Commitments and Contingencies	9 Months Ended
Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 12— Commitments and Contingencies Transocean Ltd. In January 2017, a subsidiary of Transocean Ltd. (“Transocean”) filed suit against us and certain of our subsidiaries for patent infringement in a Texas federal court. The suit claims that five of our newbuild rigs that operated in the U.S. Gulf of Mexico violated Transocean patents relating to what is generally referred to as dual-activity drilling. We were aware of the patents when we constructed the rigs, and we do not believe that our rigs infringe the Transocean patents, which are now expired. The lawsuit is proceeding and we intend to defend ourselves vigorously against this claim. Department of Justice settlement. In December 2014, one of our subsidiaries reached a settlement with the U.S. Department of Justice (“DOJ”) regarding our former drillship, the Noble Discoverer, and the Kulluk, a rig we were providing contract labor services for, in respect of violations of applicable law discovered in connection with a 2012 Coast Guard inspection in Alaska and our own subsequent internal investigation. Under the terms of the agreement, the subsidiary pled guilty to oil record book, ballast record and required hazardous condition reporting violations with respect to the Noble Discoverer and an oil record book violation with respect to the Kulluk. The subsidiary paid $8.2 million in fines and $4.0 million in community service payments and was placed on probation for four years, provided that we may petition the court for early dismissal of probation after three years. If, during the term of probation, the subsidiary fails to adhere to the terms of the plea agreement, the DOJ may withdraw from the plea agreement and would be free to prosecute the subsidiary on all charges arising out of its investigation, including any charges dismissed pursuant to the terms of the plea agreement, as well as potentially other charges. We also implemented a comprehensive environmental compliance plan in connection with the settlement. Brazil commercial agent. We have used a commercial agent in Brazil in connection with our Petróleo Brasileiro S.A. (“Petrobras”) drilling contracts. We understand that this agent has represented a number of different companies in Brazil over many years, including several offshore drilling contractors. In November 2015, this agent pled guilty in Brazil in connection with the award of a drilling contract to a competitor and implicated a Petrobras official as part of a wider investigation of Petrobras’ business practices. Following news reports relating to the agent’s involvement in the Brazil investigation in connection with his activities with other companies, we conducted a review, which is now substantially complete, of our relationship with the agent and with Petrobras. We have been in contact with the SEC, the Brazilian federal prosecutor’s office and the DOJ about this matter. We have cooperated with these agencies and they are aware of our internal review. To our knowledge, neither the agent, nor the government authorities investigating the matter, has alleged that the agent or Noble acted improperly in connection with our contracts with Petrobras. Paragon Offshore. 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, to the holders of Noble’s ordinary shares. In February 2016, Paragon Offshore sought approval of a pre-negotiated plan of reorganization (the "Prior Plan") by filing for voluntary relief under Chapter 11 of the United States Bankruptcy Code. As part of the Prior Plan, we entered into a settlement agreement with Paragon Offshore (the "Settlement Agreement") under which, in exchange for a full and unconditional release of any claims by Paragon Offshore in connection with the Spin-off (including fraudulent conveyance claims that could be brought on behalf of Paragon Offshore’s creditors), we agreed to provide certain tax bonding in Mexico as well as assume certain tax liabilities and the administration of Mexican tax claims for specified years. The bonding to be provided by Noble-UK was a key benefit to Paragon Offshore of the Settlement Agreement, which was subject to bankruptcy court confirmation as part of a bankruptcy plan. The Prior Plan was rejected by the bankruptcy court in October 2016. In April 2017, Paragon Offshore filed an updated disclosure statement and a revised plan of reorganization (the "New Plan") in its bankruptcy proceeding. Under the New Plan, including Paragon Offshore’s revised business plan, Paragon Offshore no longer needed the Mexican tax bonding that Noble-UK was to provide under the Settlement Agreement. As a result, the Settlement Agreement was no longer applicable to the ongoing business of Paragon Offshore. Consequently, Paragon Offshore abandoned the Settlement Agreement as part of the New Plan, and the Settlement Agreement was terminated at the time of the filing