Investments Investments - Equity Investments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Equity Securities Excluded From Fair Value Table	$ 8		$ 8
Equity Securities, FV-NI, Realized Gain (Loss)	(3)	$ 0
Debt Securities, Available-for-sale, Allowance for Credit Loss	1	$ 0	0
Real Estate [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	40		33
Hedge Funds, Multi-strategy [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	196		216
Interest Rate Contract [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	88		78
Illiquid Investments [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	87		88
Insurance Linked [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	1		2
Equity [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	91		98
Credit Index Product [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	90		107
Private Equity Funds [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	41		37
Emerging Market Debt [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	17		24
Equity investments in pooled funds [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	652		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
Priced Through Pricing Vendors [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	92		106
Priced Through Pricing Vendors [Member] | Equity [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	75		82
Priced Through Pricing Vendors [Member] | Emerging Market Debt [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	17		$ 24
Commitments [Member] | Partnership Interest [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	$ 70