Organization and Significant Accounting Policies	12 Months Ended
Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Significant Accounting Policies	Note 1— Organization and Significant Accounting Policies 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 provide contract drilling services to the international oil and gas industry with our global fleet of mobile offshore drilling units. As of December 31, 2019, our fleet of 25 drilling rigs consisted of 12 floaters and 13 jackups. We report our contract drilling operations as a single reportable segment, Contract Drilling Services, which reflects how we manage our business. The mobile offshore drilling units comprising our offshore rig fleet operate in a global market for contract drilling services and are often redeployed to different regions due to changing demands of our customers, which consist primarily of large, integrated, independent and government-owned or controlled oil and gas companies throughout the world. 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. Beginning in 2019, we combined the semisubmersibles and drillships in our contract drilling services fleet into a single category, floaters, for reporting purposes. We have made certain reclassifications to prior year so as to conform to such current period presentation. The reclassification did not have a material effect on our Condensed Consolidated Statements of Operations or related disclosures. Principles of Consolidation The consolidated financial statements include our accounts and those of our wholly-owned subsidiaries and entities in which we hold a controlling financial interest. Until December 3, 2019 our consolidated financial statements included the accounts of two joint ventures, in each of which we owned a 50 percent interest. On December 3, 2019, we acquired the remaining 50 percent interest not owned by us and as a result the two joint ventures became our wholly-owned subsidiaries. Our historical ownership interest in the joint ventures met the definition of variable interest under Financial Accounting Standards Board (“FASB”) codification and we determined that we were the primary beneficiary. Intercompany balances and transactions have been eliminated in consolidation. The combined carrying amount of the Bully-class drillships at December 31, 2018 totaled $0.7 billion. These assets were primarily funded through partner equity contributions. Cash held by the Bully joint ventures totaled approximately $45.2 million at December 31, 2018. Foreign Currency Translation Although we are a UK company, our functional currency is the US dollar, and we define any non-US dollar denominated currency as “foreign currencies.” In non-US locations where the US 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 or loss. In non-US 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 statement of operations 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 US 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, 2019. 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. Restricted Cash We classify restricted cash balances in current assets if the restriction is expected to expire or otherwise be resolved within one year and in other assets if the restriction is expected to expire or otherwise be resolved in more than one year. As of December 31, 2019 and 2018, our restricted cash balance consisted of $1.3 million and $0.7 million, respectively, associated with our financing of the Noble Johnny Whitstine and Noble Joe Knight, recorded in Prepaid expenses and other current assets. Accounts Receivable We record accounts receivable at the amount we invoice our clients, net of allowance for doubtful accounts. We provide an allowance for uncollectible accounts, as necessary. Our allowance for doubtful accounts as of December 31, 2019 and 2018 was $1.9 million and $2.2 million, respectively. Property and Equipment Property and equipment is stated at cost, reduced by provisions to recognize economic impairment. 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 $36.0 million and $52.1 million of capital accruals as of December 31, 2019 and 2018, respectively. Interest is capitalized on long-term construction project 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 5— Property and Equipment.” We evaluate our property and equipment for impairment whenever there are changes in facts that suggest that the value of the asset is not recoverable. For more detailed information, see “Note 6— Loss on Impairment.” Fair Value Measurements We measure certain of our assets and liabilities based on a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The three-level hierarchy, from highest to lowest level of observable inputs, are as follows: Level 1 - Valuations based on quoted prices in active markets for identical assets; Level 2 - Valuations based on observable inputs that do not meet the criteria for Level 1, including quoted prices in inactive markets and quoted prices in active markets for similar but not identical instruments; and Level 3 - Valuations based on unobservable inputs. Revenue Recognition The activities that primarily drive the revenue earned in our drilling contracts include (i) providing a drilling rig and the crew and supplies necessary to operate the rig, (ii) mobilizing and demobilizing the rig to and from the drill site, and (iii) performing rig preparation activities and/or modifications required for the contract. Consideration received for performing these activities may consist of dayrate drilling revenue, mobilization and demobilization revenue, contract preparation revenue and reimbursement revenue. We account for these integrated services provided within our drilling contracts as a single performance obligation satisfied over time and comprised of a series of distinct time increments in which we provide drilling services. Our standard drilling contracts require that we operate the rig at the direction of the customer throughout the contract term (which is the period we estimate to benefit from the corresponding activities and generally ranges from two to 60 months). The activities performed and the level of service provided can vary hour to hour. Our obligation under a standard contract is to provide whatever level of service is required by the operator, or customer, over the term of the contract. We are, therefore, under a stand-ready obligation throughout the entire contract duration. Consideration for our stand-ready obligation corresponds to distinct time increments, though the rate may be variable depending on various factors, and is recognized in the period in which the services are performed. The total transaction price is determined for each individual contract by estimating both fixed and variable consideration expected to be earned over the term of the contract. We have elected to exclude from the transaction price measurement all taxes assessed by a governmental authority. See further discussion regarding the allocation of the transaction price to the remaining performance obligations below. The amount estimated for variable consideration may be subject to interrupted or restricted rates and is only included in the transaction price to the extent that