Investments - Available-for-sale Fixed Maturity Securities by Contractual Maturity (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Cost or Amortized Cost
Cost or Amortized Cost	$ 43,113	$ 42,615
Estimated Fair Value
Estimated Fair Value	40,840	40,626
Available-for-sale Fixed Maturities
Cost or Amortized Cost
Due in one year or less	1,238	1,121
Due after one year through five years	11,680	11,563
Due after five years through ten years	13,283	13,359
Due after ten years	16,677	16,371
Cost or Amortized Cost	42,878	42,414
Estimated Fair Value
Due in one year or less	1,207	1,091
Due after one year through five years	11,308	11,180
Due after five years through ten years	12,461	12,573
Due after ten years	15,629	15,581
Estimated Fair Value	$ 40,605	$ 40,425