SCHEDULE VI SUPPLEMENTAL INFORMATION CONCERNING PROPERTY-CASUALTY INSURANCE OPERATIONS (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
SUPPLEMENTAL INFORMATION CONCERNING PROPERTY-CASUALTY INSURANCE OPERATIONS
Deferred policy acquisition costs	$ 364	$ 343	$ 327
Reserve for unpaid losses and loss expenses	3,598	3,499	3,584
Discount, if any, deducted from reserves	85	84	127
Unearned premiums	2,365	2,178	2,082
Earned premiums	4,422	4,149	3,925
Net investment income	327	324	325
Losses and loss expenses incurred related to: Current year	3,494	3,616	3,053
Losses and loss expenses incurred related to: Prior years	(115)	(272)	(244)
Amortization of deferred policy acquisition costs	705	668	635
Net losses and loss expenses paid	3,283	3,392	2,811
Net premiums written	4,603	4,255	4,019
Discount rate for workers compensation case and incurred but not reported loss reserves (as a percent)	2.50%	2.50%	2.50%
Consolidated P&C Entities
SUPPLEMENTAL INFORMATION CONCERNING PROPERTY-CASUALTY INSURANCE OPERATIONS
Deferred policy acquisition costs	364	343	327
Reserve for unpaid losses and loss expenses	3,598	3,499	3,584
Discount, if any, deducted from reserves	85	84	127
Unearned premiums	2,365	2,178	2,082
Earned premiums	4,422	4,149	3,925
Net investment income	327	324	325
Losses and loss expenses incurred related to: Current year	3,494	3,616	3,053
Losses and loss expenses incurred related to: Prior years	(115)	(272)	(244)
Amortization of deferred policy acquisition costs	705	668	635
Net losses and loss expenses paid	3,283	3,392	2,811
Net premiums written	4,603	4,255	4,019
Unconsolidated P&C Entities
SUPPLEMENTAL INFORMATION CONCERNING PROPERTY-CASUALTY INSURANCE OPERATIONS
Deferred policy acquisition costs
Reserve for unpaid losses and loss expenses
Discount, if any, deducted from reserves
Unearned premiums
Earned premiums
Net investment income
Losses and loss expenses incurred related to: Current year
Losses and loss expenses incurred related to: Prior years
Amortization of deferred policy acquisition costs
Net losses and loss expenses paid
Net premiums written
Proportionate share of registrant & subsidiaries
SUPPLEMENTAL INFORMATION CONCERNING PROPERTY-CASUALTY INSURANCE OPERATIONS
Deferred policy acquisition costs
Reserve for unpaid losses and loss expenses
Discount, if any, deducted from reserves
Unearned premiums
Earned premiums
Net investment income
Losses and loss expenses incurred related to: Current year
Losses and loss expenses incurred related to: Prior years
Amortization of deferred policy acquisition costs
Net losses and loss expenses paid
Net premiums written