Insurance - Analysis of changes in the liability for losses and loss adjustment expenses, net of reinsurance (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 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	962	883
Net decrease in the provision for claims of prior years	(50)	(63)
Total losses and LAE incurred	912	820
Payments for losses and LAE of:
Current year	(94)	(66)
Prior years	(895)	(815)
Total payments	(989)	(881)
Foreign currency translation and other	1	1
Net liability at end of period	8,723	8,147
Add back reinsurance recoverables, net of allowance	$ 4,327	$ 3,614