Fair Value (Assets and liabilities measured at fair value on a recurring basis) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Fixed maturity securities:
Fixed maturity securities	$ 44,380	$ 44,631
Equity securities:
Equity securities	1,035	992
Short term and other	1,872	1,789
Total assets	47,287	47,412
Other liabilities	12	19
Total liabilities	12	19
Corporate and other bonds
Fixed maturity securities:
Fixed maturity securities	24,852	25,234
States, municipalities and political subdivisions
Fixed maturity securities:
Fixed maturity securities	11,943	11,592
Asset-backed
Fixed maturity securities:
Fixed maturity securities	7,585	7,805
Common Stock
Equity securities:
Equity securities	233	195
Non-redeemable preferred stock
Equity securities:
Equity securities	802	797
Level 1
Fixed maturity securities:
Fixed maturity securities	140	355
Equity securities:
Equity securities	285	243
Short term and other	1,798	1,761
Total assets	2,223	2,359
Other liabilities	0	0
Total liabilities	0	0
Level 1 | Corporate and other bonds
Fixed maturity securities:
Fixed maturity securities	140	355
Level 1 | States, municipalities and political subdivisions
Fixed maturity securities:
Fixed maturity securities	0	0
Level 1 | Asset-backed
Fixed maturity securities:
Fixed maturity securities	0	0
Level 1 | Common Stock
Equity securities:
Equity securities	220	175
Level 1 | Non-redeemable preferred stock
Equity securities:
Equity securities	65	68
Level 2
Fixed maturity securities:
Fixed maturity securities	42,691	43,152
Equity securities:
Equity securities	721	722
Short term and other	74	28
Total assets	43,486	43,902
Other liabilities	12	19
Total liabilities	12	19
Level 2 | Corporate and other bonds
Fixed maturity securities:
Fixed maturity securities	23,775	24,109
Level 2 | States, municipalities and political subdivisions
Fixed maturity securities:
Fixed maturity securities	11,887	11,546
Level 2 | Asset-backed
Fixed maturity securities:
Fixed maturity securities	7,029	7,497
Level 2 | Common Stock
Equity securities:
Equity securities	0	0
Level 2 | Non-redeemable preferred stock
Equity securities:
Equity securities	721	722
Level 3
Fixed maturity securities:
Fixed maturity securities	1,549	1,124
Equity securities:
Equity securities	29	27
Short term and other	0	0
Total assets	1,578	1,151
Other liabilities	0	0
Total liabilities	0	0
Level 3 | Corporate and other bonds
Fixed maturity securities:
Fixed maturity securities	937	770
Level 3 | States, municipalities and political subdivisions
Fixed maturity securities:
Fixed maturity securities	56	46
Level 3 | Asset-backed
Fixed maturity securities:
Fixed maturity securities	556	308
Level 3 | Common Stock
Equity securities:
Equity securities	13	20
Level 3 | Non-redeemable preferred stock
Equity securities:
Equity securities	$ 16	$ 7