Derivative Instruments Derivative Instruments (Fair Value Hedge Attributable to Foreign Currency) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Interest Rate Contract | Interest Expense [Member]
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	$ 0	$ 0
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	0	0
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
Interest Rate Contract | Investment Income [Member]
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	(1)	(3)
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	0	2
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	(1)	(3)
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	0	2
Foreign Exchange Contract | Interest Expense [Member]
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	(2)	0
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	1	0
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	(2)	0
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	1	0
Foreign Exchange Contract | Investment Income [Member]
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	0	0
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	0	0
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