Litigation	9 Months Ended
Sep. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
Litigation	14. Litigation On March 10, 2015, a purported class action lawsuit was filed against the Company and certain of the Company’s officers in the United States District Court for the Southern District of California, captioned Colley v. Orexigen, et al. The following day, two additional putative class action lawsuits were filed in the same court, captioned Stefanko v. Orexigen, et al., and Yantz v. Orexigen, et al., asserting substantially similar claims. On June 22, 2015, the court consolidated the lawsuits and appointed a lead plaintiff. On August 20, 2015, the lead plaintiff filed a consolidated complaint. The consolidated complaint purports to assert claims on behalf of a class of purchasers of the Company’s stock between March 3, 2015 and May 12, 2015. It alleges that defendants violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 by purportedly making false and misleading statements regarding the interim results and termination of the Light Study. The consolidated complaint seeks an unspecified amount of damages, attorneys’ fees and equitable or injunctive relief. On October 5, 2015, defendants filed a motion to dismiss the consolidated complaint. On May 19, 2016, the District Court granted the motion to dismiss, dismissing portions of the consolidated complaint with prejudice and portions without prejudice. The Court granted the lead plaintiff 30 days to file an amended complaint with respect to those portions not dismissed with prejudice. On June 16, 2016, the lead plaintiff filed a notice of intent not to file an amended complaint but to proceed directly to an appeal of the Court’s decision dismissing the consolidated complaint. As a result, the court entered judgment dismissing the consolidated complaint with prejudice on June 27, 2016. The lead plaintiff filed a Notice of Appeal with the Ninth Circuit Court of Appeals on July 26, 2016. On November 6, 2017, the Ninth Circuit held oral arguments on the appeal but has not yet issued its decision. Although management believes that this appeal lacks merit and intends to defend against it vigorously, there are uncertainties inherent in any litigation and the Company cannot predict the outcome. At this time, the Company is unable to estimate possible losses or ranges of losses that may result from such legal proceedings, and it has not accrued any amounts in connection with such legal proceedings other than ongoing attorney’s fees. On June 3, 2016, plaintiff Ben Wilkin, a shareholder who had previously made a shareholder demand to inspect certain books and records of the Company, filed a derivative lawsuit purportedly on behalf of the Company against certain of the Company’s current and former officers and members of the board of directors in the Delaware Chancery Court, captioned Wilkin v. Narachi, et al. The lawsuit asserts claims for breach of fiduciary duty and waste of corporate assets based on essentially the same set of facts underlying the Colley, Stefanko and Yantz consolidated class action. The lawsuit seeks, among other things, damages, corporate governance reforms, injunctive relief, restitution, disgorgement and attorney’s fees. Orexigen and the individual defendants filed a motion to dismiss on October 31, 2016, asserting that plaintiff failed to plead demand futility and otherwise failed to state a claim. Instead of opposing the motion to dismiss, on January 13, 2017, plaintiff filed an amended complaint pursuant to Chancery Rule 15(aaa). The amended complaint asserts nearly identical allegations and claims as the original complaint. Orexigen and the individual defendants filed a motion to dismiss on March 27, 2017. A hearing on Orexigen’s and the individual defendants’ motion to dismiss is scheduled for November 17, 2017. Management believes that the claims lack merit and intends to defend against them vigorously. The Company is unable to estimate possible losses or ranges of losses that may result from this lawsuit and has not accrued any amounts in connection with this suit. It is possible that additional securities class action litigation may be brought against the Company following stock price declines related to the release of information regarding Contrave or clinical trial results, including the Light Study. Any adverse determination in such litigation could subject the Company to significant liabilities. In April 2015, the Company and Takeda received a Paragraph IV certification notice letter regarding an abbreviated new drug application, or ANDA, submitted to the FDA by Actavis Laboratories FL, Inc., or Actavis, requesting approval to market, sell, and use a generic version of Contrave. In its notice letter, Actavis alleged that U.S. Patent Nos. 7,375,111, 7,462,626, 8,088,786, 8,318,788, 8,722,085, 8,815,889, and 8,916,195, which are listed in the FDA’s Approved Drug Products with Therapeutic Equivalence Evaluations, or the Orange Book, for Contrave, are invalid, unenforceable and/or would not be infringed by Actavis’ manufacture, use or sale of the product described in its ANDA. In June 2015, the Company and Takeda filed a patent infringement lawsuit in the U.S. District Court for the District of Delaware against Actavis and certain of its affiliates related to the ANDA previously filed by Actavis and described above. The lawsuit claims infringement of the seven patents that were the subject of Actavis’ notice letter, as described above. In accordance with the Drug Price Competition and Patent Term Restoration Act of 1984, known as the Hatch-Waxman Act, as a result of having filed a patent infringement lawsuit within 45 days of receipt of Actavis’ notice letter, FDA approval of the ANDA was stayed until the earlier of (i) 30 months from the date of receipt of the notice letter or (ii) a District Court decision finding that the identified patents were invalid, unenforceable or not infringed. In July 2015, Actavis filed an answer, affirmative defenses and counterclaim to the Company’s and Takeda’s complaint, and the Company and Takeda filed an answer to Actavis’ counterclaim in August 2015. Moreover, in July 2015, the court ordered a stipulation between the Company, Takeda and Actavis in which Orexigen and Takeda agreed to dismiss all defendants except Actavis without prejudice, and Actavis agreed that the related Actavis entities would be bound to judgments and orders of the court against Actavis and would be subject to discovery as if they were parties. In September 2015, the court entered a scheduling order, setting a claim construction hearing for May 2016 and a three-day bench trial to begin in June 2017. After reviewing Actavis’ ANDA, the Company and Takeda subsequently dropped U.S. Patent Nos. 8,088,786, 8,318,788, 8,722,085 and 8,815,889 from the lawsuit. In April 2016, the Company and Takeda filed an amended complaint against Actavis asserting newly issued U.S. Patent No. 9,125,868. In June 2016, in response to the May 2016 claim construction hearing, the court adopted the Company’s proposed constructions for the majority of the disputed claim terms. In August 2016, in connection with the end of the transition period associated with the Separation Agreement entered into between the Company and Takeda, Takeda transferred responsibility for management of this patent infringement lawsuit to the Company. The bench trial for this matter commenced on June 5, 2017, in connection with which the Company agreed to drop U.S. Patent No. 9,125,868 from the lawsuit. On October 13, 2017, the District Court issued its opinion and found that the claims in the three patents at issue (U.S. Patent Nos. 7,462,626, 7,375,111, and 8,916,195, which expire in 2024, 2025 and 2030, respectively) were valid and infringed. Actavis has 30 days from the District Court’s entry of judgment in the matter, which occurred on October 26, 2017, to appeal the District Court’s decision. Although the Company plans to continue to vigorously enforce Contrave intellectual property rights, there are uncertainties inherent in any litigation and appeal and the Company cannot predict the outcome.