it is probable that a significant reversal of previously recognized revenue will not occur throughout the term of the contract (“constrained revenue”). When determining if variable consideration should be constrained, management considers whether there are factors outside the Company’s control that could result in a significant reversal of revenue as well as the likelihood and magnitude of a potential reversal of revenue. These estimates are re-assessed each reporting period as required. Dayrate Drilling Revenue. Our drilling contracts generally provide for payment on a dayrate basis, with higher rates for periods when the drilling unit is operating and lower rates or zero rates for periods when drilling operations are interrupted or restricted. The dayrate invoices billed to the customer are typically determined based on the varying rates applicable to the specific activities performed on an hourly basis. Such dayrate consideration is allocated to the distinct hourly increment it relates to within the contract term, and therefore, recognized in line with the contractual rate billed for the services provided for any given hour. Mobilization/Demobilization Revenue. We may receive fees (on either a fixed lump-sum or variable dayrate basis) for the mobilization and demobilization of our rigs. These activities are not considered to be distinct within the context of the contract and, therefore, the associated revenue is allocated to the overall performance obligation and the associated pre-operating costs are deferred. We record a contract liability for mobilization fees received and a deferred asset for costs. Both revenue and pre-operating costs are recognized ratably over the initial term of the related drilling contract. In most contracts, there is uncertainty as to the amount of expected demobilization revenue due to contractual provisions that stipulate that certain conditions must be present at contract completion for such revenue to be received and as to the amount thereof, if any. For example, contractual provisions may require that a rig demobilize a certain distance before the demobilization revenue is payable or the amount may vary dependent upon whether or not the rig has additional contracted work within a certain distance from the wellsite. Therefore, the estimate for such revenue may be constrained, as described earlier, depending on the facts and circumstances pertaining to the specific contract. We assess the likelihood of receiving such revenue based on past experience and knowledge of the market conditions. In cases where demobilization revenue is expected to be received upon contract completion, it is estimated as part of the overall transaction price at contract inception and recognized in earnings ratably over the initial term of the contract with an offset to an accretive contract asset. Contract Preparation Revenue. Some of our drilling contracts require downtime before the start of the contract to prepare the rig to meet customer requirements. At times, we may be compensated by the customer for such work (on either a fixed lump-sum or variable dayrate basis). These activities are not considered to be distinct within the context of the contract and, therefore, the related revenue is allocated to the overall performance obligation and recognized ratably over the initial term of the related drilling contract. We record a contract liability for contract preparation fees received, which is amortized ratably to contract drilling revenue over the initial term of the related drilling contract. Bonuses, Penalties and Other Variable Consideration. We may receive bonus increases to revenue or penalty decreases to revenue. Based on historical data and ongoing communication with the operator/customer, we are able to reasonably estimate this variable consideration. We will record such estimated variable consideration and re-measure our estimates at each reporting date. For revenue estimated, but not received, we will record to “Prepaid expenses and other current assets” on our Consolidated Balance Sheets. Capital Modification Revenue. From time to time, we may receive fees from our customers for capital improvements to our rigs to meet contractual requirements (on either a fixed lump-sum or variable dayrate basis). Such revenue is allocated to the overall performance obligation and recognized ratably over the initial term of the related drilling contract as these activities are integral to our drilling activities and are not considered to be a stand-alone service provided to the customer within the context of our contracts. We record a contract liability for such fees and recognize them ratably as contract drilling revenue over the initial term of the related drilling contract. Revenues Related to Reimbursable Expenses. We generally receive reimbursements from our customers for the purchase of supplies, equipment, personnel services and other services provided at their request in accordance with a drilling contract or other agreement. Such reimbursable revenue is variable and subject to uncertainty, as the amounts received and timing thereof is highly dependent on factors outside of our influence. Accordingly, reimbursable revenue is constrained revenue and not included in the total transaction price until the uncertainty is resolved, which typically occurs when the related costs are incurred on behalf of a customer. We are generally considered a principal in such transactions and record the associated revenue at the gross amount billed to the customer as “Reimbursables and other” in our Consolidated Statements of Operations. Such amounts are recognized ratably over the period within the contract term during which the corresponding goods and services are to be consumed. Deferred revenues from drilling contracts totaled $65.1 million and $80.8 million at December 31, 2019 and 2018, 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 $30.8 million at December 31, 2019 as compared to $47.7 million at December 31, 2018 and are included in either “Prepaid expenses and other current assets,” “Other assets” or “Property and equipment, net” 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. Deferred tax assets and liabilities are recognized for the anticipated future tax effects of temporary differences between the financial statement basis and the tax basis of our assets and liabilities using the applicable jurisdictional tax rates at year-end. A valuation allowance for deferred tax assets is recorded when it is more likely than not that the deferred tax asset will not be realized in a future period. 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 United States, UK and any other 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 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. The Company has adopted an accounting policy to look through the outside basis of partnerships and all other flow-through entities and exclude these from the computation of deferred taxes. 