Derivative Instruments Derivative Instruments (Fair Value Hedge Attributable to Foreign Currency) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Interest Rate Contract
Derivative Instruments, Gain (Loss) [Line Items]
Fair Value Hedge Liabilities	$ (998)		$ (1,111)
Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease)	(14)		(11)
Hedged Liability, Discontinued Fair Value Hedge, Cumulative Increase (Decrease)	10		0
Interest Rate Contract \| Interest Expense [Member]
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	20	$ (2)
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	20	(2)
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	(25)	1
Interest Rate Contract \| Investment Income (Expense)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0	0
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0	0
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	0	0
Interest Rate Contract \| Insurance Claims [Member]
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0	0
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0	0
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	0	0
Foreign Exchange Contract \| Interest Expense [Member]
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0	0
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0	0
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	0	0
Foreign Exchange Contract \| Investment Income (Expense)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0	(1)
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0	(1)
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	0	0
Foreign Exchange Contract \| Insurance Claims [Member]
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0	0
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0	0
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	0	0
Financial Futures \| Interest Expense [Member]
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0	0
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0	0
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	0	0
Financial Futures \| Investment Income (Expense)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0	0
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0	0
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	0	0
Financial Futures \| Insurance Claims [Member]
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	13	0
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	13	0
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	(13)	$ 0
Other Contract
Derivative Instruments, Gain (Loss) [Line Items]
Fair Value Hedge Liabilities	(580)		(508)
Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease)	(6)		(7)
Hedged Liability, Discontinued Fair Value Hedge, Cumulative Increase (Decrease)	$ 8		$ 0

Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Fair value of all derivative liabilities designated as fair value hedging instruments.

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Amount of cumulative increase (decrease) in fair value of hedged liability in fair value hedge, attributable to hedged risk, remaining after discontinued hedge.

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-Topic 815
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Amount of cumulative increase (decrease) in fair value of hedged liability in fair value hedge, attributable to hedged risk.

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Amount of unrealized gain (loss) included in earnings related to the fair value of the hedged item in an interest rate fair value hedge, offset by the gain (loss) on the hedging instrument to the extent that the fair value hedge is determined to be effective.

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