Insurance - Recoverables from reinsurance, progression of allowance for expected credit losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 8	$ 8	$ 6
Provision for expected credit losses	2	0	2
Write-offs charged against the allowance	0	0	0
Ending balance	10	$ 8	$ 8
Crop Risk Services
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Increase in allowance from acquisition of CRS	$ 0