Supplemental Financial Statement Information (Schedule of Other Operating Cost and Expense, by Component) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Other Income and Expenses [Abstract]
Amortization of deferred policy acquisition costs	$ 991,070	$ 917,583	$ 785,118
Other underwriting expenses	780,058	675,163	653,011
Service company expenses	88,662	84,986	75,231
Net foreign currency losses	(10,120)	(6,092)	(1,884)
Other costs and expenses	151,014	127,983	115,050
Total	$ 2,000,684	$ 1,799,623	$ 1,626,526