Investments Investments - Equity Investments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Equity Securities Excluded From Fair Value Table	$ 12		$ 12
Equity Securities, FV-NI, Realized Gain (Loss)	2	$ (3)
Debt Securities, Available-for-sale, Allowance for Credit Loss	1	1	0
Net Realized and Unrealized Gain (Loss) on Trading Securities	7	$ (13)
Real Estate [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	22		22
Hedge Funds, Multi-strategy [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	178		186
Interest Rate Contract [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	84		80
Illiquid Investments [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	87		84
Insurance Linked [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	1		1
Equity [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	68		64
Credit Index Product [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	47		63
Private Equity Funds [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	49		47
Equity investments in pooled funds [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	545		556
Equity Securities Excluded From Fair Value
Schedule of Equity Method Investments [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0
Convertibles and Bonds with Warrants Attached
Schedule of Equity Method Investments [Line Items]
Other investments	9
Priced Through Pricing Vendors [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	65		61
Priced Through Pricing Vendors [Member] | Equity [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	57		53
Priced Through Pricing Vendors [Member] | Convertibles and Bonds with Warrants Attached
Schedule of Equity Method Investments [Line Items]
Other investments	9		$ 8
Commitments [Member] | Partnership Interest [Member]
Schedule of Equity Method Investments [Line Items]
Other investments	$ 57