Organization and Significant Accounting Policies	12 Months Ended
Dec. 31, 2015
Accounting Policies [Abstract]
Organization and Significant Accounting Policies	Note 1 - Organization and Significant Accounting Policies Organization and Business Noble Corporation plc, a public limited company incorporated under the laws of England and Wales (“Noble-UK”), is a leading offshore drilling contractor for the oil and gas industry. We perform contract drilling services with our global fleet of mobile offshore drilling units. As of the filing date of this Annual Report on Form 10-K, our fleet of 30 drilling rigs consisted of 14 jackups, eight drillships and eight semisubmersibles, including one high-specification, harsh environment jackup under construction. At December 31, 2015, our fleet was located in the United States, Brazil, Argentina, the North Sea, the Mediterranean, West Africa, the Middle East, Asia and Australia. Noble and its predecessors have been engaged in the contract drilling of oil and gas wells since 1921. On November 20, 2013, pursuant to the Merger Agreement dated as of June 30, 2013 between Noble Corporation, a Swiss corporation (“Noble-Swiss”), and Noble-UK, Noble-Swiss merged with and into Noble-UK, with Noble-UK as the surviving company (the “Transaction”). In the Transaction, all of the outstanding ordinary shares of Noble-Swiss were cancelled, and Noble-UK issued, through an exchange agent, one ordinary share of Noble-UK in exchange for each ordinary share of Noble-Swiss. The Transaction effectively changed the place of incorporation of our publicly traded parent holding company from Switzerland to the United Kingdom. Noble Corporation, a Cayman Islands company (“Noble-Cayman”), is an indirect, wholly-owned subsidiary of Noble-UK, our publicly-traded parent company. Noble-UK’s principal asset is all of the shares of Noble-Cayman. Noble-Cayman has no public equity outstanding. The consolidated financial statements of Noble-UK include the accounts of Noble-Cayman, and Noble-UK conducts substantially all of its business through Noble-Cayman and its subsidiaries. Principles of Consolidation The consolidated financial statements include our accounts, those of our wholly-owned subsidiaries and entities in which we hold a controlling financial interest. Our consolidated financial statements include the accounts of two joint ventures, in each of which we own a 50 percent interest. Our ownership interest meets the definition of variable interest under Financial Accounting Standards Board (“FASB”) codification and we have determined that we are the primary beneficiary. Intercompany balances and transactions have been eliminated in consolidation. Foreign Currency Translation Although we are a UK company, we define foreign currency as any non-U.S. denominated currency. In non-U.S. locations where the U.S. Dollar has been designated as the functional currency (based on an evaluation of factors including the markets in which the subsidiary operates, inflation, generation of cash flow, financing activities and intercompany arrangements), local currency transaction gains and losses are included in net income. In non-U.S. locations where the local currency is the functional currency, assets and liabilities are translated at the rates of exchange on the balance sheet date, while income statement items are translated at average rates of exchange during the year. The resulting gains or losses arising from the translation of accounts from the functional currency to the U.S. Dollar are included in “Accumulated other comprehensive loss” in the Consolidated Balance Sheets. We did not recognize any material gains or losses on foreign currency transactions or translations during the three years ended December 31, 2015. Cash and Cash Equivalents Cash and cash equivalents include cash on hand, demand deposits with banks and all highly liquid investments with original maturities of three months or less. Our cash, cash equivalents and short-term investments are subject to potential credit risk, and certain of our cash accounts carry balances greater than the federally insured limits. Cash and cash equivalents are primarily held by major banks or investment firms. Our cash management and investment policies restrict investments to lower risk, highly liquid securities and we perform periodic evaluations of the relative credit standing of the financial institutions with which we conduct business. Property and Equipment Property and equipment is stated at cost, reduced by provisions to recognize economic impairment in value whenever events or changes in circumstances indicate an asset’s carrying value may not be recoverable. Major replacements and improvements are capitalized. When assets are sold, retired or otherwise disposed of, the cost and related accumulated depreciation are eliminated from the accounts and the gain or loss is recognized. Drilling equipment and facilities are depreciated using the straight-line method over their estimated useful lives as of the date placed in service or date of major refurbishment. Estimated useful lives of our drilling equipment range from three to thirty years. Other property and equipment is depreciated using the straight-line method over useful lives ranging from two to forty years. Included in accounts payable were $44 million and $70 million of capital accruals as of December 31, 2015 and 2014, respectively. Interest is capitalized on construction-in-progress using the weighted average cost of debt outstanding during the period of construction. Scheduled maintenance of equipment is performed based on the number of hours operated in accordance with our preventative maintenance program. Routine repair and maintenance costs are charged to expense as incurred; however, the costs of the overhauls and asset replacement projects that benefit future periods and which typically occur every three to five years are capitalized when incurred and depreciated over an equivalent period. These overhauls and asset replacement projects are included in “Drilling equipment and facilities” in Note 7. Such amounts, net of accumulated depreciation, totaled $202 million and $179 million at December 31, 2015 and 2014, respectively. Depreciation expense from continuing operations related to overhauls and asset replacement totaled $75 million, $77 million and $70 million for the years ended December 31, 2015, 2014 and 2013, respectively. We