Fair Value - Financial Assets and Liabilities not Measured at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Carrying Amount
Assets:
Other invested assets, primarily mortgage loans	$ 1,055	$ 1,019
Liabilities:
Short-term debt	1,004	4
Long-term debt	8,436	8,936
Estimated Fair Value
Assets:
Other invested assets, primarily mortgage loans	1,047	987
Liabilities:
Short-term debt	1,004	5
Long-term debt	8,373	8,668
Estimated Fair Value | Level 1
Assets:
Other invested assets, primarily mortgage loans
Liabilities:
Short-term debt
Long-term debt
Estimated Fair Value | Level 2
Assets:
Other invested assets, primarily mortgage loans
Liabilities:
Short-term debt	999
Long-term debt	7,405	7,702
Estimated Fair Value | Level 3
Assets:
Other invested assets, primarily mortgage loans	1,047	987
Liabilities:
Short-term debt	5	5
Long-term debt	$ 968	$ 966