Insurance Claim Reserves (Details) - Reserve Detail for Claims and Claim Adjustment Expenses - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
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	$ 56,907
Claims and claim adjustment expense reserves at end of period	57,983
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	56,897	$ 54,510
Reinsurance recoverables on unpaid losses	8,209	8,153
Net reserves at beginning of year	48,688	46,357
Estimated claims and claim adjustment expenses for claims arising in the current year	11,194	10,430
Estimated decrease in claims and claim adjustment expenses for claims arising in prior years	(387)	(459)
Total increases	10,807	9,971
Claims and claim adjustment expense payments for claims arising in current year	3,357	3,113
Claims and claim adjustment expense payments for claims arising in prior years	6,205	5,274
Total payments	9,562	8,387
Unrealized foreign exchange (gain) loss	(164)	53
Net reserves at end of period	49,769	47,994
Reinsurance recoverables on unpaid losses	8,207	7,901
Claims and claim adjustment expense reserves at end of period	57,976	$ 55,895
Amount of increase in gross claims and claim adjustment expense reserves	1,080
Amount of decrease in reinsurance recoverables on unpaid losses	2
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	10
Claims and claim adjustment expense reserves at end of period	$ 7