Legal Proceedings	12 Months Ended
Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Legal Proceedings	Legal Proceedings In Re: Taxotere (Docetaxel) On February 1, 2017, the Company was named as a defendant, among various other manufacturers, in several product liability suits that are consolidated in the U.S. District Court for the Eastern District of Louisiana as part of MDL 2740 (Civil Action No 2:16 md-2740). The claims are for personal injuries allegedly arising out of the use of docetaxel. In March 2017, the Company reached agreements in principle with the Plaintiffs’ Steering Committee in this matter to voluntarily dismiss the Company from all of the lawsuits in which it was named and from the master complaint. The Company is in the process of working with the other parties in this matter to have it removed from the Multidistrict litigation entirely. As part of the agreement, in the event a case is brought in the future with facts that justify the Company’s inclusion, the plaintiffs reserved the right to include the Company in such matter. The plaintiffs have filed several additional lawsuits since the parties’ agreement in principle to dismiss, and the Company is in the process of working with plaintiffs to explore the possibility of dismissing those lawsuits. The Company believes that it has substantial meritorious defenses to these cases and maintains product liability insurance against such cases. However, litigation is inherently uncertain and the Company cannot predict the outcome of this litigation. These actions, if successful, or if our indemnification arrangements or insurance do not provide sufficient coverage against such claims, could adversely affect the Company and could have a material adverse effect on the Company’s business, results of operations, financial condition and cash flows. Medicines Company v. Eagle On February 2, 2016, The Medicines Company (“MDCO”) filed a complaint in the U.S. District Court for the District of New Jersey against the Company, SciDose LLC and TherDose Pharma Pvt. Ltd. (collectively the “Defendants”) relating to the Defendants’ work on a novel ready-to-use bivalirudin injection product (“EP-6101”). MDCO amended that complaint in April of 2016. The complaint cites the May 7, 2008 License and Development Agreement (the “LDA”) between the Defendants and MDCO, which was terminated by the Company on September 17, 2013. In October 2017, the Defendants moved to dismiss the action for lack of subject matter jurisdiction and to stay discovery. In December 2017, while those motions were pending, the parties entered into a settlement agreement pursuant to which Defendants agreed to pay $1.7 million and assign to MDCO all intellectual property rights relating to EP-6101. As a result of the settlement, the parties entered into a stipulation dismissing all claims with prejudice. Bauer v. Eagle On May 31, 2016, a federal securities class-action lawsuit (captioned Bauer v. Eagle Pharmaceuticals, Inc., et al., Case No. 16-cv-03091-JLL-JAD) was filed in the United States District Court for the District of New Jersey against the Company and the Company’s Chief Executive Officer. On August 1, 2016, plaintiffs Blake Bauer, Brent Kawamura and Guarang Patel (the "EGRX Investors Group"), filed a motion requesting the Court to appoint the EGRX Investors Group as lead plaintiff and Kirby McInerney LLP as lead counsel. The motion was granted on September 9, 2016. On October 31, 2016, the EGRX Investors Group filed an amended class action complaint (the “Amended Complaint”) against the defendants, seeking compensatory damages and an award of costs and expenses, including attorneys’ and experts’ fees. The Amended Complaint alleged that defendants violated sections 10(b) and 20(a) of the Securities Exchange Act, as amended, by making false and/or misleading statements about, among other things: (a) EP-6101, (b) the Company’s expectations regarding the NDA submitted for EP-6101, and (c) the Company’s business prospects. On December 16, 2016, defendants filed a motion to dismiss the Amended Complaint. Plaintiffs opposed that motion on January 30, 2017. Defendants filed their reply on March 1, 2017. On May 19, 2017, the Court granted defendants motion to dismiss and dismissed the Amended Complaint without prejudice. On June 1, 2017, the Court entered an order granting plaintiffs until July 3, 2017 to file an amended complaint. Plaintiffs did not file an amended complaint on or before July 3, 2017 and, therefore, on August 2, 2017, the Court entered an order dismissing the case with prejudice and directing the clerk to close the case. On August 31, 2017, plaintiffs filed a notice of appeal to the United States Court of Appeals for the Third Circuit, indicating their intent to appeal from the Court’s May 19, 2017 and August 2, 2017 orders. On October 4, 2017, plaintiffs-appellants filed a motion to withdraw their appeal and, on October 5, 2017, the Court of Appeals issued an order dismissing the appeal without costs to either party. Eagle v. Burwell On April 27, 2016, the Company filed an action in the U.S. District Court for the District of Columbia against the FDA and other federal defendants seeking an order requiring the FDA to grant us orphan drug exclusivity for Bendeka for the treatment of CLL and indolent B-cell NHL. The Company believes Bendeka is entitled to orphan drug exclusivity as a matter of law, and that the FDA’s decision violates federal law and is inconsistent with the holding of the U.S. District Court for the District of Columbia in Depomed Inc. v. U.S. Department of Health and Human Services. The parties have filed all substantive motions