SCHEDULE VI - Supplemental Information Concerning Property-Casualty Insurance Operations (Details) ([ConsolidatedPropertyAndCasualtyInsuranceEntityMember], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
[ConsolidatedPropertyAndCasualtyInsuranceEntityMember]
Supplemental Information Concerning Property-Casualty Insurance Operations [Line Items]
Deferred policy acquisition costs	$ 339,094	$ 369,081	$ 343,766
Liability for unpaid losses and loss expenses	11,273,091	10,666,604	10,811,483
Unearned premiums	1,433,525	1,578,754	1,685,092
Premiums earned	3,855,606	4,032,906	3,532,272
Losses and loss expenses incurred	3,722,309	2,659,991	1,854,959
Amortization of deferred policy acquisition costs	821,477	856,257	772,294
Paid losses and loss expenses	2,990,559	2,579,018	2,043,878
Premiums written	$ 3,700,575	$ 3,962,677	$ 3,357,820