Investments - Equity securities reported at fair value (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Debt and Equity Securities, FV-NI [Line Items]
Equity securities	$ 1,029	$ 1,042
Common stocks
Debt and Equity Securities, FV-NI [Line Items]
Equity securities, at cost	547	491
Equity securities	569	586
Equity securities, fair value in excess of cost	22	95
Perpetual preferred stocks
Debt and Equity Securities, FV-NI [Line Items]
Equity securities, at cost	452	403
Equity securities	460	456
Equity securities, fair value in excess of cost	8	53
Equity securities
Debt and Equity Securities, FV-NI [Line Items]
Equity securities, at cost	999	894
Equity securities	1,029	1,042
Equity securities, fair value in excess of cost	$ 30	$ 148