Significant Accounting Policies (Policies)	9 Months Ended
Significant Accounting Policies (Policies)	Sep. 30, 2015
Significant Accounting Policies [Abstract]
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update (“ASU”) ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes the revenue recognition requirements in ASC 605, Revenue Recognition. This ASU addresses when an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers: (Topic 606): Deferral of the Effective Date, which defers the effective date to annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. The Company is currently evaluating the effect that the adoption of this ASU will have on its financial statements. In June 2014, the FASB issued ASU No. 2014-12, Compensation — Stock Compensation (Topic 718): Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period, clarifying the recognition timing of expense associated with certain performance-based stock awards when the performance target that affects vesting could be achieved after the requisite service period. This ASU is an update to FASB ASC Topic 718 and is effective for fiscal years, and interim periods within those years, beginning after December 15, 2015 with earlier adoption permitted. The adoption of this guidance is not expected to have a material impact on the Company’s financial statements. In February 2015, the FASB issued ASU No. 2015-02, Consolidation (Topic 810). The goal of this ASU is to reduce the potentially distortive impact on reporting entities’ consolidated financial statements resulting from the consolidation of certain legal entities, including joint ventures and variable interest entities. This ASU is effective for fiscal years, and interim periods within those years, beginning after December 15, 2015. The Company is currently evaluating the effect that the adoption of this ASU will have on its financial statements. In April 2015, the FASB issued ASU 2015-03, Interest – Imputation of Interest (Subtopic 835-30). This ASU requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. In August 2015, the FASB also issued ASU 2015-15, Interest—Imputation of Interest (Subtopic 835-30): Presentation and Subsequent Measurement of Debt Issuance Costs Associated With Line-of-Credit Arrangements — Amendments to SEC Paragraphs Pursuant to Staff Announcement at June 18, 2015, EITF Meeting. This update allows an entity to defer and present debt issuance costs related to line-of-credit arrangements as an asset and subsequently amortize the deferred debt issuance costs ratably over the term of the line-of-credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. These ASUs are effective for fiscal years, and interim periods within those years, beginning after December 15, 2015. The adoption of these ASUs is not expected to have a material impact on the Company’s financial statements.
Use of and Changes in Estimates	Use of and Changes in Estimates The Company’s construction business involves making significant estimates and assumptions in the normal course of business relating to its contracts and its joint venture contracts. Management focuses on evaluating the performance of contracts individually. These estimates can vary in the normal course of business as projects progress, when estimated productivity assumptions change based on experience to date and uncertainties are resolved. Change orders and claims, as well as changes in related estimates of costs to complete, are considered revisions in estimates. The Company uses the cumulative catch-up method applicable to construction contract accounting to account for revisions in estimates. The impact on operating margin in a reporting period and future periods from a change in estimate will depend on the stage of contract completion. In the third quarter of 2015, the Company recorded a charge for an adverse legal decision related to a long-standing litigation matter, for which the Company assumed liability as part of an acquisition in 2011. This charge resulted in a decrease of $23.9 million in income from construction operations, $14.0 million in net income and $0.28 in diluted earnings per share (for further information, refer to the Brightwater Matter discussion in Note 7. Contingencies and Commitments and Note 16. Subsequent Event). Additionally, in the third quarter of 2015, the Company recorded favorable adjustments for a Civil segment runway reconstruction project related to the estimated cost to complete and the achievement of certain performance-based milestones that resulted in an increase of $13.7 million in income from construction operations, $7.9 million in net income and $0.16 in diluted earnings per share. Previously, in the second quarter of 2015, the Company recorded a significant adverse change in the estimated cost to complete a Building segment project, which is substantially complete and resulted in a decrease of $14.7 million in income from construction operations, $8.7 million in net income and $0.17 in diluted earnings per share. There were other immaterial changes in estimates for these projects during the nine months ended September 30, 2015; these immaterial changes offset each other. During the three and nine months ended September 30, 2014, the Company's income from construction operations was positively impacted by $15.8 million and $30.6 million, respectively, because of changes in the estimated recoveries on two Civil segment projects and a Building segment project. These changes in estimates were driven by changes in cost recovery assumptions based on legal rulings pertaining to the Civil segment projects that were issued during the second quarter of 2014, as well as agreements reached with a customer regarding the Building segment project in the third quarter of 2014. The Building project change in estimate resulted in a $14.1 million increase in income from construction operations in the third quarter of 2014. With respect to the two Civil segment projects, during the nine months ended September 30, 2014, there was a $25.9 million increase and a $9.4 million decrease in income from construction operations. The above changes in estimates also resulted in increases of $9.5 million and $18.3 million in net income, and $0.19 and $0.37 in diluted earnings per share during the three and nine months ended September 30, 2014, respectively. The above were the only changes in estimates considered individually material to the Company’s results of operations during the periods presented herein.