Investment Information - Maturity profile of available for sale securities) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Estimated Fair Value
Estimated Fair Value	$ 24,167	$ 21,015
Amortized Cost
Cost or Amortized Cost	25,562	22,615
Fixed maturities
Estimated Fair Value
Due in one year or less	683	511
Due after one year through five years	12,561	11,016
Due after five years through 10 years	4,515	3,984
Due after 10 years	317	403
Single maturity date	18,076	15,914
Estimated Fair Value	22,485	19,683
Amortized Cost
Due in one year or less	708	537
Due after one year through five years	13,123	11,715
Due after five years through 10 years	5,035	4,527
Due after 10 years	392	480
Single maturity date	19,258	17,259
Cost or Amortized Cost	23,882	21,282
Fixed maturities | Residential mortgage backed securities
Estimated Fair Value
Securities without single maturity date	965	795
Estimated Fair Value	965	795
Amortized Cost
Securities without single maturity date	1,060	877
Cost or Amortized Cost	1,060	877
Fixed maturities | Commercial mortgage backed securities
Estimated Fair Value
Securities without single maturity date	1,102	1,047
Estimated Fair Value	1,102	1,047
Amortized Cost
Securities without single maturity date	1,151	1,107
Cost or Amortized Cost	1,151	1,107
Fixed maturities | Asset backed securities
Estimated Fair Value
Securities without single maturity date	2,342	1,927
Estimated Fair Value	2,342	1,927
Amortized Cost
Securities without single maturity date	2,413	2,039
Cost or Amortized Cost	$ 2,413	$ 2,039