Investments - Equity securities reported at fair value (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Debt and Equity Securities, FV-NI [Line Items]
Equity securities	$ 996	$ 1,042
Common stocks
Debt and Equity Securities, FV-NI [Line Items]
Equity securities, at cost	549	491
Equity securities	530	586
Equity securities, fair value in excess of cost	(19)	95
Perpetual preferred stocks
Debt and Equity Securities, FV-NI [Line Items]
Equity securities, at cost	462	403
Equity securities	466	456
Equity securities, fair value in excess of cost	4	53
Equity securities
Debt and Equity Securities, FV-NI [Line Items]
Equity securities, at cost	1,011	894
Equity securities	996	1,042
Equity securities, fair value in excess of cost	$ (15)	$ 148