of the New Plan. On May 2, 2017, Paragon Offshore announced that it had reached an agreement in principle with both its secured and unsecured creditors to revise the New Plan to, among other things, create and fund a $10.0 million litigation trust to pursue litigation against us. On June 7, 2017, the revised New Plan was approved by the bankruptcy court and Paragon Offshore emerged from bankruptcy on July 18, 2017. We expect Paragon Offshore or its creditors will use the litigation trust to pursue claims against us relating to the Spin-off, including alleged fraudulent conveyance claims. We continue to believe that Paragon Offshore, at the time of the Spin-off, was properly funded, solvent and had appropriate liquidity and that any fraudulent conveyance claim or other claim related to the Spin-off that may be brought by Paragon Offshore or its creditors, would be without merit and would be contested vigorously by us. If litigation is instituted against Noble and we are unsuccessful in defending such claims, it could have a material adverse effect on our financial position, results of operations and/or cash flows. Prior to the completion of the Spin-off, Noble-UK and Paragon Offshore entered into the Separation Agreements to effect the separation and Spin-off and govern the relationship between the parties after the Spin-off, including the MSA and TSA. As part of its final bankruptcy plan, Paragon Offshore rejected the Separation Agreements. Accordingly, the indemnity obligations that Paragon Offshore potentially would have owed us under the Separation Agreements have now terminated, including indemnities arising under the MSA and the TSA in respect of obligations related to Paragon Offshore’s business that were incurred through Noble-retained entities prior to the Spin-off. Likewise, any potential indemnity obligations that we would have owed Paragon Offshore under the Separation Agreements, including those under the MSA and the TSA in respect of Noble-UK’s business that was conducted prior to the Spin-off through Paragon Offshore-retained entities, are now also extinguished. In the absence of the Separation Agreements, liabilities relating to the respective parties will be borne by the owner of the legal entity or asset at issue and neither party will look to an allocation based on the historic relationship of an entity or asset to one of the party’s business, as had been the case under the Separation Agreements. The rejection and ultimate termination of the indemnity and related obligations under the Separation Agreements has resulted in a number of accounting charges and benefits for the nine months ended September 30, 2017, and such termination may continue to affect us in the future as liabilities arise for which we would have been indemnified by Paragon Offshore or would have had to indemnify Paragon Offshore. We do not expect that, overall, the rejection of the Separation Agreements by Paragon Offshore will have a material adverse effect on our financial condition or liquidity. However, any loss we experience with respect to which we would have been able to secure indemnification from Paragon Offshore under one or more of the Separation Agreements could have an adverse impact on our results of operations in any period, which impact may be material depending on our results of operations during this down-cycle. During the nine months ended September 30, 2017, we recognized net charges of $15.9 million, with a non-cash loss of $1.5 million recorded in "Net loss from discontinued operations, net of tax" on our Condensed Consolidated Statement of Operations relating to the emergence from bankruptcy of Paragon Offshore. For more information on the Separation Agreements, see our Annual Report on Form 10-K for the year ended December 31, 2016. Tax matters. During 2014, the IRS began its examination of our tax reporting in the U.S. for the taxable years ended December 31, 2010 and 2011. The IRS examination team has completed its examination of our 2010 and 2011 U.S. tax returns and proposed adjustments and deficiencies with respect to certain items that were reported by us for the 2010 and 2011 tax year. On December 19, 2016, we received the Revenue Agent Report ("RAR") from the IRS. We believe that we have accurately reported all amounts in our tax returns, and have submitted administrative protests with the IRS Office of Appeals contesting the examination team’s proposed adjustments. We intend to vigorously defend our reported positions, and believe the ultimate resolution of the adjustments proposed by the IRS examination team will not have a material adverse effect on our condensed consolidated financial statements. During the third quarter of 2017, the IRS initiated its examination of our 2012, 2013, 2014 and 2015 tax returns. In previous periods, we reported that Mexican and Brazilian authorities had made significant tax assessments against Paragon Offshore