Operations by Business Segment and Geographic Area - External Revenue and Segment Profit (Details 2) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
External revenue
Revenue	$ 4,370,700	$ 4,384,600	$ 4,810,100	$ 4,548,600	$ 5,455,200	$ 5,440,100	$ 5,251,700	$ 5,384,600	$ 18,114,048	$ 21,531,577	$ 27,351,573
Reportable segments
Segment profit (loss)
Segment profit									1,032,200	1,262,400	1,209,900
Oil and Gas Segment
External revenue
Revenue									10,040,200	11,524,600	11,620,500
Oil and Gas Segment | Reportable segments
Segment profit (loss)
Segment profit									764,500	670,200	445,800
Industrial and Infrastructure Segment
External revenue
Revenue									4,070,600	5,909,800	10,987,000
Industrial and Infrastructure Segment | Reportable segments
Segment profit (loss)
Segment profit									227,400	385,600	468,000
Government Segment
External revenue
Revenue									2,557,400	2,511,900	2,749,100
Government Segment | Reportable segments
Segment profit (loss)
Segment profit									83,100	92,700	161,400
Global Services Segment
External revenue
Revenue									499,100	581,200	605,800
Global Services Segment | Reportable segments
Segment profit (loss)
Segment profit									45,200	82,600	123,000
Power Segment
External revenue
Revenue									946,700	1,004,100	1,389,200
Power Segment | Reportable segments
Segment profit (loss)
Segment profit									$ (88,000)	$ 31,300	$ 11,700