Investments - Net appreciation (decline) recognized in net income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Debt and Equity Securities, FV-NI [Line Items]
Total	$ 51	$ (505)	$ 114	$ (556)
Equity securities
Debt and Equity Securities, FV-NI [Line Items]
Total	19	(511)	66	(600)
Limited partnership interests carried at fair value
Debt and Equity Securities, FV-NI [Line Items]
Total	$ 32	$ 6	$ 48	$ 44