Investments (Major Categories Of Net Investment Income) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Investment Income [Line Items]
Investment income (loss)	$ 915	$ 1,034	$ 1,011
Investment expense	(38)	(29)	(41)
Net investment income	877	1,005	970
Fixed Maturity Securities [Member]
Investment Income [Line Items]
Investment income (loss)	725	721	681
Equity Securities [Member]
Investment Income [Line Items]
Investment income (loss)	71	100	86
Cash Equivalents [Member]
Investment Income [Line Items]
Investment income (loss)	28	64	51
Other Investments [Member]
Investment Income [Line Items]
Investment income (loss)	$ 91	$ 149	$ 193

Amount of expenses related to the generation of investment income.

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Amount after accretion (amortization) of discount (premium), and investment expense, of interest income and dividend income on nonoperating securities.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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