14. Litigation

On March 10, 2015, a purported class action lawsuit was filed against the Company and certain of the Company’s officers in the United States District Court for the Southern District of California, captioned Colley v. Orexigen, et al. The following day, two additional putative class action lawsuits were filed in the same court, captioned Stefanko v. Orexigen, et al., and Yantz v. Orexigen, et al., asserting substantially similar claims. On June 22, 2015, the court consolidated the lawsuits and appointed a lead plaintiff. On August 20, 2015, the lead plaintiff filed a consolidated complaint. The consolidated complaint purports to assert claims on behalf of a class of purchasers of the Company’s stock between March 3, 2015 and May 12, 2015. It alleges that defendants violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 by purportedly making false and misleading statements regarding the interim results and termination of the Light Study. The consolidated complaint seeks an unspecified amount of damages, attorneys’ fees and equitable or injunctive relief. On October 5, 2015, defendants filed a motion to dismiss the consolidated complaint. On May 19, 2016, the District Court granted the motion to dismiss, dismissing portions of the consolidated complaint with prejudice and portions without prejudice. The Court granted the lead plaintiff 30 days to file an amended complaint with respect to those portions not dismissed with prejudice. On June 16, 2016, the lead plaintiff filed a notice of intent not to file an amended complaint but to proceed directly to an appeal of the Court’s decision dismissing the consolidated complaint. As a result, the court entered judgment dismissing the consolidated complaint with prejudice on June 27, 2016. The lead plaintiff filed a Notice of Appeal with the Ninth Circuit Court of Appeals on July 26, 2016. On November 6, 2017, the Ninth Circuit held oral arguments on the appeal but has not yet issued its decision. Although management believes that this appeal lacks merit and intends to defend against it vigorously, there are uncertainties inherent in any litigation and the Company cannot predict the outcome. At this time, the Company is unable to estimate possible losses or ranges of losses that may result from such legal proceedings, and it has not accrued any amounts in connection with such legal proceedings other than ongoing attorney’s fees.

