Commitments and Contingencies (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Commitments and Contingencies [Abstract]
Operating Leases, Future Minimum Payments, Due Thereafter	$ 3,758,000
Operating Leases, Future Minimum Payments Due, Current	6,908,000
Commitments and Contingencies	6,852,000
Operating Leases, Rent Expense	8,100,000	7,500,000	7,100,000
Operating Leases, Future Minimum Payments, Due in Four Years	6,847,000
Operating Leases, Future Minimum Payments, Due in Five Years	6,821,000
Operating Leases, Future Minimum Payments, Due in Three Years	6,848,000
Operating Leases, Future Minimum Payments Due	$ 38,034,000