evaluate the impairment of property and equipment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. In addition, on an annual basis, we complete an impairment analysis on our rig fleet. An impairment loss on our property and equipment exists when the estimated undiscounted cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. Any impairment loss recognized represents the excess of the asset’s carrying value over the estimated fair value. As part of this analysis, we make assumptions and estimates regarding future market conditions. To the extent actual results do not meet our estimated assumptions, for a given rig class, we may take an impairment loss in the future. For additional information, see Note 11. Deferred Costs Deferred debt issuance costs are being amortized through interest expense over the life of the debt securities. Revenue Recognition Our typical dayrate drilling contracts require our performance of a variety of services for a specified period of time. We determine progress towards completion of the contract by measuring efforts expended and the cost of services required to perform under a drilling contract, as the basis for our revenue recognition. Revenues generated from our dayrate-basis drilling contracts and labor contracts are recognized on a per day basis as services are performed and begin upon the contract commencement, as defined under the specified drilling or labor contract. Dayrate revenues are typically earned, and contract drilling expenses are typically incurred ratably over the term of our drilling contracts. We review and monitor our performance under our drilling contracts to confirm the basis for our revenue recognition. Revenues from bonuses are recognized when earned, and when collectability is reasonably assured. In our dayrate drilling contracts, we typically receive compensation and incur costs for mobilization, equipment modification or other activities prior to the commencement of a contract. Any such compensation may be paid through a lump-sum payment or other daily compensation. Pre-contract compensation and costs are deferred until the contract commences. The deferred pre-contract compensation and costs are amortized, using the straight-line method, into income over the term of the initial contract period, regardless of the activity taking place. This approach is consistent with the economics for which the parties have contracted. Once a contract commences, we may conduct various activities, including drilling and well bore related activities, rig maintenance and equipment installation, movement between well locations or other activities. Deferred revenues from drilling contracts totaled $180 million and $263 million at December 31, 2015 and 2014, respectively. Such amounts are included in either “Other current liabilities” or “Other liabilities” in the accompanying Consolidated Balance Sheets, based upon our expected time of recognition. Related expenses deferred under drilling contracts totaled $78 million at December 31, 2015 as compared to $94 million at December 31, 2014, and are included in either “Prepaid expenses and other current assets” or “Other assets” in the accompanying Consolidated Balance Sheets, based upon our expected time of recognition. In April 2015, we agreed to contract dayrate reductions for five rigs working for Saudi Arabian Oil Company (“Saudi Aramco”), which were effective from January 1, 2015 through December 31, 2015. However, given current market conditions and based on discussions with the customer, we do not expect the rates to return to the original contract rates. In accordance with accounting guidance, we are recognizing the reductions on a straight-line basis over the remaining life of the existing Saudi Aramco contracts. At December 31, 2015, revenues recorded in excess of billings as a result of this recognition totaled $53 million, and are included in either “Prepaid expenses and other current assets” or “Other assets” in the accompanying Consolidated Balance Sheets, based upon our expected time of recognition. We record reimbursements from customers for “out-of-pocket” expenses as revenues and the related direct cost as operating expenses. Income Taxes Income taxes are based on the laws and rates in effect in the countries in which operations are conducted or in which we or our subsidiaries are considered resident for income tax purposes. In certain circumstances, we expect that, due to changing demands of the offshore drilling markets and the ability to redeploy our offshore drilling units, certain of such units will not reside in a location long enough to give rise to future tax consequences. As a result, no deferred tax asset or liability has been recognized in these circumstances. Should our expectations change regarding the length of time an offshore drilling unit will be used in a given location, we will adjust deferred taxes accordingly. We operate through various subsidiaries in numerous countries throughout the world, including the United States. Consequently, we are subject to changes in tax laws, treaties or regulations or the interpretation or enforcement thereof in the U.S., UK or jurisdictions in which we or any of our subsidiaries operate or are resident. Our income tax expense is based upon our interpretation of the tax laws in effect in various countries at the time that the expense was incurred. If the U.S. Internal Revenue Service (“IRS”) or other taxing authorities do not agree with our assessment of the effects of such laws, treaties and regulations, this could have a material adverse effect on us including the imposition of a higher effective tax rate on our worldwide earnings or a reclassification of the tax impact of our significant corporate restructuring transactions. Insurance Reserves We maintain various levels of self-insured retention for certain losses including property damage, loss of hire, employment practices liability, employers’ liability and general liability, among others. We accrue for property damage and loss of hire charges on a per event basis. Employment practices liability claims are accrued based on actual claims during the year. Maritime employer’s liability claims are generally estimated using actuarial determinations. General liability claims are estimated by our internal claims department by evaluating the facts and circumstances of each claim (including incurred but not reported