entities, a portion of which related to Noble’s business that operated through Paragon Offshore-retained entities in Mexico and Brazil prior to the spin-off. As a result of the termination of the Separation Agreements, we no longer have any indemnity obligations in respect of these tax claims made against Paragon Offshore entities, and responsibility for these claims has reverted back to the applicable Paragon Offshore entity. Audit claims of approximately $51.4 million attributable to income and other business taxes have been assessed against Noble entities in Mexico. In previous periods, we also reported that Petrobras had notified us that it was challenging assessments by Brazilian tax authorities of withholding taxes associated with the provision of drilling rigs for its operations in Brazil during 2008 and 2009. Petrobras had also notified us that if Petrobras was ultimately forced to pay such withholding taxes, it would seek reimbursement from Paragon Offshore who would then seek reimbursement from us for the portion of the withholding that was allocable to our drilling rigs. As a result of the termination of the Separation Agreements, we no longer have any indemnity obligation in respect of these withholding claims made against a Paragon Offshore entity, and responsibility for these claims has reverted back to the applicable Paragon Offshore entity. We operate in a number of countries throughout the world and our tax returns filed in those jurisdictions are subject to review and examination by tax authorities within those jurisdictions. We recognize uncertain tax positions that we believe have a greater than 50 percent likelihood of being sustained. We cannot predict or provide assurance as to the ultimate outcome of any existing or future assessments. Other legal matters. We maintain certain insurance coverage against specified marine perils, which includes physical damage and loss of hire to our drilling rigs along with other associated coverage common in our industry. We maintain a physical damage deductible on our rigs of $25.0 million per occurrence. With respect to the U.S. Gulf of Mexico, hurricane risk has generally resulted in more restrictive and expensive coverage for U.S. named windstorm perils, and we have opted in certain years to maintain limited or no windstorm coverage. Our current program provides for $500.0 million in named windstorm coverage in the U.S. Gulf of Mexico. The loss of hire coverage applies only to our rigs operating under contract with a dayrate equal to or greater than $200,000 a day and is subject to a 45-day waiting period for each unit and each occurrence. Although we maintain insurance in the geographic areas in which we operate, pollution, reservoir damage and environmental risks generally are not fully insurable. Our insurance policies and contractual rights to indemnity may not adequately cover our losses or may have exclusions of coverage for some losses. We do not have insurance coverage or rights to indemnity for all risks, including loss of hire insurance on most of the rigs in our fleet. Uninsured exposures may include expatriate activities prohibited by U.S. laws and regulations, radiation hazards, certain loss or damage to property on board our rigs and losses relating to shore-based terrorist acts, strikes or cyber risks. If a significant accident or other event occurs and is not fully covered by insurance or contractual indemnity, it could materially adversely affect our financial position, results of operations or cash flows. Additionally, there can be no assurance that those parties with contractual obligations to indemnify us will necessarily be financially able to indemnify us against all these risks. We carry protection and indemnity insurance covering marine third party liability exposures, which also includes coverage for employer’s liability resulting from personal injury to our offshore drilling crews. Our protection and indemnity policy currently has a standard deductible of $10.0 million per occurrence, with maximum liability coverage of $750.0 million. We have entered into agreements with certain of our executive officers, as well as certain other employees. These agreements become effective upon a change of control of Noble-UK (within the meaning set forth in the agreements) or a termination of employment in connection with or in anticipation of a change of control, and remain effective for three years thereafter. These agreements provide for compensation and certain other benefits under such circumstances. We are a defendant in certain claims and litigation arising out of operations in the ordinary course of business, including personal injury claims, the resolution of which, in the opinion of management, will not be material to our financial position, results of operations or cash flows. There is inherent risk in any litigation or dispute and no assurance can be given as to the outcome of these claims.

