Commitments and Contingencies (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended			144 Months Ended	3 Months Ended		1 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Litigation	Sep. 30, 2013 Government Contract Billing Matter	Jun. 30, 2013 State of Massachusetts Assessment	Jun. 30, 2012 State of Massachusetts Assessment	Nov. 30, 2011 Italy Fire item
Commitments and Contingencies
Loss contingencies, reasonably possible loss exposure in excess of the amount currently accrued					$ 43,000
Total revenue billed and recorded from October 1, 2001 through September 30, 2013	755,639	748,125	2,257,391	2,246,788		70,600
Aggregate amount of assessed tax including tax, interest and penalties							$ 4,120	$ 8,191
Number of customer lawsuits									3