Derivative Instruments Derivative Instruments (Fair Value Hedge Attributable to Foreign Currency) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Interest Rate Contract | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	$ (18)
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	12
Interest Rate Contract | Insurance Claims
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments			$ 0
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net			0
Interest Rate Contract | Investment Income (Expense)
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	0
Foreign Exchange Contract | Investment Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments			(2)	$ (1)
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net			(2)	7
Foreign Exchange Contract | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0		0	0
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	0		0	0
Foreign Exchange Contract | Insurance Claims
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments			0	0
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net			$ 0	$ 0
Foreign Exchange Contract | Investment Income (Expense)
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	2
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	(4)
Future [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	0
Future [Member] | Insurance Claims
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments		$ (13)
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net		$ 7
Future [Member] | Investment Income (Expense)
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	$ 0