Insurance - Recoverables from reinsurance, progression of allowance for expected credit losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 10	$ 8	$ 8
Provision for expected credit losses	1	2	0
Write-offs charged against the allowance	0	0	0
Ending balance	$ 11	$ 10	$ 8