Insurance - Premiums receivable, progression of allowance for expected credit losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Premium Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 8	$ 10	$ 13
Impact of adoption of new accounting policy	8	8	10	$ 3	$ 13
Provision for expected credit losses	0	(2)	1
Write-offs charged against the allowance	0	0	(1)
Businesses disposed	0	0	0
Ending balance	8	8	10
Impact of adoption of new accounting policy	(8)	(8)	(6)	$ (11)	$ (18)
Provision for expected credit losses	0	2	0
Reinsurance, Loss on Uncollectible Accounts in Period, Amount	0	0	0
Reinsurance Recoverable, Allowance for Credit Loss, Businesses Disposed	$ 0	$ 0	$ (1)