SCHEDULE VI - SUPPLEMENTARY INFORMATION CONCERNING PROPERTY/CASUALTY (RE)INSURANCE OPERATIONS (Detail) - Schedule Of Supplemental Information For Property Casualty Insurance Underwriters (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Deferred Acquisition Costs	$ 531,282	[1]	$ 498,385	[1]	$ 486,180	[1]
Reserves For Losses and Loss Expenses	20,613,901	[1]	20,531,607	[1]	20,823,524	[1]
Reserves for Unearned Premiums	3,555,310	[1]	3,469,934	[1]	3,646,815	[1]
Net Earned Premiums	5,327,112	[1]	5,031,137	[1]	5,151,739	[1]
Supplementary Information Net Investment Income	745,138	[1]	803,358	[1]	882,748	[1]
Losses and Loss Expenses incurred related to Current Year	4,363,258	[1]	3,584,662	[1]	3,453,577	[1]
Losses and Loss Expenses incurred related to Prior Year	(284,867)	[1]	(372,862)	[1]	(284,740)	[1]
Net Paid Losses and Loss Expenses	3,846,202	[1]	3,470,509	[1]	3,875,935	[1]
Amortization of Deferred Acquisition Costs	786,093	[1]	739,154	[1]	775,869	[1]
Net Premiums Written	$ 5,433,388	[1]	$ 4,999,588	[1]	$ 4,743,712	[1]

[1] The information presented above includes P&C Operations balances only.