SCHEDULE VI SUPPLEMENTAL INFORMATION CONCERNING PROPERTY-CASUALTY INSURANCE OPERATIONS (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
SUPPLEMENTAL INFORMATION CONCERNING PROPERTY-CASUALTY INSURANCE OPERATIONS
Deferred policy acquisition costs	$ 343	$ 327	$ 313
Reserve for unpaid losses and loss expenses	3,499	3,584	3,598
Discount, if any, deducted from reserves	84	127	136
Unearned premiums	2,178	2,082	1,981
Earned premiums	4,149	3,925	3,808
Net investment income	324	325	326
Losses and loss expenses incurred related to: Current year	3,616	3,053	2,732
Losses and loss expenses incurred related to: Prior years	(272)	(244)	(93)
Amortization of deferred policy acquisition costs	668	635	611
Net losses and loss expenses paid	3,392	2,811	2,640
Net premiums written	4,255	4,019	3,861
Discount rate for workers compensation case and incurred but not reported loss reserves for all years presented (as a percent)	2.50%
Consolidated P&C Entities
SUPPLEMENTAL INFORMATION CONCERNING PROPERTY-CASUALTY INSURANCE OPERATIONS
Deferred policy acquisition costs	343	327	313
Reserve for unpaid losses and loss expenses	3,499	3,584	3,598
Discount, if any, deducted from reserves	84	127	136
Unearned premiums	2,178	2,082	1,981
Earned premiums	4,149	3,925	3,808
Net investment income	324	325	326
Losses and loss expenses incurred related to: Current year	3,616	3,053	2,732
Losses and loss expenses incurred related to: Prior years	(272)	(244)	(93)
Amortization of deferred policy acquisition costs	668	635	611
Net losses and loss expenses paid	3,392	2,811	2,640
Net premiums written	4,255	4,019	3,861
Unconsolidated P&C Entities
SUPPLEMENTAL INFORMATION CONCERNING PROPERTY-CASUALTY INSURANCE OPERATIONS
Deferred policy acquisition costs	0	0	0
Reserve for unpaid losses and loss expenses	0	0	0
Discount, if any, deducted from reserves	0	0	0
Unearned premiums	0	0	0
Earned premiums	0	0	0
Net investment income	0	0	0
Losses and loss expenses incurred related to: Current year	0	0	0
Losses and loss expenses incurred related to: Prior years	0	0	0
Amortization of deferred policy acquisition costs	0	0	0
Net losses and loss expenses paid	0	0	0
Net premiums written	0	0	0
Proportionate share of registrant & subsidiaries
SUPPLEMENTAL INFORMATION CONCERNING PROPERTY-CASUALTY INSURANCE OPERATIONS
Deferred policy acquisition costs	0	0	0
Reserve for unpaid losses and loss expenses	0	0	0
Discount, if any, deducted from reserves	0	0	0
Unearned premiums	0	0	0
Earned premiums	0	0	0
Net investment income	0	0	0
Losses and loss expenses incurred related to: Current year	0	0	0
Losses and loss expenses incurred related to: Prior years	0	0	0
Amortization of deferred policy acquisition costs	0	0	0
Net losses and loss expenses paid	0	0	0
Net premiums written	$ 0	$ 0	$ 0