Schedule VI (SUPPLEMENTARY INFORMATION CONCERNING PROPERTY AND CASUALTY OPERATIONS) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Supplemental Information for Property, Casualty Insurance Underwriters [Abstract]
Deferred Policy Acquisition Costs	$ 1,757	$ 1,512	$ 1,435
Net Reserves for Unpaid Losses	26,547	25,875	25,242
Unearned Premiums	6,864	6,334	6,330
Net Premiums Earned	14,764	14,523	12,893
Net Investment Income	2,018	2,107	1,994
Net Losses and Loss Expenses Incurred Related to Current Year	10,132	10,076	8,082
Net Losses and Loss Expenses Incurred Related to Prior Year	(479)	(556)	(503)
Amortization of Deferred Policy Acquisition Costs	2,254	2,291	2,216
Net Paid Losses and Loss Expenses	9,219	8,866	7,413
Net Premiums Written	$ 15,107	$ 14,455	$ 13,075