BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations McDermott International, Inc. (“MII”), a corporation incorporated under the laws of the Republic of Panama in 1959, is an engineering, procurement, construction and installation (“EPCI”) company focused on designing and executing complex offshore oil and gas projects worldwide. Providing fully integrated EPCI services, we deliver fixed and floating production facilities, pipeline installations and subsea systems from concept to commissioning. Operating in approximately 20 countries across the Americas, Europe, Africa, the Middle East and Asia, our integrated resources include a diversified fleet of marine vessels, fabrication facilities and engineering offices. We support our activities with comprehensive project management and procurement services, while utilizing our fully integrated capabilities in both shallow water and deepwater construction. Our customers include national, major integrated and other oil and gas companies, and we operate in most major offshore oil and gas producing regions throughout the world. We execute our contracts through a variety of methods, principally fixed-price, but also including cost reimbursable, cost-plus, day-rate and unit-rate basis or some combination of those methods. In these notes to our accompanying unaudited Consolidated Financial Statements, unless the context otherwise indicates, “we,” “us” and “our” mean MII and its consolidated subsidiaries.
Basis of Presentation	Basis of Presentation The accompanying Consolidated Financial Statements are unaudited and have been prepared from our books and records in accordance with Rule 10-1 of Regulation S-X for interim financial information. Accordingly, they do not include all of the information and notes required by accounting principles generally accepted in the United States (“U.S. GAAP”) for complete financial statements. In the opinion of our management, all adjustments, consisting only of normal recurring adjustments, considered necessary for a fair presentation have been included. The results of operations for interim periods are not necessarily indicative of results of operations for a full year. These Consolidated Financial Statements should be read in conjunction with our Consolidated Financial Statements and notes thereto included in MII’s Current Report on Form 8-K filed with the SEC on May 11, 2015.
Business Segments	Business Segments In the first quarter of 2015, we completed changes to our organizational structure which resulted in realignment of our reporting segments. Our North Sea and Africa operations were previously aggregated into the Middle East (“MEA”) reporting segment. However, the responsibility for business decisions relating to the North Sea and Africa was moved to our Americas reporting segment in the first quarter of 2015. As a result, the North Sea and Africa businesses are reflected in our Americas reporting segment, now referred to as Americas, Europe and Africa (collectively, “AEA”). All comparable periods presented have been revised to reflect this change. Accordingly, we report financial results under three reporting segments consisting of AEA, MEA and Asia (“ASA”). We also report certain corporate and other non-operating activities under the heading “Corporate and other,” which primarily reflects corporate personnel and activities, incentive compensation programs and other costs that are generally fully allocated to our reporting segments. However, Corporate restructuring costs associated with our corporate reorganization are not allocated to our reporting segments. See Note 13 for summarized financial information on our segments.
Recently Issued and Adopted Accounting Guidance	Recently Issued and Adopted Accounting Guidance In April 2015, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) 2015-03, Simplifying the Presentation of Debt Issuance Costs, which requires debt issuance costs to be presented in the balance sheet as a direct deduction from the carrying value of the associated debt liability, consistent with the presentation of a debt discount. The standard does not affect the recognition and measurement of debt issuance costs. Therefore, the amortization of debt issuance costs will be calculated using the interest method and be reported as interest expense. Retrospective application of this ASU is required for public entities for annual and interim periods beginning on or after December 15, 2015, and early adoption is permitted. We early adopted this ASU. Our accompanying Consolidated Financial Statements classify debt issuance costs related to long-term debt as components of Long-term debt. These costs were previously reported by us as Assets (see Note 7). All comparable periods presented have been revised to reflect this change. In April 2014, the FASB issued ASU 2014-08, Presentation of Financial Statements and Property, Plant, and Equipment—Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, which amends the definition of a discontinued operation by raising the threshold for a disposal to qualify as discontinued operations. ASU 2014-08 also requires entities to provide additional disclosures about discontinued operations as well as disposal transactions that do not meet the discontinued operations criteria. The pronouncement is effective prospectively for all disposals (except disposals classified as held for sale before the adoption date) or components initially classified as held for sale in periods beginning on or after December 15, 2014. The application of this ASU did not have any impact on the accompanying Consolidated Financial Statements.
Accounting Guidance Issued But Not Adopted	Accounting Guidance Issued But Not Adopted as of March 31, 2015 In April 2015, the FASB issued ASU 2015-04, Practical Expedient for the Measurement Date of an Employer’s Defined Benefit Obligation and Plan Assets. This ASU is intended to provide a practical expedient for the measurement date of defined benefit plan assets and obligations. The practical expedient allows employers with fiscal year-end dates that do not fall on a calendar month-end (e.g., companies with a 52/53-week fiscal year) to measure pension and post-retirement benefit plan assets and obligations as of the calendar month-end date closest to the fiscal year-end. The FASB also provided a similar practical expedient for interim remeasurements for significant events. This ASU requires perspective application and is effective for annual reporting periods beginning after December 15, 2015 and interim periods within those fiscal years. Early adoption is permitted. We are currently assessing the impact of this amendment on our future Consolidated Financial Statements and related disclosures. In February 2015, the FASB issued ASU 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis, which amends and changes the consolidation analysis currently required under U.S. GAAP. This ASU modifies the process used to evaluate whether limited partnerships and similar entities are variable interest entities or voting interest entities; affects the analysis performed by reporting entities regarding variable interest entities, particularly those with fee arrangements and related party relationships; and provides a scope exception for certain investment funds. The amendments in this ASU are effective for annual and interim periods beginning after December 15, 2015. Early adoption is permitted. We are currently assessing the impact of these amendments on our future Consolidated Financial Statements and related disclosures. In January 2015, the FASB issued ASU 2015-01, Income Statement-Extraordinary and Unusual Items (Subtopic 225-20), Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items, which eliminates the concept of extraordinary items. Under this new guidance, entities will no longer be required to separately classify, present and disclose extraordinary events and transactions. The amendments in this ASU are effective for annual and interim periods beginning after December 15, 2015. The application of these amendments is not expected to have an impact on our future Consolidated Financial Statements and related disclosures. In August 2014, the FASB issued ASU 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. Currently, there is no guidance in effect under U.S. GAAP regarding management’s responsibility to assess whether there is substantial doubt about an entity’s ability to continue as a going concern. Under ASU 2014-15, we will be required to assess our ability to continue as a going concern each interim and annual reporting period and provide certain disclosures if there is substantial doubt about our ability to continue as a going concern, including management’s plan to alleviate the substantial doubt. ASU 2014-15 is effective for annual periods ending after December 15, 2016 and interim periods thereafter with early adoption permitted. We are currently assessing the impact of the adoption of ASU 2014-15 on our future Consolidated Financial Statements and related disclosures. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers. This ASU will supersede most of the existing revenue recognition requirements in U.S. GAAP and will require entities to recognize revenue at an amount that reflects the consideration to which an entity expects to be entitled in exchange for transferring goods or services to a customer. It also requires significantly expanded disclosures regarding the qualitative and quantitative information of an entity’s nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. ASU 2014-09 will be effective for us for annual and interim reporting periods beginning after December 15, 2016, with early application not permitted. Retrospective and modified retrospective application is allowed. We are currently evaluating the requirements of this ASU and have not yet determined its impact on our future Consolidated Financial Statements and related disclosures.