Investments - Net appreciation (decline) recognized in net income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Debt and Equity Securities, FV-NI [Line Items]
Total	$ 812	$ 397
Equity securities
Debt and Equity Securities, FV-NI [Line Items]
Total	377	247
Limited partnership interests carried at fair value
Debt and Equity Securities, FV-NI [Line Items]
Total	$ 435	$ 150