and pleadings and anticipate either a schedule for oral argument or a disposition from the court in 2018. Eagle v. Eli Lilly On August 24, 2017, the Company filed an antitrust complaint in the United States District Court for the District of New Jersey against Eli Lilly and Company (“Lilly”), Case No. 2:17-CV-06415. The complaint alleges that Lilly engaged in anticompetitive conduct which restrained competition by delaying and blocking the Company’s launch of a competing pemetrexed injection product (to compete with Lilly’s Alimta). Lilly has accepted service and answered the complaint on October 27, 2017. Lily also filed a motion to transfer this case to Delaware on October 27, 2017. Eagle filed a motion to oppose such transfer on November 6, 2017. No other dates or proceedings have been scheduled as of the date of the filing of this Annual Report on Form 10-K. The Company believes it has valid claims against Lilly and the right to seek injunctive relief and damages. However, litigation is inherently uncertain, and the Company cannot predict the outcome of this litigation. Patent Litigation Eli Lilly and Company. v. Eagle Pharmaceuticals, Inc. (PEMFEXY^TM (Pemetrexed)) On August 14, 2017, Lilly filed suit against the Company in the United States District Court for the Southern District of Indiana (the “Indiana Suit”). Lilly alleged patent infringement based on the filing of the Company’s 505(b)(2) NDA seeking approval to manufacture and sell the Company’s EP-5101. EP-5101, if finally approved by FDA, will be a branded alternative to Alimta®, which is indicated (in combination with cisplatin) (a) for the treatment of patients with malignant pleural mesothelioma, or (b) for the initial treatment of locally advanced or metastatic nonsquamous non-small cell lung cancer. Alimta® also is indicated as a single-agent for the treatment of patients with locally advanced or metastatic nonsquamous non-small cell lung cancer after prior chemotherapy. Alimta® also is indicated for maintenance treatment of patients with locally advanced or metastatic nonsquamous non-small cell lung cancer whose disease has not progressed after four cycles of platinum-based first-line chemotherapy. On September 8, 2017, Eagle moved to dismiss the Indiana Suit for improper venue. On September 11, 2017, Lilly voluntarily dismissed the Indiana Suit. It then filed a complaint in the United States District Court for the District of Delaware, alleging similar patent infringement claims (the “Delaware Suit”). Eagle answered and filed various counterclaims in the Delaware Suit on October 3, 2017. Lilly answered Eagle’s counterclaims on October 24, 2017. The Court held a scheduling conference on December 11, 2017 and set trial in the Delaware Suit to begin on September 9, 2019. The Delaware Suit is pending. Eagle Pharmaceuticals, Inc., et al. v. Slayback Pharma Limited Liability Company; Eagle Pharmaceuticals, Inc., et al. v. Apotex Inc. and Apotex Corp.; Eagle Pharmaceuticals, Inc., et al. v. Fresenius Kabi USA, LLC; Eagle Pharmaceuticals, Inc., et al. v. Mylan Laboratories Limited - (BENDEKA®) BENDEKA®, which contains bendamustine hydrochloride, is an alkylating drug that is indicated for the treatment of patients with chronic lymphocytic leukemia, as well as for the treatment of patients with indolent B-cell non-Hodgkin's lymphoma that has progressed during or within six months of treatment with rituximab or a rituximab-containing regimen. Four companies - Slayback Pharma Limited Liability Company (“Slayback”), Apotex Inc. and Apotex Corp. (“Apotex”), Fresenius Kabi USA, LLC (“Fresenius”), and Mylan Laboratories Limited (“Mylan”) - have filed Abbreviated New Drug Applications (“ANDA’s”) referencing BENDEKA® that include challenges to one or more of the BENDEKA® Orange Book-listed patents. The Company, Cephalon, Inc. and/or Teva Pharmaceuticals International GMBH (together the “Patentees”), filed separate suits against Slayback, Apotex, Fresenius and Mylan in the United States District Court for the District of Delaware on August 16, 2017 (Slayback (“Slayback I”)), August 18, 2017 (Apotex), August 24, 2017 (Fresenius), December 12, 2017 (Mylan), and January 19, 2018 (Slayback (“Slayback II”)). In these Complaints, the Patentees allege infringement of the challenged patents, namely U.S. Patent Nos. 8,791,270 and 9,572,887 against Slayback (Slayback I and Slayback II), and of U.S. Patent Nos. 8,609,707, 8,791,270, 9,000,021, 9,034,908, 9,144,568, 9,265,831, 9,572,796, 9,572,797, 9,572,887, 9,579,384, 9,597,397, 9,597,398, 9,597,399 against Fresenius, Apotex, and Mylan. Slayback, Apotex, Fresenius, and Mylan answered their Complaints and some filed various counterclaims on September 29, 2017 (Slayback I), February 12, 2018 (Slayback II), November 27, 2017, September 15, 2017, and February 14, 2018, respectively. The Patentees answered the Slayback I, Fresenius, and Apotex counterclaims on October 20, 2017, October 6, 2017, and December 18, 2017, respectively. The Slayback I, Apotex, Fresenius and Mylan cases have been consolidated for all purposes, with Trial scheduled to begin September 3, 2019. All five cases are pending. The FDA is stayed from approving Apotex’s, Fresenius’, and Mylan’s ANDA’s until the earlier of (1) January 7, 2020, January 14, 2020, and April 30, 2020, respectively (the “30-month stay dates”); and (2) a court decision that each of the challenged patents is not infringed, invalid or unenforceable. The 30-month stay dates may be shortened or lengthened if either party to the action fails to reasonably cooperate in expediting the action. The FDA cannot approve Slayback’s ANDA until March 2033.

