Commitments and Contingencies (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			78 Months Ended	3 Months Ended	1 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Litigation	Mar. 31, 2013 Government Contract Billing Matter	Sep. 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			$ 34,000
Total revenue billed and recorded since renewal of contract in October 2006	747,031	746,498		56,000
Notices of assessment from the state of Massachusetts related to a corporate excise audit of the 2004 through 2006 tax years					$ 8,191
Number of customer lawsuits						3