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 December 31, 2019 and 2018, loss reserves for personal injury and protection claims totaled $27.9 million and $22.4 million, respectively, 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. Litigation Contingencies We are involved in legal proceedings, claims, and regulatory, tax or government inquiries and investigations that arise in the ordinary course of business. Certain of these matters include speculative claims for substantial or indeterminate amounts of damages. We record a liability when we believe that it is both probable that a loss has been incurred and the amount can be reasonably estimated. If we determine that a loss is reasonably possible and the loss or range of loss can be estimated, we disclose the possible loss in the notes to the consolidated financial statements. We review the developments in our contingencies that could affect the amount of the provisions that has been previously recorded, and the matters and related possible losses disclosed. We make adjustments to our provisions and changes to our disclosures accordingly to reflect the impact of negotiations, settlements, rulings, advice of legal counsel, and updated information. Significant judgement is required to determine both the probability and the estimated amount. Discontinued Operations On August 1, 2014, Noble-UK completed the separation and spin-off of a majority of its standard specification offshore drilling business (the “Spin-off”) through a pro rata distribution of all of the ordinary shares of its wholly-owned subsidiary, Paragon Offshore plc (“Paragon Offshore”), to the holders of Noble’s ordinary shares. Paragon Offshore, which had been reflected as continuing operations in our consolidated financial statements prior to the Spin-off, meets the criteria for being reported as discontinued operations and has been reclassified as such in our results of operations. Prior to the completion of the Spin-off, Noble-UK and Paragon Offshore entered into a series of agreements to effect the separation and Spin-off and govern the relationship between the parties after the Spin-off (the “Separation Agreements”), including the Master Separation Agreement (the “MSA”) and the Tax Sharing Agreement (the “TSA”). During the year ended December 31, 2017, we recorded a non-cash loss of $1.5 million in “Net loss from discontinued operations, net of tax” on our Consolidated Statement of Operations from the effects of Paragon Offshore's rejection of the Separation Agreements. During the year ended December 31, 2019, we recognized charges of $3.8 million recorded in “Net loss from discontinued operations, net of tax” on our Consolidated Statement of Operations relating to settlement of Mexico customs audits from rigs included in the Spin-off. For additional information related to the Spin-off, refer to “Note 16— Commitments and Contingencies.” Certain Significant Estimates The preparation of financial statements in conformity with 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 Accounting Standards Adopted In February 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-02 (Topic 842, “Leases”), as amended, which generally requires lessees to recognize operating and financing lease liabilities and corresponding right-of-use assets on the balance sheet and to provide enhanced disclosures surrounding the amount, time and uncertainty of cash flows arising from lease agreements. We adopted this standard, on a modified retrospective basis, effective January 1, 2019 and did not restate comparative periods. Our adoption did not have a material effect on our consolidated financial statements. With respect to leases in which we are the lessee, we recognized a lease liability and a corresponding right-of-use asset of approximately $28.0 million on our Consolidated Balance Sheet as of January 1, 2019. We have elected the package of practical expedients that permits us to not reassess (1) whether previously expired or existing contracts are or contain leases, (2) the lease classification for any expired or existing leases, and (3) any initial direct costs for any existing leases as of the effective date. In addition, we have elected the hindsight practical expedient in connection with our adoption of the new lease standard. As lessee, we have made the accounting policy election to not recognize a right-of-use asset lease and lease liability for leases with a term of 12 months or less. We will recognize lease payments in the Consolidated Statements of Operations on a straight-line basis over the lease term. We have also elected the practical expedient to not separate lease and non-lease components. Our drilling contracts contain a lease component related to the underlying drilling equipment, in addition to the service component provided by our crews and our expertise to operate such drilling equipment. We have concluded the non-lease service of operating our equipment and providing expertise in the drilling of the client’s well is predominant in our drilling contracts. We have applied the practical expedient to account for the lease and associated nonlease components as a single component. With the election of the practical expedient, we will continue to present a single performance obligation under the new revenue guidance in Accounting Standards Codification (“ASC”) Topic 606, “Revenue from Contracts with Customers.” Recently Issued Accounting Standards In December 2019, the FASB issued ASU No. 2019-12, which amends ASC Subtopic 740, “Income Taxes” This update simplifies the accounting for income taxes by removing certain exceptions to general principles. The amendment is effective for fiscal years beginning after December 15, 2020 and is required to be adopted on a retrospective basis for all periods presented. We are evaluating what impact, if any, the adoption of this guidance will have on our consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-14, which amends ASC Subtopic 715-20, “Compensation — Retirement Benefits — Defined Benefit Plans — General.” This update applies to all employers that sponsor defined benefit pension or other postretirement plans and is part of the disclosure framework project to improve the effectiveness of disclosures in notes to the financial statements. The amendment is effective for fiscal years ending after December 15, 2020 and is required to be adopted on a retrospective basis for all periods presented. We do not expect the adoption of this guidance to materially affect our consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13 (Topic 326, “Measurement of Credit Losses on Financial Instruments”), which requires changes to the recognition of credit losses on financial instruments not accounted for at fair value through net income, including loans, debt securities, trade receivables, net investments in leases and available-for-sale debt securities. This guidance will be effective for annual and interim periods beginning after December 15, 2019. Entities are required to apply the standard’s provisions as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. We do not expect the adoption of this guidance to materially affect our consolidated financial statements. With the exception of the updated standards discussed above, there have been no new accounting pronouncements not yet effective that have significance, or potential significance, to our consolidated financial statements.