Legal Proceedings

In Re: Taxotere (Docetaxel)

On February 1, 2017, the Company was named as a defendant, among various other manufacturers, in several product liability suits that are consolidated in the U.S. District Court for the Eastern District of Louisiana as part of MDL 2740 (Civil Action No 2:16 md-2740). The claims are for personal injuries allegedly arising out of the use of docetaxel.

In March 2017, the Company reached agreements in principle with the Plaintiffs’ Steering Committee in this matter to voluntarily dismiss the Company from all of the lawsuits in which it was named and from the master complaint. The Company is in the process of working with the other parties in this matter to have it removed from the Multidistrict litigation entirely. As part of the agreement, in the event a case is brought in the future with facts that justify the Company’s inclusion, the plaintiffs reserved the right to include the Company in such matter. The plaintiffs have filed several additional lawsuits since the parties’ agreement in principle to dismiss, and the Company is in the process of working with plaintiffs to explore the possibility of dismissing those lawsuits. The Company believes that it has substantial meritorious defenses to these cases and maintains product liability insurance against such cases. However, litigation is inherently uncertain and the Company cannot predict the outcome of this litigation. These actions, if successful, or if our indemnification arrangements or insurance do not provide sufficient coverage against such claims, could adversely affect the Company and could have a material adverse effect on the Company’s business, results of operations, financial condition and cash flows.

Medicines Company v. Eagle

On February 2, 2016, The Medicines Company (“MDCO”) filed a complaint in the U.S. District Court for the District of New Jersey against the Company, SciDose LLC and TherDose Pharma Pvt. Ltd. (collectively the “Defendants”) relating to the Defendants’ work on a novel ready-to-use bivalirudin injection product (“EP-6101”). MDCO amended that complaint in April of 2016. The complaint cites the May 7, 2008 License and Development Agreement (the “LDA”) between the Defendants and MDCO, which was terminated by the Company on September 17, 2013. In October 2017, the Defendants moved to dismiss the action for lack of subject matter jurisdiction and to stay discovery. In December 2017, while those motions were pending, the parties entered into a settlement agreement pursuant to which Defendants agreed to pay $1.7 million and assign to MDCO all intellectual property rights relating to EP-6101. As a result of the settlement, the parties entered into a stipulation dismissing all claims with prejudice.

