Schedule VI - Supplementary Information Concerning Property/Casualty Insurance Operations (Details) (P&C Operations, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
P&C Operations
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Deferred acquisition costs	$ 537,473	$ 536,664	$ 531,282
Reserves for losses and loss expenses	20,481,065	20,484,121	20,613,901
Reserves for unearned premiums	3,846,568	3,755,117	3,555,260
Net earned premiums	6,014,099	5,765,978	5,327,112
Net investment income	671,071	712,905	819,708
Losses and loss expenses incurred related to - current year	4,021,353	4,081,376	4,363,258
Losses and loss expenses incurred related to - prior year	(289,889)	(315,894)	(284,867)
Net paid losses and loss expenses	3,828,139	3,783,242	3,846,202
Amortization of deferred acquisition costs	882,658	872,399	786,093
Net premiums written	$ 5,903,982	$ 5,957,019	$ 5,433,388