Commitments and Contingencies (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Long-term Purchase Commitment [Line Items]
Operating Leases, Future Minimum Payments Due, Current Year	$ 6,928,000
Operating Leases, Future Minimum Payments, Due in Two Years	6,913,000
Operating Leases, Future Minimum Payments, Due in Three Years	3,549,000
Operating Leases, Future Minimum Payments, Due in Four Years	192,000
Operating Leases, Future Minimum Payments, Due in Five Years	124,000
Operating Leases, Future Minimum Payments, Due Thereafter	266,000
Operating Leases, Future Minimum Payments Due	17,972,000
Operating Leases, Rent Expense	8,000,000	8,300,000	8,100,000
Site Service Commitments
Long-term Purchase Commitment [Line Items]
Operating Leases, Future Minimum Payments Due, Current Year	1,067,000
Operating Leases, Future Minimum Payments, Due in Two Years	1,067,000
Operating Leases, Future Minimum Payments, Due in Three Years	1,067,000
Operating Leases, Future Minimum Payments, Due in Four Years	1,067,000
Operating Leases, Future Minimum Payments, Due in Five Years	1,032,000
Operating Leases, Future Minimum Payments, Due Thereafter	6,294,000
Operating Leases, Future Minimum Payments Due	$ 11,594,000