Investments, Net Investment Income (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) Investment	Dec. 31, 2020 USD ($) Investment	Dec. 31, 2019 USD ($)
Net Investment Income [Line Items]
Investment income, operating	$ 2,334	$ 2,071	$ 2,430
Investment expenses	(75)	(76)	(75)
Net investment income	2,259	1,995	2,355
Trading Securities, Change in Unrealized Holding Gain (Loss), Net Investment Income Recognized	$ 23	$ 88	41
Number of investments in single issuer exceeding 10% | Investment	0	0
Total fixed maturities
Net Investment Income [Line Items]
Investment income, operating	$ 1,707	$ 1,728	1,817
Limited partnership investments
Net Investment Income [Line Items]
Gain (losses) on investments, before investment expenses	375	127	204
Short term investments
Net Investment Income [Line Items]
Investment income, operating	2	10	52
Equity securities
Net Investment Income [Line Items]
Investment income, operating	83	65	85
Income (loss) from trading portfolio
Net Investment Income [Line Items]
Gain (losses) on investments, before investment expenses	106	83	216
Other
Net Investment Income [Line Items]
Investment income, operating	$ 61	$ 58	$ 56