Fair Value (Assets and liabilities measured at fair value on a recurring basis) (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Fixed maturity securities:
Fixed maturity securities	$ 43,402	$ 41,111
Equity securities:
Equity securities	769	659
Short-term and other	2,137	1,922
Total assets	46,308	43,692
Other liabilities	0	0
Total liabilities	0	0
Corporate and other bonds
Fixed maturity securities:
Fixed maturity securities	26,250	25,841
States, municipalities and political subdivisions
Fixed maturity securities:
Fixed maturity securities	8,431	6,804
Asset-backed
Fixed maturity securities:
Fixed maturity securities	8,721	8,466
Common Stock
Equity securities:
Equity securities	237	180
Non-redeemable preferred stock
Equity securities:
Equity securities	532	479
Level 1
Fixed maturity securities:
Fixed maturity securities	238	223
Equity securities:
Equity securities	259	198
Short-term and other	2,086	1,852
Total assets	2,583	2,273
Other liabilities	0	0
Total liabilities	0	0
Level 1 | Corporate and other bonds
Fixed maturity securities:
Fixed maturity securities	238	223
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	224	162
Level 1 | Non-redeemable preferred stock
Equity securities:
Equity securities	35	36
Level 2
Fixed maturity securities:
Fixed maturity securities	40,638	38,692
Equity securities:
Equity securities	497	441
Short-term and other	51	70
Total assets	41,186	39,203
Other liabilities	0	0
Total liabilities	0	0
Level 2 | Corporate and other bonds
Fixed maturity securities:
Fixed maturity securities	24,529	24,340
Level 2 | States, municipalities and political subdivisions
Fixed maturity securities:
Fixed maturity securities	8,386	6,762
Level 2 | Asset-backed
Fixed maturity securities:
Fixed maturity securities	7,723	7,590
Level 2 | Common Stock
Equity securities:
Equity securities	0	0
Level 2 | Non-redeemable preferred stock
Equity securities:
Equity securities	497	441
Level 3
Fixed maturity securities:
Fixed maturity securities	2,526	2,196
Equity securities:
Equity securities	13	20
Short-term and other	0	0
Total assets	2,539	2,216
Other liabilities	0	0
Total liabilities	0	0
Level 3 | Corporate and other bonds
Fixed maturity securities:
Fixed maturity securities	1,483	1,278
Level 3 | States, municipalities and political subdivisions
Fixed maturity securities:
Fixed maturity securities	45	42
Level 3 | Asset-backed
Fixed maturity securities:
Fixed maturity securities	998	876
Level 3 | Common Stock
Equity securities:
Equity securities	13	18
Level 3 | Non-redeemable preferred stock
Equity securities:
Equity securities	$ 0	$ 2