On June 3, 2016, plaintiff Ben Wilkin, a shareholder who had previously made a shareholder demand to inspect certain books and records of the Company, filed a derivative lawsuit purportedly on behalf of the Company against certain of the Company’s current and former officers and members of the board of directors in the Delaware Chancery Court, captioned Wilkin v. Narachi, et al. The lawsuit asserts claims for breach of fiduciary duty and waste of corporate assets based on essentially the same set of facts underlying the Colley, Stefanko and Yantz consolidated class action. The lawsuit seeks, among other things, damages, corporate governance reforms, injunctive relief, restitution, disgorgement and attorney’s fees. Orexigen and the individual defendants filed a motion to dismiss on October 31, 2016, asserting that plaintiff failed to plead demand futility and otherwise failed to state a claim. Instead of opposing the motion to dismiss, on January 13, 2017, plaintiff filed an amended complaint pursuant to Chancery Rule 15(aaa). The amended complaint asserts nearly identical allegations and claims as the original complaint. Orexigen and the individual defendants filed a motion to dismiss on March 27, 2017. A hearing on Orexigen’s and the individual defendants’ motion to dismiss is scheduled for November 17, 2017. Management believes that the claims lack merit and intends to defend against them vigorously. The Company is unable to estimate possible losses or ranges of losses that may result from this lawsuit and has not accrued any amounts in connection with this suit.

It is possible that additional securities class action litigation may be brought against the Company following stock price declines related to the release of information regarding Contrave or clinical trial results, including the Light Study. Any adverse determination in such litigation could subject the Company to significant liabilities.

In April 2015, the Company and Takeda received a Paragraph IV certification notice letter regarding an abbreviated new drug application, or ANDA, submitted to the FDA by Actavis Laboratories FL, Inc., or Actavis, requesting approval to market, sell, and use a generic version of Contrave. In its notice letter, Actavis alleged that U.S. Patent Nos. 7,375,111, 7,462,626, 8,088,786, 8,318,788, 8,722,085, 8,815,889, and 8,916,195, which are listed in the FDA’s Approved Drug Products with Therapeutic Equivalence Evaluations, or the Orange Book, for Contrave, are invalid, unenforceable and/or would not be infringed by Actavis’ manufacture, use or sale of the product described in its ANDA. In June 2015, the Company and Takeda filed a patent infringement lawsuit in the U.S. District Court for the District of Delaware against Actavis and certain of its affiliates related to the ANDA previously filed by Actavis and described above. The lawsuit claims infringement of the seven patents that were the subject of Actavis’ notice letter, as described above. In accordance with the Drug Price Competition and Patent Term Restoration Act of 1984, known as the Hatch-Waxman Act, as a result of having filed a patent infringement lawsuit within 45 days of receipt of Actavis’ notice letter, FDA approval of the ANDA was stayed until the earlier of (i) 30 months from the date of receipt of the notice letter or (ii) a District Court decision finding that the identified patents were invalid, unenforceable or not infringed. In July 2015, Actavis filed an answer, affirmative defenses and counterclaim to the Company’s and Takeda’s complaint, and the Company and Takeda filed an answer to Actavis’ counterclaim in August 2015. Moreover, in July 2015, the court ordered a stipulation between the Company, Takeda and Actavis in which Orexigen and Takeda agreed to dismiss all defendants except Actavis without prejudice, and Actavis agreed that the related Actavis entities would be bound to judgments and orders of the court against Actavis and would be subject to discovery as if they were parties. In September 2015, the court entered a scheduling order, setting a claim construction hearing for May 2016 and a three-day bench trial to begin in June 2017. After reviewing Actavis’ ANDA, the Company and Takeda subsequently dropped U.S. Patent Nos. 8,088,786, 8,318,788, 8,722,085 and 8,815,889 from the lawsuit. In April 2016, the Company and Takeda filed an amended complaint against Actavis asserting newly issued U.S. Patent No. 9,125,868. In June 2016, in response to the May 2016 claim construction hearing, the court adopted the Company’s proposed constructions for the majority of the disputed claim terms. In August 2016, in connection with the end of the transition period associated with the Separation Agreement entered into between the Company and Takeda, Takeda transferred responsibility for management of this patent infringement lawsuit to the Company. The bench trial for this matter commenced on June 5, 2017, in connection with which the Company agreed to drop U.S. Patent No. 9,125,868 from the lawsuit. On October 13, 2017, the District Court issued its opinion and found that the claims in the three patents at issue (U.S. Patent Nos. 7,462,626, 7,375,111, and 8,916,195, which expire in 2024, 2025 and 2030, respectively) were valid and infringed. Actavis has 30 days from the District Court’s entry of judgment in the matter, which occurred on October 26, 2017, to appeal the District Court’s decision. Although the Company plans to continue to vigorously enforce Contrave intellectual property rights, there are uncertainties inherent in any litigation and appeal and the Company cannot predict the outcome.