Investments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Other Investments	$ 475	$ 568
Investment [Line Items]
Other Investments	475	568
Trading Securities, Realized Gain (Loss)	18	(26)	$ 1
Debt Securities, Trading, Unrealized Gain (Loss)	25	(48)	23
Gains (losses) on securities held as of reporting date [Member]
Investment [Line Items]
Other investments	7	(22)	$ 22
Carrying Amount [Member]
Investments, Debt and Equity Securities [Abstract]
Other Investments	77	61
Investment [Line Items]
Other Investments	77	61
Hedge Funds, Multi-strategy [Member]
Investments, Debt and Equity Securities [Abstract]
Other Investments	112	186
Investment [Line Items]
Other Investments	112	186
Illiquid Investments [Member]
Investments, Debt and Equity Securities [Abstract]
Other Investments	84	84
Investment [Line Items]
Other Investments	84	84
Interest Rate Contract [Member]
Investments, Debt and Equity Securities [Abstract]
Other Investments	85	80
Investment [Line Items]
Other Investments	85	80
Interest Rate Contract [Member] | Carrying Amount [Member]
Investments, Debt and Equity Securities [Abstract]
Other Investments	39	0
Investment [Line Items]
Other Investments	39	0
Equity [Member]
Investments, Debt and Equity Securities [Abstract]
Other Investments	38	64
Investment [Line Items]
Other Investments	38	64
Equity [Member] | Carrying Amount [Member]
Investments, Debt and Equity Securities [Abstract]
Other Investments	38	53
Investment [Line Items]
Other Investments	38	53
Credit Index Product [Member]
Investments, Debt and Equity Securities [Abstract]
Other Investments	52	63
Investment [Line Items]
Other Investments	52	63
Private Equity Funds, US
Investments, Debt and Equity Securities [Abstract]
Other Investments	70	47
Investment [Line Items]
Other Investments	70	47
Real Estate [Member]
Investments, Debt and Equity Securities [Abstract]
Other Investments	21	22
Investment [Line Items]
Other Investments	21	22
Convertibles and Bonds with Warrants Attached
Investments, Debt and Equity Securities [Abstract]
Other Investments	0	8
Investment [Line Items]
Other Investments	0	8
Convertibles and Bonds with Warrants Attached | Carrying Amount [Member]
Investments, Debt and Equity Securities [Abstract]
Other Investments	0	8
Investment [Line Items]
Other Investments	0	8
Insurance Linked [Member]
Investments, Debt and Equity Securities [Abstract]
Other Investments	1	1
Investment [Line Items]
Other Investments	1	1
Equity investments in pooled funds [Member]
Investments, Debt and Equity Securities [Abstract]
Other Investments	463	556
Investment [Line Items]
Other Investments	$ 463	$ 556