Schedule VI (SUPPLEMENTARY INFORMATION CONCERNING PROPERTY AND CASUALTY OPERATIONS) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Abstract]
Deferred Policy Acquisition Costs		$ 4,260	$ 4,244	$ 4,161
Net Reserves for Unpaid Losses		56,759	53,164	48,509
Unearned Premiums		19,101	17,652	16,771
Net Premiums Earned		35,035	31,800	30,189
Net Investment Income		3,133	3,074	3,141
Current Year Claim and Claim Adjustment Expense		22,966	22,124	19,575
Prior Year Claim and Claim Adjustment Expense		(986)	(414)	(845)
Net Losses and Loss Expenses Incurred Related to Prior Year	[1]	(986)	(414)	(845)
Amortization of Deferred Policy Acquisition Costs		6,440	6,076	5,831
Net Paid Losses and Loss Expenses		17,884	17,434	18,473
Net Premiums Written		$ 36,474	$ 32,471	$ 31,126

[1] Relates to prior period loss reserve development only and excludes prior period development related to reinstatement premiums, expense adjustments and earned premiums totaling $60 million, $19 million, and $53 million for 2021, 2020, and 2019, respectively.