Contingencies	9 Months Ended
Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies Brazil Internal Investigation Pride International LLC, formerly Pride International, Inc. (“Pride”), a company we acquired in 2011, commenced drilling operations in Brazil in 2001. In 2008, Pride entered into a drilling services agreement with Petrobras (the "DSA") for ENSCO DS-5, a drillship ordered from Samsung Heavy Industries, a shipyard in South Korea ("SHI"). Beginning in 2006, Pride conducted periodic compliance reviews of its business with Petrobras, and, after the acquisition of Pride, Ensco conducted similar compliance reviews. We commenced a compliance review in early 2015 after media reports were released regarding ongoing investigations of various kickback and bribery schemes in Brazil involving Petrobras. While conducting our compliance review, we became aware of an internal audit report by Petrobras alleging irregularities in relation to the DSA. Upon learning of the Petrobras internal audit report, our Audit Committee appointed independent counsel to lead an investigation into the alleged irregularities. Further, in June and July 2015, we voluntarily contacted the SEC and the U.S. Department of Justice ("DOJ"), respectively, to advise them of this matter and of our Audit Committee’s investigation. Independent counsel, under the direction of our Audit Committee, has substantially completed its investigation by reviewing and analyzing available documents and correspondence and interviewing current and former employees involved in the DSA negotiations and the negotiation of the ENSCO DS-5 construction contract with SHI (the "DS-5 Construction Contract"). To date, our Audit Committee has found no credible evidence that Pride or Ensco or any of their current or former employees were aware of or involved in any wrongdoing, and our Audit Committee has found no credible evidence linking Ensco or Pride to any illegal acts committed by our former marketing consultant who provided services to Pride and Ensco in connection with the DSA. Independent counsel has continued to provide the SEC and DOJ with updates throughout the investigation, including detailed briefings regarding its investigation and findings. We entered into a one-year tolling agreement with the DOJ that expired in December 2016. We extended our tolling agreement with the SEC for 12 months until March 2018. Subsequent to initiating our Audit Committee investigation, Brazilian court documents connected to the prosecution of former Petrobras directors and employees as well as certain other third parties, including our former marketing consultant, referenced the alleged irregularities cited in the Petrobras internal audit report. Our former marketing consultant has entered into a plea agreement with the Brazilian authorities. On January 10, 2016, Brazilian authorities filed an indictment against a former Petrobras director. This indictment states that the former Petrobras director received bribes paid out of proceeds from a brokerage agreement entered into for purposes of intermediating a drillship construction contract between SHI and Pride, which we believe to be the DS-5 Construction Contract. The parties to the brokerage agreement were a company affiliated with a person acting on behalf of the former Petrobras director, a company affiliated with our former marketing consultant, and SHI. The indictment alleges that amounts paid by SHI under the brokerage agreement ultimately were used to pay bribes to the former Petrobras director. The indictment does not state that Pride or Ensco or any of their current or former employees were involved in the bribery scheme or had any knowledge of the bribery scheme. On January 4, 2016, we received a notice from Petrobras declaring the DSA void effective immediately. Petrobras’ notice alleges that our former marketing consultant both received and procured improper payments from SHI for employees of Petrobras and that Pride had knowledge of this activity and assisted in the procurement of and/or facilitated these improper payments. We disagree with Petrobras’ allegations. See "DSA Dispute" below for additional information. In August 2017, one of our Brazilian subsidiaries was contacted by the Office of the Attorney General for the Brazilian state of Paraná in connection with a criminal investigation procedure initiated against agents of both SHI and Pride in relation to the DSA. The Brazilian authorities requested information regarding our compliance program and the findings of our internal investigations. We are cooperating with the Office of the Attorney General and have provided documents in response to their request. We cannot predict the scope or ultimate outcome of this procedure or whether any other governmental authority will open an investigation into Pride’s involvement in this matter, or if a proceeding were opened, the scope or ultimate outcome of any such investigation. If the SEC or DOJ determines that violations of the FCPA have occurred, or if any governmental authority determines that we have violated applicable anti-bribery laws, they could seek civil and criminal sanctions, including monetary penalties, against us, as well as changes to our business practices and compliance programs, any of which could have a material adverse effect on our business and financial condition. Although our internal investigation is substantially complete, we cannot predict whether any additional allegations will be made or whether any additional facts relevant to the investigation will be uncovered during the course of the investigation and what impact those allegations and additional facts will have on the timing or conclusions of the investigation. Our Audit Committee will examine any such additional allegations and additional facts and the circumstances surrounding them. DSA Dispute As described above, on January 4, 2016, Petrobras sent a notice to us declaring the DSA void effective immediately, reserving its rights and stating its