Investments - Net appreciation (decline) recognized in net income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Debt and Equity Securities, FV-NI [Line Items]
Total	$ (505)	$ 269	$ (556)	$ 504
Equity securities
Debt and Equity Securities, FV-NI [Line Items]
Total	(511)	132	(600)	226
Limited partnership interests carried at fair value
Debt and Equity Securities, FV-NI [Line Items]
Total	$ 6	$ 137	$ 44	$ 278