Revenue From Contracts With Customers - Narrative (Details) $ in Millions	3 Months Ended
Mar. 31, 2018 USD ($) contract	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Remaining performance obligation \| $	$ 885
Remaining performance obligation expected to be recognize the remainder of 2018	61.00%
Minimum
Disaggregation of Revenue [Line Items]
Revenue recognition, contract term	12 months
Maximum
Disaggregation of Revenue [Line Items]
Revenue recognition, contract term	36 months
Transferred over Time \| Product Concentration Risk \| Revenue from Contract with Customer
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	84.00%	100.00%
Transferred at Point in Time \| Product Concentration Risk \| Revenue from Contract with Customer
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	16.00%	0.00%
Heavy Civil Construction
Disaggregation of Revenue [Line Items]
Number of contracts \| contract	150

Revenue From Contract With Customer, Number Of Contracts

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- Definition

Represents the length of time the Company's contracts generally take to complete.

+ References

No definition available.

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Revenue, Remaining Performance Obligation, Percentage

+ References

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

+ References

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