claims) and making estimates based upon historical experience with similar claims. At both December 31, 2015 and 2014, loss reserves for personal injury and protection claims totaled $21 million, and such amounts are included in “Other current liabilities” in the accompanying Consolidated Balance Sheets. Earnings per Share Our unvested share-based payment awards, which contain non-forfeitable rights to dividends, are participating securities and are included in the computation of earnings per share pursuant to the “two-class” method. The “two-class” method allocates undistributed earnings between common shares and participating securities. The diluted earnings per share calculation under the “two-class” method also includes the dilutive effect of potential shares issued in connection with stock options. The dilutive effect of stock options is determined using the treasury stock method. Share-Based Compensation Plans We record the grant date fair value of share-based compensation arrangements as compensation cost using a straight-line method over the service period. Share-based compensation is expensed or capitalized based on the nature of the employee’s activities. Certain Significant Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amount of revenues and expenses during the reporting period. Certain accounting policies involve judgments and uncertainties to such an extent that there is reasonable likelihood that materially different amounts could have been reported under different conditions, or if different assumptions had been used. We evaluate our estimates and assumptions on a regular basis. We base our estimates on historical experience and various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates and assumptions used in preparation of our consolidated financial statements. Accounting Pronouncements In April 2014, the FASB issued Accounting Standards Update (“ASU”) No. 2014-08, which amends FASB Accounting Standards Codification (“ASC”) Topic 205, “Presentation of Financial Statements” and ASC Topic 360, “Property, Plant, and Equipment.” This ASU alters the definition of a discontinued operation to cover only asset disposals that are a strategic shift with a major effect on an entity’s operations and finances, and calls for more extensive disclosures about a discontinued operation’s assets, liabilities, income and expenses. The guidance is effective for all disposals, or classifications as held-for-sale, of components of an entity that occur within annual periods beginning on or after December 15, 2014. This standard was not early adopted in connection with the Spin-off. The adoption of this guidance did not have a material impact on our financial condition, results of operations, cash flows or financial disclosures. In May 2014, the FASB issued ASU No. 2014-09, which creates ASC Topic 606, “Revenue from Contracts with Customers,” and supersedes the revenue recognition requirements in Topic 605, “Revenue Recognition,” including most industry-specific revenue recognition guidance throughout the Industry Topics of the Codification. In addition, ASU 2014-09 supersedes the cost guidance in Subtopic 605-35, “Revenue Recognition—Construction-Type and Production-Type Contracts,” and creates new Subtopic 340-40, “Other Assets and Deferred Costs—Contracts with Customers.” In summary, the core principle of Topic 606 is to recognize revenue when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. Companies are allowed to select between two transition methods: (1) a full retrospective transition method with the application of the new guidance to each prior reporting period presented, or (2) a retrospective transition method that recognizes the cumulative effect on prior periods at the date of adoption together with additional footnote disclosures. The amendments in ASU 2014-09 are effective for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period, and early application is not permitted. We are currently evaluating the impact the adoption of this guidance will have on our consolidated financial statements and have not made any decision on the method of adoption. In June 2014, the FASB issued ASU No. 2014-12, which amends ASC Topic 718, “Compensation-Stock Compensation.” The guidance requires that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition and should not be reflected in the estimate of the grant-date fair value of the award. The guidance is effective for annual periods beginning after December 15, 2015. The guidance can be applied prospectively for all awards granted or modified after the effective date or retrospectively to all awards with performance targets outstanding as of the beginning of the earliest annual period presented in the financial statements and to all new or modified awards thereafter. The adoption of this guidance is not anticipated to have a material impact on our financial condition, results of operations, cash flows or financial disclosures. In August 2014, the FASB issued ASU No. 2014-15, which amends ASC Subtopic 205-40, “Disclosure of Uncertainties about an Entity’s Ability to continue as a Going Concern.” The amendments in this ASU provide guidance related to management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. The amendments are effective for the annual period ending after December 15, 2016, and for annual periods and interim periods thereafter. The adoption of this guidance is not anticipated to have a material impact on our financial condition, results of operations, cash flows or financial disclosures. In January 2015, the FASB issued ASU No. 2015-01, which amends ASC Subtopic 225-20, “Income Statement – Extraordinary and Unusual Items.” The amendment in this ASU eliminates from GAAP the concept of extraordinary items. The amendments in this update are effective for interim and annual reporting periods beginning after December 15, 2015. The adoption of this guidance is not anticipated to have a material impact on our financial condition, results of operations, cash flows or financial disclosures. In February 2015, the FASB issued ASU No. 2015-02, which amends ASC Subtopic 810, “Consolidations.” This amendment affects reporting entities that are required to evaluate whether they should consolidate certain legal entities. Specifically, the amendments modify the evaluation of whether limited partnerships and similar legal entities are VIEs or voting interest entities; eliminate