Investments Investments - Equity Investments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Equity Securities Excluded From Fair Value Table	$ 12		$ 12		$ 8
Equity Securities, FV-NI, Realized Gain (Loss)	(1)	$ 0
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	$ 0	0	$ 0	0
Real Estate [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	34		34		33
Hedge Funds, Multi-strategy [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	186		186		216
Interest Rate Contract [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	69		69		78
Illiquid Investments [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	81		81		88
Insurance Linked [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	1		1		2
Equity [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	67		67		98
Credit Index Product [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	58		58		107
Private Equity Funds [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	43		43		37
Emerging Market Debt [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	0		0		24
Equity investments in pooled funds [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	547		547		683
Equity Securities Excluded From Fair Value
Schedule of Equity Method Investments [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0		0
Convertibles and Bonds with Warrants Attached
Schedule of Equity Method Investments [Line Items]
Other investments	7		7
Priced Through Pricing Vendors [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	64		64		106
Priced Through Pricing Vendors [Member] | Equity [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	57		57		82
Priced Through Pricing Vendors [Member] | Emerging Market Debt [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	0		0		$ 24
Gains (losses) on securities held as of reporting date [Member]
Schedule of Equity Method Investments [Line Items]
Equity Securities, FV-NI, Realized Gain (Loss)			(27)	$ 2
Commitments [Member] | Partnership Interest [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	$ 60		$ 60