Investments Investments - Equity Investments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Equity Securities Excluded From Fair Value Table	$ 8		$ 8		$ 8
Equity Securities, FV-NI, Realized Gain (Loss)	(14)	$ 1
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	39		39		33
Hedge Funds, Multi-strategy [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	188		188		216
Interest Rate Contract [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	70		70		78
Illiquid Investments [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	86		86		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	75		75		98
Credit Index Product [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	83		83		107
Private Equity Funds [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	42		42		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	590		590		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
Priced Through Pricing Vendors [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	72		72		106
Priced Through Pricing Vendors [Member] | Equity [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	72		72		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)			(25)	$ 1
Commitments [Member] | Partnership Interest [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	$ 65		$ 65