the presumption that a general partner should consolidate a limited partnership; affect the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships. The standard is effective for interim and annual reporting periods beginning after December 15, 2015. The standard may be applied retrospectively or through a cumulative effect adjustment to retained earnings as of the beginning of the year of adoption. We are evaluating what impact, if any, the adoption of this guidance will have on our financial condition, results of operations, cash flows or financial disclosures. In April 2015, the FASB issued ASU No. 2015-03, which amends ASC Subtopic 835-30, “Interest – Imputation of Interest.” The guidance requires debt issuance costs to be presented in the balance sheet as a direct reduction from the associated debt liability. The standard is effective for interim and annual reporting periods beginning after December 15, 2015. Early adoption is permitted for financial statements that have not been previously issued. The new guidance will be applied on a retrospective basis. In August 2015, the FASB issued ASU No. 2015-15 which amends ASC Subtopic 835-30, “Interest – Imputation of Interest.” The guidance allows a debt issuance cost related to a line-of-credit to be presented in the balance sheet as an asset and subsequently amortized ratably over the term of the line-of credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. We are evaluating what impact, if any, the adoption of this guidance will have on our financial condition, results of operations, cash flows or financial disclosures. In April 2015, the FASB issued ASU No. 2015-04, which amends ASC Topic 715, “Compensation – Retirement Benefits.” The guidance gives an employer whose fiscal year end does not coincide with a calendar month end the ability, as a practical expedient, to measure defined benefit retirement obligations and related plan assets as of the month end that is closest to its fiscal year end. The ASU also provides a similar practical expedient for interim remeasurements of significant events. The standard is effective for interim and annual reporting periods beginning after December 15, 2015. Early adoption is permitted. The adoption of this guidance is not anticipated to have a material impact on our financial condition, results of operations, cash flows or financial disclosures. In July 2015, the FASB issued ASU No. 2015-12, which amends ASC Topic 960, “Plan Accounting-Defined Benefit Pension Plans,” ASC Topic 962, “Defined Contribution Pension Plans” and ASC Topic 965, “Health and Welfare Benefit Plans.” There are three parts to the ASU that aim to simplify the accounting and presentation of plan accounting. Part I of this ASU requires fully benefit-responsive investment contracts to be measured at contract value instead of the current fair value measurement. Part II of this ASU requires investments (both participant-directed and nonparticipant-directed investments) of employee benefit plans be grouped only by general type, eliminating the need to disaggregate the investments in multiple ways. Part III of this ASU provides a similar measurement date practical expedient for employee benefit plans as available in ASU No. 2015-04, which allows employers to measure defined benefit plan assets on a month-end date that is nearest to the year’s fiscal year-end when the fiscal period does not coincide with a month-end. Parts I and II of the new guidance should be applied on a retrospective basis. Part III of the new guidance should be applied on a prospective basis. This guidance is effective for interim and annual reporting periods beginning after December 15, 2015. The adoption of this guidance is not anticipated to have a material impact on our financial condition, results of operations, cash flows or financial disclosures. In September 2015, the FASB issued ASU 2015-16, which amends Topic 805, “Business Combinations.” This amendment eliminates the requirement to retrospectively account for adjustments made to provisional amounts recognized in a business combination at the acquisition date with a corresponding adjustment to goodwill, and revise comparative information for prior periods presented in financial statements. Those adjustments are required when new information about circumstances that existed as of the acquisition date would have affected the measurement of the amount initially recognized. This update requires an entity to recognize these adjustments in the reporting period in which the adjustment amounts are determined. An acquirer must record the effect on earnings of changes in depreciation, amortization, or other income effects, calculated as if the accounting had been completed at the acquisition date. An entity must present separately on the face of the income statement, or disclose in the notes the portion of the amount recorded in current-period earnings by line item that would have been recorded in previous reporting periods if the adjustment had been recognized as of the acquisition date. This guidance is effective for interim and annual reporting periods beginning after December 15, 2015. The adoption of this guidance is not anticipated to have a material impact on our financial condition, results of operations, cash flows or financial disclosures. In November 2015, the FASB issued ASU No. 2015-17, which amends ASC Topic 740, “Income Taxes.” This amendment aligns the presentation of deferred income tax assets and liabilities with International Financial Reporting Standards. International Accounting Standard 1, Presentation of Financial Statements, requires deferred tax assets and liabilities to be classified as noncurrent in a classified statement of financial position. The current requirement that deferred tax liabilities and assets be offset and presented as a single amount is not affected by the amendments in this update. The standard is effective for interim and annual reporting periods beginning after December 15, 2016. Early adoption is permitted for all entities as of the beginning of an interim or annual reporting period. The amendments in this update may be applied either prospectively to all deferred tax liabilities and assets or retrospectively to all periods presented. We are evaluating what impact, if any, the adoption of this guidance will have on our financial condition, results of operations, cash flows or financial disclosures.

