Insurance Claim Reserves (Details) - Reserve Detail for Claims and Claim Adjustment Expenses - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Reconciliation of beginning and ending reserve balances for claims and claim adjustment expenses [Roll Forward]
Claims and claim adjustment expense reserves at beginning of year	$ 58,649
Claims and claim adjustment expense reserves at end of period	60,571
Property-casualty [Member]
Reconciliation of beginning and ending reserve balances for claims and claim adjustment expenses [Roll Forward]
Claims and claim adjustment expense reserves at beginning of year	58,643	$ 56,897
Reinsurance recoverables on unpaid losses	7,790	8,209
Net reserves at beginning of year	50,853	48,688
Estimated claims and claim adjustment expenses for claims arising in the current year	13,260	11,194
Estimated decrease in claims and claim adjustment expenses for claims arising in prior years	(118)	(387)
Total increases	13,142	10,807
Claims and claim adjustment expense payments for claims arising in current year	3,898	3,357
Claims and claim adjustment expense payments for claims arising in prior years	7,466	6,205
Total payments	11,364	9,562
Unrealized foreign exchange (gain) loss	104	(164)
Net reserves at end of period	52,735	49,769
Reinsurance recoverables on unpaid losses	7,829	8,207
Claims and claim adjustment expense reserves at end of period	60,564	$ 57,976
Amount of increase in gross claims and claim adjustment expense reserves	1,920
Amount of increase in reinsurance recoverables on unpaid losses	39
Accident and health [Member]
Reconciliation of beginning and ending reserve balances for claims and claim adjustment expenses [Roll Forward]
Claims and claim adjustment expense reserves at beginning of year	6
Claims and claim adjustment expense reserves at end of period	$ 7