Investments - Equity securities reported at fair value (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Debt and Equity Securities, FV-NI [Line Items]
Equity securities	$ 1,010	$ 1,042
Common stocks
Debt and Equity Securities, FV-NI [Line Items]
Equity securities, at cost	556	491
Equity securities	553	586
Equity securities, fair value in excess of cost	(3)	95
Perpetual preferred stocks
Debt and Equity Securities, FV-NI [Line Items]
Equity securities, at cost	436	403
Equity securities	457	456
Equity securities, fair value in excess of cost	21	53
Equity securities
Debt and Equity Securities, FV-NI [Line Items]
Equity securities, at cost	992	894
Equity securities	1,010	1,042
Equity securities, fair value in excess of cost	$ 18	$ 148