Insurance - Analysis of changes in the liability for losses and loss adjustment expenses, net of reinsurance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Analysis of changes in the liability for losses and loss adjustment expenses, net of reinsurance
Balance at beginning of period	$ 11,074	$ 10,392	$ 10,232
Less reinsurance recoverables, net of allowance	3,767	3,419	3,117	$ 3,024
Net liability at beginning of period	7,655	7,275	7,208
Provision for losses and LAE occurring in the current year	3,914	3,436	3,398
Net increase (decrease) in the provision for claims of prior years:
Total losses and LAE incurred	3,629	3,157	3,271
Payments for losses and LAE of:
Current year	(1,212)	(1,024)	(990)
Prior years	(1,870)	(1,753)	(1,766)
Total payments	(3,082)	(2,777)	(2,756)
Reserves of businesses disposed	0	0	(449)
Foreign currency translation and other	5	0	1
Net liability at end of period	8,207	7,655	7,275
Add back reinsurance recoverables, net of allowance	3,767	3,419	3,117
Gross unpaid losses and LAE included in the balance sheet	11,974	11,074	10,392
Special A&E charges
Net increase (decrease) in the provision for claims of prior years:
Special A&E charges	0	0	47
Neon exited lines
Net increase (decrease) in the provision for claims of prior years:
Prior year claims and claims adjustment expense	0	0	19
Other
Net increase (decrease) in the provision for claims of prior years:
Prior year claims and claims adjustment expense	$ (285)	$ (279)	$ (193)