Note 1 - Organization and Significant Accounting Policies

Organization and Business

Noble Corporation plc, a public limited company incorporated under the laws of England and Wales (“Noble-UK”), is a leading offshore drilling contractor for the oil and gas industry. We perform contract drilling services with our global fleet of mobile offshore drilling units. As of the filing date of this Annual Report on Form 10-K, our fleet of 30 drilling rigs consisted of 14 jackups, eight drillships and eight semisubmersibles, including one high-specification, harsh environment jackup under construction.

At December 31, 2015, our fleet was located in the United States, Brazil, Argentina, the North Sea, the Mediterranean, West Africa, the Middle East, Asia and Australia. Noble and its predecessors have been engaged in the contract drilling of oil and gas wells since 1921.

On November 20, 2013, pursuant to the Merger Agreement dated as of June 30, 2013 between Noble Corporation, a Swiss corporation (“Noble-Swiss”), and Noble-UK, Noble-Swiss merged with and into Noble-UK, with Noble-UK as the surviving company (the “Transaction”). In the Transaction, all of the outstanding ordinary shares of Noble-Swiss were cancelled, and Noble-UK issued, through an exchange agent, one ordinary share of Noble-UK in exchange for each ordinary share of Noble-Swiss. The Transaction effectively changed the place of incorporation of our publicly traded parent holding company from Switzerland to the United Kingdom.

Noble Corporation, a Cayman Islands company (“Noble-Cayman”), is an indirect, wholly-owned subsidiary of Noble-UK, our publicly-traded parent company. Noble-UK’s principal asset is all of the shares of Noble-Cayman. Noble-Cayman has no public equity outstanding. The consolidated financial statements of Noble-UK include the accounts of Noble-Cayman, and Noble-UK conducts substantially all of its business through Noble-Cayman and its subsidiaries.

Principles of Consolidation

The consolidated financial statements include our accounts, those of our wholly-owned subsidiaries and entities in which we hold a controlling financial interest. Our consolidated financial statements include the accounts of two joint ventures, in each of which we own a 50 percent interest. Our ownership interest meets the definition of variable interest under Financial Accounting Standards Board (“FASB”) codification and we have determined that we are the primary beneficiary. Intercompany balances and transactions have been eliminated in consolidation.

Foreign Currency Translation

Although we are a UK company, we define foreign currency as any non-U.S. denominated currency. In non-U.S. locations where the U.S. Dollar has been designated as the functional currency (based on an evaluation of factors including the markets in which the subsidiary operates, inflation, generation of cash flow, financing activities and intercompany arrangements), local currency transaction gains and losses are included in net income. In non-U.S. locations where the local currency is the functional currency, assets and liabilities are translated at the rates of exchange on the balance sheet date, while income statement items are translated at average rates of exchange during the year. The resulting gains or losses arising from the translation of accounts from the functional currency to the U.S. Dollar are included in “Accumulated other comprehensive loss” in the Consolidated Balance Sheets. We did not recognize any material gains or losses on foreign currency transactions or translations during the three years ended December 31, 2015.

Cash and Cash Equivalents

Cash and cash equivalents include cash on hand, demand deposits with banks and all highly liquid investments with original maturities of three months or less. Our cash, cash equivalents and short-term investments are subject to potential credit risk, and certain of our cash accounts carry balances greater than the federally insured limits. Cash and cash equivalents are primarily held by major banks or investment firms. Our cash management and investment policies restrict investments to lower risk, highly liquid securities and we perform periodic evaluations of the relative credit standing of the financial institutions with which we conduct business.

Property and Equipment

Property and equipment is stated at cost, reduced by provisions to recognize economic impairment in value whenever events or changes in circumstances indicate an asset’s carrying value may not be recoverable. Major replacements and improvements are capitalized. When assets are sold, retired or otherwise disposed of, the cost and related accumulated depreciation are eliminated from the accounts and the gain or loss is recognized. Drilling equipment and facilities are depreciated using the straight-line method over their estimated useful lives as of the date placed in service or date of major refurbishment. Estimated useful lives of our drilling equipment range from three to thirty years. Other property and equipment is depreciated using the straight-line method over useful lives ranging from two to forty years. Included in accounts payable were $44 million and $70 million of capital accruals as of December 31, 2015 and 2014, respectively.

Interest is capitalized on construction-in-progress using the weighted average cost of debt outstanding during the period of construction.

Scheduled maintenance of equipment is performed based on the number of hours operated in accordance with our preventative maintenance program. Routine repair and maintenance costs are charged to expense as incurred; however, the costs of the overhauls and asset replacement projects that benefit future periods and which typically occur every three to five years are capitalized when incurred and depreciated over an equivalent period. These overhauls and asset replacement projects are included in “Drilling equipment and facilities” in Note 7. Such amounts, net of accumulated depreciation, totaled $202 million and $179 million at December 31, 2015 and 2014, respectively. Depreciation expense from continuing operations related to overhauls and asset replacement totaled $75 million, $77 million and $70 million for the years ended December 31, 2015, 2014 and 2013, respectively.

