Consolidated Statement of Cash Flows (Changes in Other Components of Working Capital) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Statement of Cash Flows [Abstract]
Accounts receivable	$ (57,609)	$ (269,900)	$ 4,734
Costs and estimated earnings in excess of billings	(100,932)	73,349	(178,774)
Other current assets	(19,718)	39,480	(38,616)
Accounts payable	(32,225)	56,552	139,290
Billings in excess of costs and estimated earnings	125,757	42,926	(30,985)
Accrued expenses	24,513	(32,937)	(24,426)
Changes in other components of working capital	(60,214)	(90,530)	(128,777)
Interest	50,443	47,403	45,055
Income taxes	$ 39,776	$ 26,908	$ 35,299

The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4297-108586

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

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Amount of cash paid, after deduction of cash paid for capitalized interest, for interest. Includes, but is not limited to, payment to settle zero-coupon bond for accreted interest of debt discount and debt instrument with insignificant coupon interest rate in relation to effective interest rate of borrowing attributable to accreted interest of debt discount.

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