Note 12— Commitments and Contingencies

Transocean Ltd. In January 2017, a subsidiary of Transocean Ltd. (“Transocean”) filed suit against us and certain of our subsidiaries for patent infringement in a Texas federal court. The suit claims that five of our newbuild rigs that operated in the U.S. Gulf of Mexico violated Transocean patents relating to what is generally referred to as dual-activity drilling. We were aware of the patents when we constructed the rigs, and we do not believe that our rigs infringe the Transocean patents, which are now expired. The lawsuit is proceeding and we intend to defend ourselves vigorously against this claim.

Department of Justice settlement. In December 2014, one of our subsidiaries reached a settlement with the U.S. Department of Justice (“DOJ”) regarding our former drillship, the Noble Discoverer, and the Kulluk, a rig we were providing contract labor services for, in respect of violations of applicable law discovered in connection with a 2012 Coast Guard inspection in Alaska and our own subsequent internal investigation. Under the terms of the agreement, the subsidiary pled guilty to oil record book, ballast record and required hazardous condition reporting violations with respect to the Noble Discoverer and an oil record book violation with respect to the Kulluk. The subsidiary paid $8.2 million in fines and $4.0 million in community service payments and was placed on probation for four years, provided that we may petition the court for early dismissal of probation after three years. If, during the term of probation, the subsidiary fails to adhere to the terms of the plea agreement, the DOJ may withdraw from the plea agreement and would be free to prosecute the subsidiary on all charges arising out of its investigation, including any charges dismissed pursuant to the terms of the plea agreement, as well as potentially other charges. We also implemented a comprehensive environmental compliance plan in connection with the settlement.

Brazil commercial agent. We have used a commercial agent in Brazil in connection with our Petróleo Brasileiro S.A. (“Petrobras”) drilling contracts. We understand that this agent has represented a number of different companies in Brazil over many years, including several offshore drilling contractors. In November 2015, this agent pled guilty in Brazil in connection with the award of a drilling contract to a competitor and implicated a Petrobras official as part of a wider investigation of Petrobras’ business practices. Following news reports relating to the agent’s involvement in the Brazil investigation in connection with his activities with other companies, we conducted a review, which is now substantially complete, of our relationship with the agent and with Petrobras. We have been in contact with the SEC, the Brazilian federal prosecutor’s office and the DOJ about this matter. We have cooperated with these agencies and they are aware of our internal review. To our knowledge, neither the agent, nor the government authorities investigating the matter, has alleged that the agent or Noble acted improperly in connection with our contracts with Petrobras.

Paragon Offshore. 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, to the holders of Noble’s ordinary shares. In February 2016, Paragon Offshore sought approval of a pre-negotiated plan of reorganization (the "Prior Plan") by filing for voluntary relief under Chapter 11 of the United States Bankruptcy Code. As part of the Prior Plan, we entered into a settlement agreement with Paragon Offshore (the "Settlement Agreement") under which, in exchange for a full and unconditional release of any claims by Paragon Offshore in connection with the Spin-off (including fraudulent conveyance claims that could be brought on behalf of Paragon Offshore’s creditors), we agreed to provide certain tax bonding in Mexico as well as assume certain tax liabilities and the administration of Mexican tax claims for specified years. The bonding to be provided by Noble-UK was a key benefit to Paragon Offshore of the Settlement Agreement, which was subject to bankruptcy court confirmation as part of a bankruptcy plan. The Prior Plan was rejected by the bankruptcy court in October 2016.