intention to seek any restitution to which it may be entitled. We disagree with Petrobras’ declaration that the DSA is void. We believe that Petrobras repudiated the DSA and have therefore accepted the DSA as terminated on April 8, 2016 (the "Termination Date"). At this time, we cannot reasonably determine the validity of Petrobras' claim or the range of our potential exposure, if any. As a result, there can be no assurance as to how this dispute will ultimately be resolved. We did not recognize revenue for amounts owed to us under the DSA from the beginning of the fourth quarter of 2015 through the Termination Date, as we concluded that collectability of these amounts was not reasonably assured. Additionally, our receivables from Petrobras related to the DSA from prior to the fourth quarter of 2015 are fully reserved in our condensed consolidated balance sheet as of September 30, 2017. We have initiated arbitration proceedings in the U.K. against Petrobras seeking payment of all amounts owed to us under the DSA, in addition to any other amounts to which we are entitled, and intend to vigorously pursue our claims. Petrobras subsequently filed a counterclaim seeking restitution of certain sums paid under the DSA less value received by Petrobras under the DSA. We have also initiated separate arbitration proceedings in the U.K. against SHI for any losses we have incurred in connection with the foregoing. SHI subsequently filed a statement of defense disputing our claim. There can be no assurance as to how these arbitration proceedings will ultimately be resolved. Customer Dispute A customer filed a lawsuit in Texas federal court against one of our subsidiaries claiming damages based on allegations that our subsidiary breached and was negligent in the performance of a drilling contract during the period beginning in mid-2011 through May 2012. The customer's court documents alleged damages totaling approximately $40 million. During the second quarter, we settled the lawsuit and agreed to pay the customer $9.8 million, which was recognized in contract drilling expense in our condensed consolidated statements of operations for the nine-month period ended September 30, 2017. Atwood Merger On June 23, 2017, a putative class action captioned Bernard Stern v. Atwood Oceanics, Inc., et al, was filed in the U.S. District Court for the Southern District of Texas against Atwood, Atwood’s directors, Ensco and Merger Sub. The Stern complaint generally alleges that Atwood and the Atwood directors disseminated a false or misleading registration statement on Form S-4 (the “Registration Statement”) on June 16, 2017, which omitted material information regarding the proposed Merger, in violation of Section 14(a) of the Exchange Act. Specifically, the Stern complaint alleges that Atwood and the Atwood directors omitted material information regarding the parties’ financial projections, the analysis performed by Atwood’s financial advisor, Goldman Sachs & Co. LLC (“Goldman Sachs”), in support of its fairness opinion, the timing and nature of communications regarding post-transaction employment of Atwood's directors and officers, potential conflicts of interest of Goldman Sachs, and whether there were further discussions with another potential acquirer of Atwood following the May 30, 2017 announcement of the Merger. The Stern complaint further alleges that the Atwood directors, Ensco and Merger Sub are liable for these violations as “control persons” of Atwood under Section 20(a) of the Exchange Act. With respect to Ensco, the Stern complaint alleges that Ensco had direct supervisory control over the composition of the Registration Statement. The Stern complaint seeks injunctive relief, including to enjoin the Merger, rescissory damages, and an award of attorneys’ fees in addition to other relief. On June 27, 2017, June 29, 2017 and June 30, 2017, additional putative class actions captioned Joseph Composto v. Atwood Oceanics, Inc., et al, Booth Family Trust v. Atwood Oceanics, Inc., et al and Mary Carter v. Atwood Oceanics, Inc.et al, respectively, were filed in the U.S. District Court for the Southern District of Texas against Atwood and Atwood’s directors. These actions allege violations of Sections 14(a) and 20(a) of the Exchange Act by Atwood and Atwood’s directors similar to those alleged in the Stern complaint; however, neither Ensco plc nor Merger Sub is named as a defendant in these actions. On October 2, 2017, the actions were consolidated and the Stern matter was designated as the lead case. The plaintiffs subsequently voluntarily dismissed the actions. Other Matters In addition to the foregoing, we are named defendants or parties in certain other lawsuits, claims or proceedings incidental to our business and are involved from time to time as parties to governmental investigations or proceedings, including matters related to taxation, arising in the ordinary course of business. Although the outcome of such lawsuits or other proceedings cannot be predicted with certainty and the amount of any liability that could arise with respect to such lawsuits or other proceedings cannot be predicted accurately, we do not expect these matters to have a material adverse effect on our financial position, operating results or cash flows. In the ordinary course of business with customers and others, we have entered into letters of credit and surety bonds to guarantee our performance as it relates to our drilling contracts, contract bidding, customs duties, tax appeals and other obligations in various jurisdictions. Letters of credit and surety bonds outstanding as of September 30, 2017 totaled $83.5 million and were issued under facilities provided by various banks and other financial institutions. Obligations under these letters of credit and surety bonds are not normally called as we typically comply with the underlying performance requirement. As of September 30, 2017, we were not required to make collateral deposits with respect to these agreements.

