Investments - Schedule of Net Appreciation (Decline) Recognized in Net Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Debt and Equity Securities, FV-NI [Line Items]
Total	$ 194	$ 125	$ 278	$ 235
Equity securities
Debt and Equity Securities, FV-NI [Line Items]
Total	178	107	291	170
Limited partnership interests carried at fair value
Debt and Equity Securities, FV-NI [Line Items]
Total	$ 16	$ 18	$ (13)	$ 65