Insurance - Analysis of changes in the liability for losses and loss adjustment expenses, net of reinsurance (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Analysis of changes in the liability for losses and loss adjustment expenses, net of reinsurance
Less reinsurance recoverables, net of allowance	$ 4,288	$ 3,767
Net liability at beginning of year	8,799	8,207
Provision for losses and LAE occurring in the current period	1,934	1,850
Net decrease in the provision for claims of prior years	(85)	(125)
Total losses and LAE incurred	1,849	1,725
Payments for losses and LAE of:
Current year	(425)	(338)
Prior years	(1,533)	(1,345)
Total payments	(1,958)	(1,683)
Foreign currency translation and other	(1)	0
Net liability at end of period	8,689	8,249
Add back reinsurance recoverables, net of allowance	$ 3,918	$ 3,676