Contingencies

Brazil Internal Investigation

Pride International LLC, formerly Pride International, Inc. (“Pride”), a company we acquired in 2011, commenced drilling operations in Brazil in 2001. In 2008, Pride entered into a drilling services agreement with Petrobras (the "DSA") for ENSCO DS-5, a drillship ordered from Samsung Heavy Industries, a shipyard in South Korea ("SHI"). Beginning in 2006, Pride conducted periodic compliance reviews of its business with Petrobras, and, after the acquisition of Pride, Ensco conducted similar compliance reviews.

We commenced a compliance review in early 2015 after media reports were released regarding ongoing investigations of various kickback and bribery schemes in Brazil involving Petrobras. While conducting our compliance review, we became aware of an internal audit report by Petrobras alleging irregularities in relation to the DSA. Upon learning of the Petrobras internal audit report, our Audit Committee appointed independent counsel to lead an investigation into the alleged irregularities. Further, in June and July 2015, we voluntarily contacted the SEC and the U.S. Department of Justice ("DOJ"), respectively, to advise them of this matter and of our Audit Committee’s investigation. Independent counsel, under the direction of our Audit Committee, has substantially completed its investigation by reviewing and analyzing available documents and correspondence and interviewing current and former employees involved in the DSA negotiations and the negotiation of the ENSCO DS-5 construction contract with SHI (the "DS-5 Construction Contract").

To date, our Audit Committee has found no credible evidence that Pride or Ensco or any of their current or former employees were aware of or involved in any wrongdoing, and our Audit Committee has found no credible evidence linking Ensco or Pride to any illegal acts committed by our former marketing consultant who provided services to Pride and Ensco in connection with the DSA. Independent counsel has continued to provide the SEC and DOJ with updates throughout the investigation, including detailed briefings regarding its investigation and findings. We entered into a one-year tolling agreement with the DOJ that expired in December 2016. We extended our tolling agreement with the SEC for 12 months until March 2018.

Subsequent to initiating our Audit Committee investigation, Brazilian court documents connected to the prosecution of former Petrobras directors and employees as well as certain other third parties, including our former marketing consultant, referenced the alleged irregularities cited in the Petrobras internal audit report. Our former marketing consultant has entered into a plea agreement with the Brazilian authorities. On January 10, 2016, Brazilian authorities filed an indictment against a former Petrobras director. This indictment states that the former Petrobras director received bribes paid out of proceeds from a brokerage agreement entered into for purposes of intermediating a drillship construction contract between SHI and Pride, which we believe to be the DS-5 Construction Contract. The parties to the brokerage agreement were a company affiliated with a person acting on behalf of the former Petrobras director, a company affiliated with our former marketing consultant, and SHI. The indictment alleges that amounts paid by SHI under the brokerage agreement ultimately were used to pay bribes to the former Petrobras director. The indictment does not state that Pride or Ensco or any of their current or former employees were involved in the bribery scheme or had any knowledge of the bribery scheme.

On January 4, 2016, we received a notice from Petrobras declaring the DSA void effective immediately. Petrobras’ notice alleges that our former marketing consultant both received and procured improper payments from SHI for employees of Petrobras and that Pride had knowledge of this activity and assisted in the procurement of and/or facilitated these improper payments. We disagree with Petrobras’ allegations. See "DSA Dispute" below for additional information.

In August 2017, one of our Brazilian subsidiaries was contacted by the Office of the Attorney General for the Brazilian state of Paraná in connection with a criminal investigation procedure initiated against agents of both SHI and Pride in relation to the DSA. The Brazilian authorities requested information regarding our compliance program and the findings of our internal investigations. We are cooperating with the Office of the Attorney General and have provided documents in response to their request. We cannot predict the scope or ultimate outcome of this procedure or whether any other governmental authority will open an investigation into Pride’s involvement in this matter, or if a proceeding were opened, the scope or ultimate outcome of any such investigation. If the SEC or DOJ determines that violations of the FCPA have occurred, or if any governmental authority determines that we have violated applicable anti-bribery laws, they could seek civil and criminal sanctions, including monetary penalties, against us, as well as changes to our business practices and compliance programs, any of which could have a material adverse effect on our business and financial condition. Although our internal investigation is substantially complete, we cannot predict whether any additional allegations will be made or whether any additional facts relevant to the investigation will be uncovered during the course of the investigation and what impact those allegations and additional facts will have on the timing or conclusions of the investigation. Our Audit Committee will examine any such additional allegations and additional facts and the circumstances surrounding them.

DSA Dispute

As described above, on January 4, 2016, Petrobras sent a notice to us declaring the DSA void effective immediately, reserving its rights and stating its intention to seek any restitution to which it may be entitled. We disagree with Petrobras’ declaration that the DSA is void. We believe that Petrobras repudiated the DSA and have therefore accepted the DSA as terminated on April 8, 2016 (the "Termination Date"). At this time, we cannot reasonably determine the validity of Petrobras' claim or the range of our potential exposure, if any. As a result, there can be no assurance as to how this dispute will ultimately be resolved.

