Operating Information by Segment and Geographic Area - External Revenue and Segment Profit (Loss) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
External revenue
Revenues	$ 4,192,747	$ 4,823,770
Reportable segments
Segment Profit (Loss)
Segment Profit (Loss)	46,600	52,300
Energy & Chemicals
External revenue
Revenues	1,476,600	1,943,000
Energy & Chemicals \| Reportable segments
Segment Profit (Loss)
Segment Profit (Loss)	19,400	105,700
Mining, Industrial, Infrastructure & Power
External revenue
Revenues	1,381,200	907,000
Mining, Industrial, Infrastructure & Power \| Reportable segments
Segment Profit (Loss)
Segment Profit (Loss)	400	(120,400)
Government
External revenue
Revenues	784,700	1,330,500
Government \| Reportable segments
Segment Profit (Loss)
Segment Profit (Loss)	16,600	48,200
Diversified Services
External revenue
Revenues	550,200	643,300
Diversified Services \| Reportable segments
Segment Profit (Loss)
Segment Profit (Loss)	10,200	18,800
Diversified Services \| Intercompany
External revenue
Revenues	95,000	129,000
Forecast revisions for estimated cost growth for a fixed-price, gas-fired power plant project \| Mining, Industrial, Infrastructure & Power \| Reportable segments
Segment reporting information
Change in Forecast Estimate, Increase (Decrease) in Project Cost	$ 26,000	$ 125,000
Change In Forecast Estimate Increase Decrease In Project Cost Per Diluted Share	$ 0.14	$ 0.69

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Represents the increase (decrease) in estimated petrochemical project cost based on forecast revisions, in dollars per diluted share.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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