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 provide contract drilling services to the international oil and gas industry with our global fleet of mobile offshore drilling units. As of December 31, 2019, our fleet of 25 drilling rigs consisted of 12 floaters and 13 jackups.

We report our contract drilling operations as a single reportable segment, Contract Drilling Services, which reflects how we manage our business. The mobile offshore drilling units comprising our offshore rig fleet operate in a global market for contract drilling services and are often redeployed to different regions due to changing demands of our customers, which consist primarily of large, integrated, independent and government-owned or controlled oil and gas companies throughout the world.

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.

Beginning in 2019, we combined the semisubmersibles and drillships in our contract drilling services fleet into a single category, floaters, for reporting purposes. We have made certain reclassifications to prior year so as to conform to such current period presentation. The reclassification did not have a material effect on our Condensed Consolidated Statements of Operations or related disclosures.

The consolidated financial statements include our accounts and those of our wholly-owned subsidiaries and entities in which we hold a controlling financial interest. Until December 3, 2019 our consolidated financial statements included the accounts of two joint ventures, in each of which we owned a 50 percent interest. On December 3, 2019, we acquired the remaining 50 percent interest not owned by us and as a result the two joint ventures became our wholly-owned subsidiaries. Our historical ownership interest in the joint ventures met the definition of variable interest under Financial Accounting Standards Board (“FASB”) codification and we determined that we were the primary beneficiary. Intercompany balances and transactions have been eliminated in consolidation.

The combined carrying amount of the Bully-class drillships at December 31, 2018 totaled $0.7 billion. These assets were primarily funded through partner equity contributions. Cash held by the Bully joint ventures totaled approximately $45.2 million at December 31, 2018.

Although we are a UK company, our functional currency is the US dollar, and we define any non-US dollar denominated currency as “foreign currencies.” In non-US locations where the US 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 or loss. In non-US 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 statement of operations 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 US 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, 2019.

