Investment Information - Maturity profile of available for sale securities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Estimated Fair Value
Estimated fair value	$ 29,819	$ 25,616
Amortized Cost
Amortized cost	30,354	26,195
Fixed maturities available for sale, at fair value
Estimated Fair Value
Due in one year or less	438	480
Due after one year through five years	15,364	12,924
Due after five years through 10 years	5,811	5,249
Due after 10 years	385	334
Single maturity date	21,998	18,987
Estimated fair value	27,035	23,553
Amortized Cost
Due in one year or less	451	499
Due after one year through five years	15,590	13,101
Due after five years through 10 years	6,039	5,450
Due after 10 years	401	374
Single maturity date	22,481	19,424
Amortized cost	27,570	24,131
Mortgage backed securities
Estimated Fair Value
Securities without single maturity date	1,079	1,103
Estimated fair value	1,079	1,103
Amortized Cost
Securities without single maturity date	1,104	1,162
Amortized cost	1,104	1,162
Commercial mortgage backed securities
Estimated Fair Value
Securities without single maturity date	1,058	1,213
Estimated fair value	1,058	1,213
Amortized Cost
Securities without single maturity date	1,064	1,246
Amortized cost	1,064	1,246
Asset backed securities
Estimated Fair Value
Securities without single maturity date	2,900	2,250
Estimated fair value	2,900	2,250
Amortized Cost
Securities without single maturity date	2,921	2,299
Amortized cost	$ 2,921	$ 2,299