Investments (Investment Income Net of Related Expenses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	$ 785	$ 667	$ 1,621	$ 1,283
Investment expense	(26)	(22)	(50)	(44)
Investment income, net of related expenses	759	645	1,571	1,239
Available-for-sale Securities [Member]
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	516	474	1,011	954
Equity securities
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	1	1	3	3
Mortgage Loans on Real Estate [Member]
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	73	66	139	133
Policy loans
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	13	14	27	29
Funds withheld at interest
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	95	69	179	122
Short-term Investments [Member]
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	0	2	1	6
Other invested assets
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	$ 87	$ 41	$ 261	$ 36