In April 2017, Paragon Offshore filed an updated disclosure statement and a revised plan of reorganization (the "New Plan") in its bankruptcy proceeding. Under the New Plan, including Paragon Offshore’s revised business plan, Paragon Offshore no longer needed the Mexican tax bonding that Noble-UK was to provide under the Settlement Agreement. As a result, the Settlement Agreement was no longer applicable to the ongoing business of Paragon Offshore. Consequently, Paragon Offshore abandoned the Settlement Agreement as part of the New Plan, and the Settlement Agreement was terminated at the time of the filing of the New Plan. On May 2, 2017, Paragon Offshore announced that it had reached an agreement in principle with both its secured and unsecured creditors to revise the New Plan to, among other things, create and fund a $10.0 million litigation trust to pursue litigation against us. On June 7, 2017, the revised New Plan was approved by the bankruptcy court and Paragon Offshore emerged from bankruptcy on July 18, 2017.

We expect Paragon Offshore or its creditors will use the litigation trust to pursue claims against us relating to the Spin-off, including alleged fraudulent conveyance claims. We continue to believe that Paragon Offshore, at the time of the Spin-off, was properly funded, solvent and had appropriate liquidity and that any fraudulent conveyance claim or other claim related to the Spin-off that may be brought by Paragon Offshore or its creditors, would be without merit and would be contested vigorously by us. If litigation is instituted against Noble and we are unsuccessful in defending such claims, it could have a material adverse effect on our financial position, results of operations and/or cash flows.

Prior to the completion of the Spin-off, Noble-UK and Paragon Offshore entered into the Separation Agreements to effect the separation and Spin-off and govern the relationship between the parties after the Spin-off, including the MSA and TSA.

As part of its final bankruptcy plan, Paragon Offshore rejected the Separation Agreements. Accordingly, the indemnity obligations that Paragon Offshore potentially would have owed us under the Separation Agreements have now terminated, including indemnities arising under the MSA and the TSA in respect of obligations related to Paragon Offshore’s business that were incurred through Noble-retained entities prior to the Spin-off. Likewise, any potential indemnity obligations that we would have owed Paragon Offshore under the Separation Agreements, including those under the MSA and the TSA in respect of Noble-UK’s business that was conducted prior to the Spin-off through Paragon Offshore-retained entities, are now also extinguished. In the absence of the Separation Agreements, liabilities relating to the respective parties will be borne by the owner of the legal entity or asset at issue and neither party will look to an allocation based on the historic relationship of an entity or asset to one of the party’s business, as had been the case under the Separation Agreements.

The rejection and ultimate termination of the indemnity and related obligations under the Separation Agreements has resulted in a number of accounting charges and benefits for the nine months ended September 30, 2017, and such termination may continue to affect us in the future as liabilities arise for which we would have been indemnified by Paragon Offshore or would have had to indemnify Paragon Offshore. We do not expect that, overall, the rejection of the Separation Agreements by Paragon Offshore will have a material adverse effect on our financial condition or liquidity. However, any loss we experience with respect to which we would have been able to secure indemnification from Paragon Offshore under one or more of the Separation Agreements could have an adverse impact on our results of operations in any period, which impact may be material depending on our results of operations during this down-cycle.

During the nine months ended September 30, 2017, we recognized net charges of $15.9 million, with a non-cash loss of $1.5 million recorded in "Net loss from discontinued operations, net of tax" on our Condensed Consolidated Statement of Operations relating to the emergence from bankruptcy of Paragon Offshore.

For more information on the Separation Agreements, see our Annual Report on Form 10-K for the year ended December 31, 2016.

Tax matters. During 2014, the IRS began its examination of our tax reporting in the U.S. for the taxable years ended December 31, 2010 and 2011. The IRS examination team has completed its examination of our 2010 and 2011 U.S. tax returns and proposed adjustments and deficiencies with respect to certain items that were reported by us for the 2010 and 2011 tax year. On December 19, 2016, we received the Revenue Agent Report ("RAR") from the IRS. We believe that we have accurately reported all amounts in our tax returns, and have submitted administrative protests with the IRS Office of Appeals contesting the examination team’s proposed adjustments. We intend to vigorously defend our reported positions, and believe the ultimate resolution of the adjustments proposed by the IRS examination team will not have a material adverse effect on our condensed consolidated financial statements. During the third quarter of 2017, the IRS initiated its examination of our 2012, 2013, 2014 and 2015 tax returns.