We evaluate the impairment of property and equipment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. In addition, on an annual basis, we complete an impairment analysis on our rig fleet. An impairment loss on our property and equipment exists when the estimated undiscounted cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. Any impairment loss recognized represents the excess of the asset’s carrying value over the estimated fair value. As part of this analysis, we make assumptions and estimates regarding future market conditions. To the extent actual results do not meet our estimated assumptions, for a given rig class, we may take an impairment loss in the future. For additional information, see Note 11.

Deferred Costs

Deferred debt issuance costs are being amortized through interest expense over the life of the debt securities.

Revenue Recognition

Our typical dayrate drilling contracts require our performance of a variety of services for a specified period of time. We determine progress towards completion of the contract by measuring efforts expended and the cost of services required to perform under a drilling contract, as the basis for our revenue recognition. Revenues generated from our dayrate-basis drilling contracts and labor contracts are recognized on a per day basis as services are performed and begin upon the contract commencement, as defined under the specified drilling or labor contract. Dayrate revenues are typically earned, and contract drilling expenses are typically incurred ratably over the term of our drilling contracts. We review and monitor our performance under our drilling contracts to confirm the basis for our revenue recognition. Revenues from bonuses are recognized when earned, and when collectability is reasonably assured.

In our dayrate drilling contracts, we typically receive compensation and incur costs for mobilization, equipment modification or other activities prior to the commencement of a contract. Any such compensation may be paid through a lump-sum payment or other daily compensation. Pre-contract compensation and costs are deferred until the contract commences. The deferred pre-contract compensation and costs are amortized, using the straight-line method, into income over the term of the initial contract period, regardless of the activity taking place. This approach is consistent with the economics for which the parties have contracted. Once a contract commences, we may conduct various activities, including drilling and well bore related activities, rig maintenance and equipment installation, movement between well locations or other activities.

Deferred revenues from drilling contracts totaled $180 million and $263 million at December 31, 2015 and 2014, respectively. Such amounts are included in either “Other current liabilities” or “Other liabilities” in the accompanying Consolidated Balance Sheets, based upon our expected time of recognition. Related expenses deferred under drilling contracts totaled $78 million at December 31, 2015 as compared to $94 million at December 31, 2014, and are included in either “Prepaid expenses and other current assets” or “Other assets” in the accompanying Consolidated Balance Sheets, based upon our expected time of recognition.

In April 2015, we agreed to contract dayrate reductions for five rigs working for Saudi Arabian Oil Company (“Saudi Aramco”), which were effective from January 1, 2015 through December 31, 2015. However, given current market conditions and based on discussions with the customer, we do not expect the rates to return to the original contract rates. In accordance with accounting guidance, we are recognizing the reductions on a straight-line basis over the remaining life of the existing Saudi Aramco contracts. At December 31, 2015, revenues recorded in excess of billings as a result of this recognition totaled $53 million, and are included in either “Prepaid expenses and other current assets” or “Other assets” in the accompanying Consolidated Balance Sheets, based upon our expected time of recognition.

We record reimbursements from customers for “out-of-pocket” expenses as revenues and the related direct cost as operating expenses.

Income Taxes

Income taxes are based on the laws and rates in effect in the countries in which operations are conducted or in which we or our subsidiaries are considered resident for income tax purposes. In certain circumstances, we expect that, due to changing demands of the offshore drilling markets and the ability to redeploy our offshore drilling units, certain of such units will not reside in a location long enough to give rise to future tax consequences. As a result, no deferred tax asset or liability has been recognized in these circumstances. Should our expectations change regarding the length of time an offshore drilling unit will be used in a given location, we will adjust deferred taxes accordingly.

We operate through various subsidiaries in numerous countries throughout the world, including the United States. Consequently, we are subject to changes in tax laws, treaties or regulations or the interpretation or enforcement thereof in the U.S., UK or jurisdictions in which we or any of our subsidiaries operate or are resident. Our income tax expense is based upon our interpretation of the tax laws in effect in various countries at the time that the expense was incurred. If the U.S. Internal Revenue Service (“IRS”) or other taxing authorities do not agree with our assessment of the effects of such laws, treaties and regulations, this could have a material adverse effect on us including the imposition of a higher effective tax rate on our worldwide earnings or a reclassification of the tax impact of our significant corporate restructuring transactions.

Insurance Reserves

We maintain various levels of self-insured retention for certain losses including property damage, loss of hire, employment practices liability, employers’ liability and general liability, among others. We accrue for property damage and loss of hire charges on a per event basis.

