Derivative Instruments (Current Period Cash Flow Hedges in AOCI (loss) before Taxes) (Details) - Cash Flow Hedging [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Amount of Hedged Item	$ (485)	$ (299)	$ (495)	$ (218)
Cash Flow Derivatives Deferred In OCI	(6)	(86)
Interest Rate Swaps
Derivative Instruments, Gain (Loss) [Line Items]
Cash Flow Derivatives Deferred In OCI	(12)	(57)
Currency Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cash Flow Derivatives Deferred In OCI	(18)	(29)
Investment Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cash Flow Derivative Gains Losses Reclassified Into Income From AOCI	18	8
Investment Income [Member] | Interest Rate Swaps
Derivative Instruments, Gain (Loss) [Line Items]
Cash Flow Derivative Gains Losses Reclassified Into Income From AOCI	1	3
Investment Income [Member] | Currency Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cash Flow Derivative Gains Losses Reclassified Into Income From AOCI	17	5
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cash Flow Derivative Gains Losses Reclassified Into Income From AOCI	2	3
Interest Expense [Member] | Interest Rate Swaps
Derivative Instruments, Gain (Loss) [Line Items]
Cash Flow Derivative Gains Losses Reclassified Into Income From AOCI	2	3
Interest Expense [Member] | Currency Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cash Flow Derivative Gains Losses Reclassified Into Income From AOCI	0	0
Other Comprehensive Income (Loss) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cash Flow Derivatives Deferred In OCI	$ (6)	$ (86)