In previous periods, we reported that Mexican and Brazilian authorities had made significant tax assessments against Paragon Offshore entities, a portion of which related to Noble’s business that operated through Paragon Offshore-retained entities in Mexico and Brazil prior to the spin-off. As a result of the termination of the Separation Agreements, we no longer have any indemnity obligations in respect of these tax claims made against Paragon Offshore entities, and responsibility for these claims has reverted back to the applicable Paragon Offshore entity. Audit claims of approximately $51.4 million attributable to income and other business taxes have been assessed against Noble entities in Mexico.

In previous periods, we also reported that Petrobras had notified us that it was challenging assessments by Brazilian tax authorities of withholding taxes associated with the provision of drilling rigs for its operations in Brazil during 2008 and 2009. Petrobras had also notified us that if Petrobras was ultimately forced to pay such withholding taxes, it would seek reimbursement from Paragon Offshore who would then seek reimbursement from us for the portion of the withholding that was allocable to our drilling rigs. As a result of the termination of the Separation Agreements, we no longer have any indemnity obligation in respect of these withholding claims made against a Paragon Offshore entity, and responsibility for these claims has reverted back to the applicable Paragon Offshore entity.

We operate in a number of countries throughout the world and our tax returns filed in those jurisdictions are subject to review and examination by tax authorities within those jurisdictions. We recognize uncertain tax positions that we believe have a greater than 50 percent likelihood of being sustained. We cannot predict or provide assurance as to the ultimate outcome of any existing or future assessments.

Other legal matters. We maintain certain insurance coverage against specified marine perils, which includes physical damage and loss of hire to our drilling rigs along with other associated coverage common in our industry. We maintain a physical damage deductible on our rigs of $25.0 million per occurrence. With respect to the U.S. Gulf of Mexico, hurricane risk has generally resulted in more restrictive and expensive coverage for U.S. named windstorm perils, and we have opted in certain years to maintain limited or no windstorm coverage. Our current program provides for $500.0 million in named windstorm coverage in the U.S. Gulf of Mexico. The loss of hire coverage applies only to our rigs operating under contract with a dayrate equal to or greater than $200,000 a day and is subject to a 45-day waiting period for each unit and each occurrence.

Although we maintain insurance in the geographic areas in which we operate, pollution, reservoir damage and environmental risks generally are not fully insurable. Our insurance policies and contractual rights to indemnity may not adequately cover our losses or may have exclusions of coverage for some losses. We do not have insurance coverage or rights to indemnity for all risks, including loss of hire insurance on most of the rigs in our fleet. Uninsured exposures may include expatriate activities prohibited by U.S. laws and regulations, radiation hazards, certain loss or damage to property on board our rigs and losses relating to shore-based terrorist acts, strikes or cyber risks. If a significant accident or other event occurs and is not fully covered by insurance or contractual indemnity, it could materially adversely affect our financial position, results of operations or cash flows. Additionally, there can be no assurance that those parties with contractual obligations to indemnify us will necessarily be financially able to indemnify us against all these risks.

We carry protection and indemnity insurance covering marine third party liability exposures, which also includes coverage for employer’s liability resulting from personal injury to our offshore drilling crews. Our protection and indemnity policy currently has a standard deductible of $10.0 million per occurrence, with maximum liability coverage of $750.0 million.

We have entered into agreements with certain of our executive officers, as well as certain other employees. These agreements become effective upon a change of control of Noble-UK (within the meaning set forth in the agreements) or a termination of employment in connection with or in anticipation of a change of control, and remain effective for three years thereafter. These agreements provide for compensation and certain other benefits under such circumstances.

We are a defendant in certain claims and litigation arising out of operations in the ordinary course of business, including personal injury claims, the resolution of which, in the opinion of management, will not be material to our financial position, results of operations or cash flows. There is inherent risk in any litigation or dispute and no assurance can be given as to the outcome of these claims.