Legal Proceedings	12 Months Ended
Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Legal Proceedings	Legal Proceedings In the ordinary course of business, we and our affiliates are involved in various legal proceedings alleging, among other things, liability issues or breach of contract or tortious conduct in connection with the performance of services and/or materials provided, the various outcomes of which cannot be predicted with certainty. We and our affiliates are also subject to government inquiries in the ordinary course of business seeking information concerning our compliance with government construction contracting requirements and various laws and regulations, the outcomes of which cannot be predicted with certainty. Some of the matters in which we or our joint ventures and affiliates are involved may involve compensatory, punitive, or other claims or sanctions that, if granted, could require us to pay damages or make other expenditures in amounts that are not probable to be incurred or cannot currently be reasonably estimated. In addition, in some circumstances our government contracts could be terminated, we could be suspended, debarred or incur other administrative penalties or sanctions, or payment of our costs could be disallowed. While any of our pending legal proceedings may be subject to early resolution as a result of our ongoing efforts to resolve the proceedings, whether or when any legal proceeding will be resolved is neither predictable nor guaranteed. Accordingly, it is possible that future developments in such proceedings and inquiries could require us to (i) adjust existing accruals, or (ii) record new accruals that we did not originally believe to be probable or that could not be reasonably estimated. Such changes could be material to our financial condition, results of operations and/or cash flows in any particular reporting period. In addition to matters that are considered probable for which the loss can be reasonably estimated, disclosure is also provided when it is reasonably possible and estimable that a loss will be incurred or when it is reasonably possible that the amount of a loss will exceed the amount recorded. Liabilities relating to legal proceedings and government inquiries, to the extent that we have concluded such liabilities are probable and the amounts of such liabilities are reasonably estimable, are recorded in the consolidated balance sheets. The aggregate liabilities recorded as of December 31, 2017 and 2016 related to these matters were approximately $0.9 million and $4.3 million, respectively, and were primarily included in accounts payable and accrued expenses and other current liabilities in our consolidated balance sheets. The aggregate range of possible loss related to (i) matters considered reasonably possible, and (ii) reasonably possible amounts in excess of accrued losses recorded for probable loss contingencies, including those related to liquidated damages, could have a material impact on our consolidated financial statements if they become probable and the reasonably estimable amount is determined.

Legal Proceedings

In the ordinary course of business, we and our affiliates are involved in various legal proceedings alleging, among other things, liability issues or breach of contract or tortious conduct in connection with the performance of services and/or materials provided, the various outcomes of which cannot be predicted with certainty. We and our affiliates are also subject to government inquiries in the ordinary course of business seeking information concerning our compliance with government construction contracting requirements and various laws and regulations, the outcomes of which cannot be predicted with certainty.

Some of the matters in which we or our joint ventures and affiliates are involved may involve compensatory, punitive, or other claims or sanctions that, if granted, could require us to pay damages or make other expenditures in amounts that are not probable to be incurred or cannot currently be reasonably estimated. In addition, in some circumstances our government contracts could be terminated, we could be suspended, debarred or incur other administrative penalties or sanctions, or payment of our costs could be disallowed. While any of our pending legal proceedings may be subject to early resolution as a result of our ongoing efforts to resolve the proceedings, whether or when any legal proceeding will be resolved is neither predictable nor guaranteed.

Accordingly, it is possible that future developments in such proceedings and inquiries could require us to (i) adjust existing accruals, or (ii) record new accruals that we did not originally believe to be probable or that could not be reasonably estimated. Such changes could be material to our financial condition, results of operations and/or cash flows in any particular reporting period. In addition to matters that are considered probable for which the loss can be reasonably estimated, disclosure is also provided when it is reasonably possible and estimable that a loss will be incurred or when it is reasonably possible that the amount of a loss will exceed the amount recorded.

Liabilities relating to legal proceedings and government inquiries, to the extent that we have concluded such liabilities are probable and the amounts of such liabilities are reasonably estimable, are recorded in the consolidated balance sheets. The aggregate liabilities recorded as of December 31, 2017 and 2016 related to these matters were approximately $0.9 million and $4.3 million, respectively, and were primarily included in accounts payable and accrued expenses and other current liabilities in our consolidated balance sheets. The aggregate range of possible loss related to (i) matters considered reasonably possible, and (ii) reasonably possible amounts in excess of accrued losses recorded for probable loss contingencies, including those related to liquidated damages, could have a material impact on our consolidated financial statements if they become probable and the reasonably estimable amount is determined.