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.

We classify restricted cash balances in current assets if the restriction is expected to expire or otherwise be resolved within one year and in other assets if the restriction is expected to expire or otherwise be resolved in more than one year. As of December 31, 2019 and 2018, our restricted cash balance consisted of $1.3 million and $0.7 million, respectively, associated with our financing of the Noble Johnny Whitstine and Noble Joe Knight, recorded in Prepaid expenses and other current assets.

We record accounts receivable at the amount we invoice our clients, net of allowance for doubtful accounts. We provide an allowance for uncollectible accounts, as necessary. Our allowance for doubtful accounts as of December 31, 2019 and 2018 was $1.9 million and $2.2 million, respectively.

Property and equipment is stated at cost, reduced by provisions to recognize economic impairment. 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 $36.0 million and $52.1 million of capital accruals as of December 31, 2019 and 2018, respectively.

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 5— Property and Equipment.”

We measure certain of our assets and liabilities based on a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The three-level hierarchy, from highest to lowest level of observable inputs, are as follows:

The activities that primarily drive the revenue earned in our drilling contracts include (i) providing a drilling rig and the crew and supplies necessary to operate the rig, (ii) mobilizing and demobilizing the rig to and from the drill site, and (iii) performing rig preparation activities and/or modifications required for the contract. Consideration received for performing these activities may consist of dayrate drilling revenue, mobilization and demobilization revenue, contract preparation revenue and reimbursement revenue. We account for these integrated services provided within our drilling contracts as a single performance obligation satisfied over time and comprised of a series of distinct time increments in which we provide drilling services.

Our standard drilling contracts require that we operate the rig at the direction of the customer throughout the contract term (which is the period we estimate to benefit from the corresponding activities and generally ranges from two to 60 months). The activities performed and the level of service provided can vary hour to hour. Our obligation under a standard contract is to provide whatever level of service is required by the operator, or customer, over the term of the contract. We are, therefore, under a stand-ready obligation throughout the entire contract duration. Consideration for our stand-ready obligation corresponds to distinct time increments, though the rate may be variable depending on various factors,

and is recognized in the period in which the services are performed. The total transaction price is determined for each individual contract by estimating both fixed and variable consideration expected to be earned over the term of the contract. We have elected to exclude from the transaction price measurement all taxes assessed by a governmental authority. See further discussion regarding the allocation of the transaction price to the remaining performance obligations below.

The amount estimated for variable consideration may be subject to interrupted or restricted rates and is only included in the transaction price to the extent that it is probable that a significant reversal of previously recognized revenue will not occur throughout the term of the contract (“constrained revenue”). When determining if variable consideration should be constrained, management considers whether there are factors outside the Company’s control that could result in a significant reversal of revenue as well as the likelihood and magnitude of a potential reversal of revenue. These estimates are re-assessed each reporting period as required.

Dayrate Drilling Revenue. Our drilling contracts generally provide for payment on a dayrate basis, with higher rates for periods when the drilling unit is operating and lower rates or zero rates for periods when drilling operations are interrupted or restricted. The dayrate invoices billed to the customer are typically determined based on the varying rates applicable to the specific activities performed on an hourly basis. Such dayrate consideration is allocated to the distinct hourly increment it relates to within the contract term, and therefore, recognized in line with the contractual rate billed for the services provided for any given hour.

Mobilization/Demobilization Revenue. We may receive fees (on either a fixed lump-sum or variable dayrate basis) for the mobilization and demobilization of our rigs. These activities are not considered to be distinct within the context of the contract and, therefore, the associated revenue is allocated to the overall performance obligation and the associated pre-operating costs are deferred. We record a contract liability for mobilization fees received and a deferred asset for costs. Both revenue and pre-operating costs are recognized ratably over the initial term of the related drilling contract.

In most contracts, there is uncertainty as to the amount of expected demobilization revenue due to contractual provisions that stipulate that certain conditions must be present at contract completion for such revenue to be received and as to the amount thereof, if any. For example, contractual provisions may require that a rig demobilize a certain distance before the demobilization revenue is payable or the amount may vary dependent upon whether or not the rig has additional contracted work within a certain distance from the wellsite. Therefore, the estimate for such revenue may be constrained, as described earlier, depending on the facts and circumstances pertaining to the specific contract. We assess the likelihood of receiving such revenue based on past experience and knowledge of the market conditions. In cases where demobilization revenue is expected to be received upon contract completion, it is estimated as part of the overall transaction price at contract inception and recognized in earnings ratably over the initial term of the contract with an offset to an accretive contract asset.

