Investment Information - Maturity profile of available for sale securities) (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Estimated Fair Value
Due in one year or less	$ 430	$ 480
Due after one year through five years	15,533	12,924
Due after five years through 10 years	6,572	5,249
Due after 10 years	451	334
Single maturity date	22,986	18,987
Estimated Fair Value	31,775	25,616
Amortized Cost
Due in one year or less	445	499
Due after one year through five years	15,457	13,101
Due after five years through 10 years	6,595	5,450
Due after 10 years	470	374
Single maturity date	22,967	19,424
Cost or Amortized Cost	31,803	26,195
Fixed maturities
Estimated Fair Value
Estimated Fair Value	28,434	23,553
Amortized Cost
Cost or Amortized Cost	28,466	24,131
Residential mortgage backed securities
Estimated Fair Value
Securities without single maturity date	1,313	1,103
Estimated Fair Value	1,313	1,103
Amortized Cost
Securities without single maturity date	1,349	1,162
Cost or Amortized Cost	1,349	1,162
Commercial mortgage backed securities
Estimated Fair Value
Securities without single maturity date	1,146	1,213
Estimated Fair Value	1,146	1,213
Amortized Cost
Securities without single maturity date	1,156	1,246
Cost or Amortized Cost	1,156	1,246
Asset backed securities
Estimated Fair Value
Securities without single maturity date	2,989	2,250
Estimated Fair Value	2,989	2,250
Amortized Cost
Securities without single maturity date	2,994	2,299
Cost or Amortized Cost	$ 2,994	$ 2,299