Investments - Debt Securities by Contractual Maturity Periods (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Amortized Cost
Due in one year or less, including assets held for sale	$ 666
Due after one year through five years, including assets held for sale	3,732
Due after five years through ten years, including assets held for sale	3,175
Due after ten years, including assets held for sale	2,137
Mortgage and other asset-backed securities, including assets held for sale	387
Total, including assets held for sale	10,097	$ 10,379
Fair Value
Due in one year or less, including assets held for sale	643
Due after one year through five years, including assets held for sale	3,497
Due after five years through ten years, including assets held for sale	2,945
Due after ten years, including assets held for sale	1,913
Mortgage and other asset-backed securities, including assets held for sale	352
Total, including assets held for sale	$ 9,350	$ 9,855