Contract Preparation Revenue. Some of our drilling contracts require downtime before the start of the contract to prepare the rig to meet customer requirements. At times, we may be compensated by the customer for such work (on either a fixed lump-sum or variable dayrate basis). These activities are not considered to be distinct within the context of the contract and, therefore, the related revenue is allocated to the overall performance obligation and recognized ratably over the initial term of the related drilling contract. We record a contract liability for contract preparation fees received, which is amortized ratably to contract drilling revenue over the initial term of the related drilling contract.

Bonuses, Penalties and Other Variable Consideration. We may receive bonus increases to revenue or penalty decreases to revenue. Based on historical data and ongoing communication with the operator/customer, we are able to reasonably estimate this variable consideration. We will record such estimated variable consideration and re-measure our estimates at each reporting date. For revenue estimated, but not received, we will record to “Prepaid expenses and other current assets” on our Consolidated Balance Sheets.

Capital Modification Revenue. From time to time, we may receive fees from our customers for capital improvements to our rigs to meet contractual requirements (on either a fixed lump-sum or variable dayrate basis). Such revenue is allocated to the overall performance obligation and recognized ratably over the initial term of the related drilling contract as these activities are integral to our drilling activities and are not considered to be a stand-alone service provided to the customer within the context of our contracts. We record a contract liability for such fees and recognize them ratably as contract drilling revenue over the initial term of the related drilling contract.

Revenues Related to Reimbursable Expenses. We generally receive reimbursements from our customers for the purchase of supplies, equipment, personnel services and other services provided at their request in accordance with a drilling contract or other agreement. Such reimbursable revenue is variable and subject to uncertainty, as the amounts received and timing thereof is highly dependent on factors outside of our influence. Accordingly, reimbursable revenue is constrained revenue and not included in the total transaction price until the uncertainty is resolved, which typically occurs when the related costs are incurred on behalf of a customer. We are generally considered a principal in such transactions and record the associated revenue at the gross amount billed to the customer as “Reimbursables and other” in our Consolidated Statements of Operations. Such amounts are recognized ratably over the period within the contract term during which the corresponding goods and services are to be consumed.

Deferred revenues from drilling contracts totaled $65.1 million and $80.8 million at December 31, 2019 and 2018, 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 $30.8 million at December 31, 2019 as compared to $47.7 million at December 31, 2018 and are included in either “Prepaid expenses and other current assets,” “Other assets” or “Property and equipment, net” in the accompanying Consolidated Balance Sheets, based upon our expected time of recognition.

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.

Deferred tax assets and liabilities are recognized for the anticipated future tax effects of temporary differences between the financial statement basis and the tax basis of our assets and liabilities using the applicable jurisdictional tax rates at year-end. A valuation allowance for deferred tax assets is recorded when it is more likely than not that the deferred tax asset will not be realized in a future period.

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 United States, UK and any other 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 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. The Company has adopted an accounting policy to look through the outside basis of partnerships and all other flow-through entities and exclude these from the computation of deferred taxes.

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 December 31, 2019 and 2018, loss reserves for personal injury and protection claims totaled $27.9 million and $22.4 million, respectively, and such amounts are included in “Other current liabilities” in the accompanying Consolidated Balance Sheets.

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.

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.

We are involved in legal proceedings, claims, and regulatory, tax or government inquiries and investigations that arise in the ordinary course of business. Certain of these matters include speculative claims for substantial or indeterminate amounts of damages. We record a liability when we believe that it is both probable that a loss has been incurred and the amount can be reasonably estimated. If we determine that a loss is reasonably possible and the loss or range of loss can be estimated, we disclose the possible loss in the notes to the consolidated financial statements.

We review the developments in our contingencies that could affect the amount of the provisions that has been previously recorded, and the matters and related possible losses disclosed. We make adjustments to our provisions and changes to our disclosures accordingly to reflect the impact of negotiations, settlements, rulings, advice of legal counsel, and updated information. Significant judgement is required to determine both the probability and the estimated amount.

