Business, Basis of Presentation and Significant Accounting Policies (Revenue Recognition) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue [Line Items]
Unapproved change orders, description	The Company may incur costs subject to change orders, whether approved or unapproved by the customer, and/or claims related to certain contracts. Management determines the probability that such costs will be recovered based upon engineering studies and legal opinions, past practices with the customer, specific discussions, correspondence or preliminary negotiations with the customer. The Company treats such costs as a cost of contract performance in the period incurred if it is not probable that the costs will be recovered, and defers costs or recognizes revenue up to the amount of the related cost if it is probable that the contract price will be adjusted and can be reliably estimated. As of December 31, 2017 and 2016, the Company had approximately $146 million and $17 million, respectively, of change orders and/or claims that had been included as contract price adjustments on certain contracts that were in the process of being resolved in the normal course of business, including through negotiation, arbitration and other proceedings. These contract price adjustments, which are included within costs and earnings in excess of billings or billed accounts receivable, as appropriate, represent management’s best estimate of contract revenue that has been earned and that management believes is probable of collection.
Unbilled Revenues [Member]
Revenue [Line Items]
Unapproved change orders, contract revenue recognized (in dollars)	$ 142	$ 4
Accounts Receivable [Member]
Revenue [Line Items]
Unapproved change orders, expected to be billed and collected within one year, amount (in dollars)	$ 146	$ 17
Maximum [Member]
Revenue [Line Items]
Fixed price contracts, percentage-of-completion method, term within which generally completed (in years)	1 year
Change order approval process, term within which expected to be completed (in years)	1 year
Contracts Accounted for under Percentage-of-Completion [Member] | Maximum [Member]
Revenue [Line Items]
Change in accounting estimate, percentage-of-completion projects, financial effect on project profit, percentage	5.00%	5.00%
Revenue [Member] | Master Service and Other Service Agreements [Member] | Concentration Risk from Type of Arrangement [Member]
Revenue [Line Items]
Concentration risk, percentage of total	36.00%	43.00%	48.00%