Investments (Contractual maturity) (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Investments [Abstract]
Due in one year or less, cost or amortized cost	$ 1,150	$ 1,603
Due after one year through five years, cost or amortized cost	9,330	10,637
Due after five years through ten years, cost or amortized cost	14,434	13,294
Due after ten years, cost or amortized cost	16,301	14,411
Cost or Amortized Cost	41,215	39,945
Due in one year or less, estimated fair value	1,153	1,624
Due after one year through five years, estimated fair value	9,154	11,229
Due after five years through ten years, estimated fair value	13,549	14,338
Due after ten years, estimated fair value	15,529	17,182
Estimated Fair Value	$ 39,385	$ 44,373