On August 1, 2014, Noble-UK completed the separation and spin-off of a majority of its standard specification offshore drilling business (the “Spin-off”) through a pro rata distribution of all of the ordinary shares of its wholly-owned subsidiary, Paragon Offshore plc (“Paragon Offshore”), to the holders of Noble’s ordinary shares. Paragon Offshore, which had been reflected as continuing operations in our consolidated financial statements prior to the Spin-off, meets the criteria for being reported as discontinued operations and has been reclassified as such in our results of operations.

Prior to the completion of the Spin-off, Noble-UK and Paragon Offshore entered into a series of agreements to effect the separation and Spin-off and govern the relationship between the parties after the Spin-off (the “Separation Agreements”), including the Master Separation Agreement (the “MSA”) and the Tax Sharing Agreement (the “TSA”). During the year ended December 31, 2017, we recorded a non-cash loss of $1.5 million in “Net loss from discontinued operations, net of tax” on our Consolidated Statement of Operations from the effects of Paragon Offshore's rejection of the Separation Agreements. During the year ended December 31, 2019, we recognized charges of $3.8 million recorded in “Net loss from discontinued operations, net of tax” on our Consolidated Statement of Operations relating to settlement of Mexico customs audits from rigs included in the Spin-off. For additional information related to the Spin-off, refer to “Note 16— Commitments and Contingencies.”

The preparation of financial statements in conformity with 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.

In February 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-02 (Topic 842, “Leases”), as amended, which generally requires lessees to recognize operating and financing lease liabilities and corresponding right-of-use assets on the balance sheet and to provide enhanced disclosures surrounding the amount, time and uncertainty of cash flows arising from lease agreements. We adopted this standard, on a modified retrospective basis, effective January 1, 2019 and did not restate comparative periods. Our adoption did not have a material effect on our consolidated financial statements.

With respect to leases in which we are the lessee, we recognized a lease liability and a corresponding right-of-use asset of approximately $28.0 million on our Consolidated Balance Sheet as of January 1, 2019. We have elected the package of practical expedients that permits us to not reassess (1) whether previously expired or existing contracts are or contain leases, (2) the lease classification for any expired or existing leases, and (3) any initial direct costs for any existing leases as of the effective date. In addition, we have elected the hindsight practical expedient in connection with our adoption of the new lease standard. As lessee, we have made the accounting policy election to not recognize a right-of-use asset lease and lease liability for leases with a term of 12 months or less. We will recognize lease payments in the Consolidated Statements of Operations on a straight-line basis over the lease term. We have also elected the practical expedient to not separate lease and non-lease components.

Our drilling contracts contain a lease component related to the underlying drilling equipment, in addition to the service component provided by our crews and our expertise to operate such drilling equipment. We have concluded the non-lease service of operating our equipment and providing expertise in the drilling of the client’s well is predominant in our drilling contracts. We have applied the practical expedient to account for the lease and associated nonlease components as a single component. With the election of the practical expedient, we will continue to present a single performance obligation under the new revenue guidance in Accounting Standards Codification (“ASC”) Topic 606, “Revenue from Contracts with Customers.”

In December 2019, the FASB issued ASU No. 2019-12, which amends ASC Subtopic 740, “Income Taxes” This update simplifies the accounting for income taxes by removing certain exceptions to general principles. The amendment is effective for fiscal years beginning after December 15, 2020 and is required to be adopted on a retrospective basis for all periods presented. We are evaluating what impact, if any, the adoption of this guidance will have on our consolidated financial statements.

In August 2018, the FASB issued ASU No. 2018-14, which amends ASC Subtopic 715-20, “Compensation — Retirement Benefits — Defined Benefit Plans — General.” This update applies to all employers that sponsor defined benefit pension or other postretirement plans and is part of the disclosure framework project to improve the effectiveness of disclosures in notes to the financial statements. The amendment is effective for fiscal years ending after December 15, 2020 and is required to be adopted on a retrospective basis for all periods presented. We do not expect the adoption of this guidance to materially affect our consolidated financial statements.

In June 2016, the FASB issued ASU No. 2016-13 (Topic 326, “Measurement of Credit Losses on Financial Instruments”), which requires changes to the recognition of credit losses on financial instruments not accounted for at fair value through net income, including loans, debt securities, trade receivables, net investments in leases and available-for-sale debt securities. This guidance will be effective for annual and interim periods beginning after December 15, 2019. Entities are required to apply the standard’s provisions as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. We do not expect the adoption of this guidance to materially affect our consolidated financial statements.