Operations by Business Segment and Geographical Area (Details 3) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Operations by Business Segment and Geographical Area
Total assets	$ 8,727,168	$ 8,276,043
Reportable segments | Oil and Gas Segment
Operations by Business Segment and Geographical Area
Total assets	1,871,800	1,704,400
Reportable segments | Industrial and Infrastructure Segment
Operations by Business Segment and Geographical Area
Total assets	965,500	751,700
Reportable segments | Government Segment
Operations by Business Segment and Geographical Area
Total assets	545,800	827,200
Reportable segments | Global Services Segment
Operations by Business Segment and Geographical Area
Total assets	729,700	768,900
Reportable segments | Power Segment
Operations by Business Segment and Geographical Area
Total assets	$ 205,100	$ 120,600