Summary of Significant Accounting Policies (Direct Premium Attributable By Segment) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Annual direct premiums written	$ 2,737,472	$ 2,655,720	$ 2,579,683
Private Passenger Automobile [Member]
Segment Reporting Information [Line Items]
Annual direct premiums written	2,165,557	2,140,531	2,105,602
Homeowners [Member]
Segment Reporting Information [Line Items]
Annual direct premiums written	340,013	318,295	285,188
Commercial Automobile [Member]
Segment Reporting Information [Line Items]
Annual direct premiums written	104,689	74,655	75,642
Other Lines [Member]
Segment Reporting Information [Line Items]
Annual direct premiums written	$ 127,213	$ 122,239	$ 113,251