Estimated Fair Value of Derivatives Assets and Liabilities after Master Netting Agreements and Cash Collateral) (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Offsetting Derivative Assets [Abstract]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ 7,450	$ 4,122
Derivative Asset, Not Offset, Policy Election Deduction	(6,143)	(3,039)
Derivative Asset, Collateral, Obligation to Return Cash, Offset	(606)	(524)
Derivative Asset, Fair Value, Amount Offset Against Collateral	701	559
Derivative Asset, Collateral, Obligation to Return Securities, Offset	(684)	(558)
Derivative Asset, Including Not Subject to Master Netting Arrangement, after Offset and Deduction, Net of Securities Collateral	17	1
Offsetting Derivative Liabilities [Abstract]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	7,265	5,353
Derivative Liability, Not Offset, Policy Election Deduction	(6,143)	(3,039)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	1,122	2,314
Derivative Liability, Collateral, Right to Reclaim Securities, Offset	(1,121)	(2,306)
Derivative Liability, Including Not Subject to Master Netting Arrangement, after Offset and Deduction, Net of Securities Collateral	$ 1	$ 8