We did not recognize revenue for amounts owed to us under the DSA from the beginning of the fourth quarter of 2015 through the Termination Date, as we concluded that collectability of these amounts was not reasonably assured. Additionally, our receivables from Petrobras related to the DSA from prior to the fourth quarter of 2015 are fully reserved in our condensed consolidated balance sheet as of September 30, 2017. We have initiated arbitration proceedings in the U.K. against Petrobras seeking payment of all amounts owed to us under the DSA, in addition to any other amounts to which we are entitled, and intend to vigorously pursue our claims. Petrobras subsequently filed a counterclaim seeking restitution of certain sums paid under the DSA less value received by Petrobras under the DSA. We have also initiated separate arbitration proceedings in the U.K. against SHI for any losses we have incurred in connection with the foregoing. SHI subsequently filed a statement of defense disputing our claim. There can be no assurance as to how these arbitration proceedings will ultimately be resolved.

Customer Dispute

A customer filed a lawsuit in Texas federal court against one of our subsidiaries claiming damages based on allegations that our subsidiary breached and was negligent in the performance of a drilling contract during the period beginning in mid-2011 through May 2012. The customer's court documents alleged damages totaling approximately $40 million. During the second quarter, we settled the lawsuit and agreed to pay the customer $9.8 million, which was recognized in contract drilling expense in our condensed consolidated statements of operations for the nine-month period ended September 30, 2017.

Atwood Merger

On June 23, 2017, a putative class action captioned Bernard Stern v. Atwood Oceanics, Inc., et al, was filed in the U.S. District Court for the Southern District of Texas against Atwood, Atwood’s directors, Ensco and Merger Sub. The Stern complaint generally alleges that Atwood and the Atwood directors disseminated a false or misleading registration statement on Form S-4 (the “Registration Statement”) on June 16, 2017, which omitted material information regarding the proposed Merger, in violation of Section 14(a) of the Exchange Act. Specifically, the Stern complaint alleges that Atwood and the Atwood directors omitted material information regarding the parties’ financial projections, the analysis performed by Atwood’s financial advisor, Goldman Sachs & Co. LLC (“Goldman Sachs”), in support of its fairness opinion, the timing and nature of communications regarding post-transaction employment of Atwood's directors and officers, potential conflicts of interest of Goldman Sachs, and whether there were further discussions with another potential acquirer of Atwood following the May 30, 2017 announcement of the Merger. The Stern complaint further alleges that the Atwood directors, Ensco and Merger Sub are liable for these violations as “control persons” of Atwood under Section 20(a) of the Exchange Act. With respect to Ensco, the Stern complaint alleges that Ensco had direct supervisory control over the composition of the Registration Statement. The Stern complaint seeks injunctive relief, including to enjoin the Merger, rescissory damages, and an award of attorneys’ fees in addition to other relief.

On June 27, 2017, June 29, 2017 and June 30, 2017, additional putative class actions captioned Joseph Composto v. Atwood Oceanics, Inc., et al, Booth Family Trust v. Atwood Oceanics, Inc., et al and Mary Carter v. Atwood Oceanics, Inc.et al, respectively, were filed in the U.S. District Court for the Southern District of Texas against Atwood and Atwood’s directors. These actions allege violations of Sections 14(a) and 20(a) of the Exchange Act by Atwood and Atwood’s directors similar to those alleged in the Stern complaint; however, neither Ensco plc nor Merger Sub is named as a defendant in these actions. On October 2, 2017, the actions were consolidated and the Stern matter was designated as the lead case. The plaintiffs subsequently voluntarily dismissed the actions.

Other Matters

In addition to the foregoing, we are named defendants or parties in certain other lawsuits, claims or proceedings incidental to our business and are involved from time to time as parties to governmental investigations or proceedings, including matters related to taxation, arising in the ordinary course of business. Although the outcome of such lawsuits or other proceedings cannot be predicted with certainty and the amount of any liability that could arise with respect to such lawsuits or other proceedings cannot be predicted accurately, we do not expect these matters to have a material adverse effect on our financial position, operating results or cash flows.

In the ordinary course of business with customers and others, we have entered into letters of credit and surety bonds to guarantee our performance as it relates to our drilling contracts, contract bidding, customs duties, tax appeals and other obligations in various jurisdictions. Letters of credit and surety bonds outstanding as of September 30, 2017 totaled $83.5 million and were issued under facilities provided by various banks and other financial institutions. Obligations under these letters of credit and surety bonds are not normally called as we typically comply with the underlying performance requirement. As of September 30, 2017, we were not required to make collateral deposits with respect to these agreements.