Employment practices liability claims are accrued based on actual claims during the year. Maritime employer’s liability claims are generally estimated using actuarial determinations. General liability claims are estimated by our internal claims department by evaluating the facts and circumstances of each claim (including incurred but not reported claims) and making estimates based upon historical experience with similar claims. At both December 31, 2015 and 2014, loss reserves for personal injury and protection claims totaled $21 million, and such amounts are included in “Other current liabilities” in the accompanying Consolidated Balance Sheets.

Earnings per Share

Our unvested share-based payment awards, which contain non-forfeitable rights to dividends, are participating securities and are included in the computation of earnings per share pursuant to the “two-class” method. The “two-class” method allocates undistributed earnings between common shares and participating securities. The diluted earnings per share calculation under the “two-class” method also includes the dilutive effect of potential shares issued in connection with stock options. The dilutive effect of stock options is determined using the treasury stock method.

Share-Based Compensation Plans

We record the grant date fair value of share-based compensation arrangements as compensation cost using a straight-line method over the service period. Share-based compensation is expensed or capitalized based on the nature of the employee’s activities.

Certain Significant Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amount of revenues and expenses during the reporting period. Certain accounting policies involve judgments and uncertainties to such an extent that there is reasonable likelihood that materially different amounts could have been reported under different conditions, or if different assumptions had been used. We evaluate our estimates and assumptions on a regular basis. We base our estimates on historical experience and various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates and assumptions used in preparation of our consolidated financial statements.

Accounting Pronouncements

In April 2014, the FASB issued Accounting Standards Update (“ASU”) No. 2014-08, which amends FASB Accounting Standards Codification (“ASC”) Topic 205, “Presentation of Financial Statements” and ASC Topic 360, “Property, Plant, and Equipment.” This ASU alters the definition of a discontinued operation to cover only asset disposals that are a strategic shift with a major effect on an entity’s operations and finances, and calls for more extensive disclosures about a discontinued operation’s assets, liabilities, income and expenses. The guidance is effective for all disposals, or classifications as held-for-sale, of components of an entity that occur within annual periods beginning on or after December 15, 2014. This standard was not early adopted in connection with the Spin-off. The adoption of this guidance did not have a material impact on our financial condition, results of operations, cash flows or financial disclosures.

In May 2014, the FASB issued ASU No. 2014-09, which creates ASC Topic 606, “Revenue from Contracts with Customers,” and supersedes the revenue recognition requirements in Topic 605, “Revenue Recognition,” including most industry-specific revenue recognition guidance throughout the Industry Topics of the Codification. In addition, ASU 2014-09 supersedes the cost guidance in Subtopic 605-35, “Revenue Recognition—Construction-Type and Production-Type Contracts,” and creates new Subtopic 340-40, “Other Assets and Deferred Costs—Contracts with Customers.” In summary, the core principle of Topic 606 is to recognize revenue when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. Companies are allowed to select between two transition methods: (1) a full retrospective transition method with the application of the new guidance to each prior reporting period presented, or (2) a retrospective transition method that recognizes the cumulative effect on prior periods at the date of adoption together with additional footnote disclosures. The amendments in ASU 2014-09 are effective for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period, and early application is not permitted. We are currently evaluating the impact the adoption of this guidance will have on our consolidated financial statements and have not made any decision on the method of adoption.

In June 2014, the FASB issued ASU No. 2014-12, which amends ASC Topic 718, “Compensation-Stock Compensation.” The guidance requires that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition and should not be reflected in the estimate of the grant-date fair value of the award. The guidance is effective for annual periods beginning after December 15, 2015. The guidance can be applied prospectively for all awards granted or modified after the effective date or retrospectively to all awards with performance targets outstanding as of the beginning of the earliest annual period presented in the financial statements and to all new or modified awards thereafter. The adoption of this guidance is not anticipated to have a material impact on our financial condition, results of operations, cash flows or financial disclosures.

In August 2014, the FASB issued ASU No. 2014-15, which amends ASC Subtopic 205-40, “Disclosure of Uncertainties about an Entity’s Ability to continue as a Going Concern.” The amendments in this ASU provide guidance related to management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. The amendments are effective for the annual period ending after December 15, 2016, and for annual periods and interim periods thereafter. The adoption of this guidance is not anticipated to have a material impact on our financial condition, results of operations, cash flows or financial disclosures.

In January 2015, the FASB issued ASU No. 2015-01, which amends ASC Subtopic 225-20, “Income Statement – Extraordinary and Unusual Items.” The amendment in this ASU eliminates from GAAP the concept of extraordinary items. The amendments in this update are effective for interim and annual reporting periods beginning after December 15, 2015. The adoption of this guidance is not anticipated to have a material impact on our financial condition, results of operations, cash flows or financial disclosures.

