Other Operating Expenses (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Other Operating Expenses [Abstract]
Amortization of gross deferred policy acquisition costs	$ 41,957	$ 40,712	$ 34,048
Other underwriting expenses	27,242	25,290	23,894
Expense allowances from reinsurers	(15,185)	(11,503)	(10,081)
Total underwriting expenses	54,014	54,499	47,861
Operating expenses of non-insurance companies	23,416	18,829	20,843
Total other operating expenses	$ 77,430	$ 73,328	$ 68,704