In February 2015, the FASB issued ASU No. 2015-02, which amends ASC Subtopic 810, “Consolidations.” This amendment affects reporting entities that are required to evaluate whether they should consolidate certain legal entities. Specifically, the amendments modify the evaluation of whether limited partnerships and similar legal entities are VIEs or voting interest entities; eliminate the presumption that a general partner should consolidate a limited partnership; affect the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships. The standard is effective for interim and annual reporting periods beginning after December 15, 2015. The standard may be applied retrospectively or through a cumulative effect adjustment to retained earnings as of the beginning of the year of adoption. We are evaluating what impact, if any, the adoption of this guidance will have on our financial condition, results of operations, cash flows or financial disclosures.

In April 2015, the FASB issued ASU No. 2015-03, which amends ASC Subtopic 835-30, “Interest – Imputation of Interest.” The guidance requires debt issuance costs to be presented in the balance sheet as a direct reduction from the associated debt liability. The standard is effective for interim and annual reporting periods beginning after December 15, 2015. Early adoption is permitted for financial statements that have not been previously issued. The new guidance will be applied on a retrospective basis. In August 2015, the FASB issued ASU No. 2015-15 which amends ASC Subtopic 835-30, “Interest – Imputation of Interest.” The guidance allows a debt issuance cost related to a line-of-credit to be presented in the balance sheet as an asset and subsequently amortized ratably over the term of the line-of credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. We are evaluating what impact, if any, the adoption of this guidance will have on our financial condition, results of operations, cash flows or financial disclosures.

In April 2015, the FASB issued ASU No. 2015-04, which amends ASC Topic 715, “Compensation – Retirement Benefits.” The guidance gives an employer whose fiscal year end does not coincide with a calendar month end the ability, as a practical expedient, to measure defined benefit retirement obligations and related plan assets as of the month end that is closest to its fiscal year end. The ASU also provides a similar practical expedient for interim remeasurements of significant events. The standard is effective for interim and annual reporting periods beginning after December 15, 2015. Early adoption is permitted. The adoption of this guidance is not anticipated to have a material impact on our financial condition, results of operations, cash flows or financial disclosures.

In July 2015, the FASB issued ASU No. 2015-12, which amends ASC Topic 960, “Plan Accounting-Defined Benefit Pension Plans,” ASC Topic 962, “Defined Contribution Pension Plans” and ASC Topic 965, “Health and Welfare Benefit Plans.” There are three parts to the ASU that aim to simplify the accounting and presentation of plan accounting. Part I of this ASU requires fully benefit-responsive investment contracts to be measured at contract value instead of the current fair value measurement. Part II of this ASU requires investments (both participant-directed and nonparticipant-directed investments) of employee benefit plans be grouped only by general type, eliminating the need to disaggregate the investments in multiple ways. Part III of this ASU provides a similar measurement date practical expedient for employee benefit plans as available in ASU No. 2015-04, which allows employers to measure defined benefit plan assets on a month-end date that is nearest to the year’s fiscal year-end when the fiscal period does not coincide with a month-end. Parts I and II of the new guidance should be applied on a retrospective basis. Part III of the new guidance should be applied on a prospective basis. This guidance is effective for interim and annual reporting periods beginning after December 15, 2015. The adoption of this guidance is not anticipated to have a material impact on our financial condition, results of operations, cash flows or financial disclosures.

In September 2015, the FASB issued ASU 2015-16, which amends Topic 805, “Business Combinations.” This amendment eliminates the requirement to retrospectively account for adjustments made to provisional amounts recognized in a business combination at the acquisition date with a corresponding adjustment to goodwill, and revise comparative information for prior periods presented in financial statements. Those adjustments are required when new information about circumstances that existed as of the acquisition date would have affected the measurement of the amount initially recognized. This update requires an entity to recognize these adjustments in the reporting period in which the adjustment amounts are determined. An acquirer must record the effect on earnings of changes in depreciation, amortization, or other income effects, calculated as if the accounting had been completed at the acquisition date. An entity must present separately on the face of the income statement, or disclose in the notes the portion of the amount recorded in current-period earnings by line item that would have been recorded in previous reporting periods if the adjustment had been recognized as of the acquisition date. This guidance is effective for interim and annual reporting periods beginning after December 15, 2015. The adoption of this guidance is not anticipated to have a material impact on our financial condition, results of operations, cash flows or financial disclosures.

In November 2015, the FASB issued ASU No. 2015-17, which amends ASC Topic 740, “Income Taxes.” This amendment aligns the presentation of deferred income tax assets and liabilities with International Financial Reporting Standards. International Accounting Standard 1, Presentation of Financial Statements, requires deferred tax assets and liabilities to be classified as noncurrent in a classified statement of financial position. The current requirement that deferred tax liabilities and assets be offset and presented as a single amount is not affected by the amendments in this update. The standard is effective for interim and annual reporting periods beginning after December 15, 2016. Early adoption is permitted for all entities as of the beginning of an interim or annual reporting period. The amendments in this update may be applied either prospectively to all deferred tax liabilities and assets or retrospectively to all periods presented. We are evaluating what impact, if any, the adoption of this guidance will have on our financial condition, results of operations, cash flows or financial disclosures.