Bauer v. Eagle

On May 31, 2016, a federal securities class-action lawsuit (captioned Bauer v. Eagle Pharmaceuticals, Inc., et al., Case No. 16-cv-03091-JLL-JAD) was filed in the United States District Court for the District of New Jersey against the Company and the Company’s Chief Executive Officer. On August 1, 2016, plaintiffs Blake Bauer, Brent Kawamura and Guarang Patel (the "EGRX Investors Group"), filed a motion requesting the Court to appoint the EGRX Investors Group as lead plaintiff and Kirby McInerney LLP as lead counsel. The motion was granted on September 9, 2016. On October 31, 2016, the EGRX Investors Group filed an amended class action complaint (the “Amended Complaint”) against the defendants, seeking compensatory damages and an award of costs and expenses, including attorneys’ and experts’ fees. The Amended Complaint alleged that defendants violated sections 10(b) and 20(a) of the Securities Exchange Act, as amended, by making false and/or misleading statements about, among other things: (a) EP-6101, (b) the Company’s expectations regarding the NDA submitted for EP-6101, and (c) the Company’s business prospects. On December 16, 2016, defendants filed a motion to dismiss the Amended Complaint. Plaintiffs opposed that motion on January 30, 2017. Defendants filed their reply on March 1, 2017. On May 19, 2017, the Court granted defendants motion to dismiss and dismissed the Amended Complaint without prejudice. On June 1, 2017, the Court entered an order granting plaintiffs until July 3, 2017 to file an amended complaint. Plaintiffs did not file an amended complaint on or before July 3, 2017 and, therefore, on August 2, 2017, the Court entered an order dismissing the case with prejudice and directing the clerk to close the case. On August 31, 2017, plaintiffs filed a notice of appeal to the United States Court of Appeals for the Third Circuit, indicating their intent to appeal from the Court’s May 19, 2017 and August 2, 2017 orders. On October 4, 2017, plaintiffs-appellants filed a motion to withdraw their appeal and, on October 5, 2017, the Court of Appeals issued an order dismissing the appeal without costs to either party.

Eagle v. Burwell

On April 27, 2016, the Company filed an action in the U.S. District Court for the District of Columbia against the FDA and other federal defendants seeking an order requiring the FDA to grant us orphan drug exclusivity for Bendeka for the treatment of CLL and indolent B-cell NHL. The Company believes Bendeka is entitled to orphan drug exclusivity as a matter of law, and that the FDA’s decision violates federal law and is inconsistent with the holding of the U.S. District Court for the District of Columbia in Depomed Inc. v. U.S. Department of Health and Human Services. The parties have filed all substantive motions and pleadings and anticipate either a schedule for oral argument or a disposition from the court in 2018.

Eagle v. Eli Lilly

On August 24, 2017, the Company filed an antitrust complaint in the United States District Court for the District of New Jersey against Eli Lilly and Company (“Lilly”), Case No. 2:17-CV-06415. The complaint alleges that Lilly engaged in anticompetitive conduct which restrained competition by delaying and blocking the Company’s launch of a competing pemetrexed injection product (to compete with Lilly’s Alimta). Lilly has accepted service and answered the complaint on October 27, 2017. Lily also filed a motion to transfer this case to Delaware on October 27, 2017. Eagle filed a motion to oppose such transfer on November 6, 2017. No other dates or proceedings have been scheduled as of the date of the filing of this Annual Report on Form 10-K. The Company believes it has valid claims against Lilly and the right to seek injunctive relief and damages. However, litigation is inherently uncertain, and the Company cannot predict the outcome of this litigation.

Patent Litigation

Eli Lilly and Company. v. Eagle Pharmaceuticals, Inc. (PEMFEXY^TM (Pemetrexed))

On August 14, 2017, Lilly filed suit against the Company in the United States District Court for the Southern District of Indiana (the “Indiana Suit”). Lilly alleged patent infringement based on the filing of the Company’s 505(b)(2) NDA seeking approval to manufacture and sell the Company’s EP-5101. EP-5101, if finally approved by FDA, will be a branded alternative to Alimta®, which is indicated (in combination with cisplatin) (a) for the treatment of patients with malignant pleural mesothelioma, or (b) for the initial treatment of locally advanced or metastatic nonsquamous non-small cell lung cancer. Alimta® also is indicated as a single-agent for the treatment of patients with locally advanced or metastatic nonsquamous non-small cell lung cancer after prior chemotherapy. Alimta® also is indicated for maintenance treatment of patients with locally advanced or metastatic nonsquamous non-small cell lung cancer whose disease has not progressed after four cycles of platinum-based first-line chemotherapy.

On September 8, 2017, Eagle moved to dismiss the Indiana Suit for improper venue. On September 11, 2017, Lilly voluntarily dismissed the Indiana Suit. It then filed a complaint in the United States District Court for the District of Delaware, alleging similar patent infringement claims (the “Delaware Suit”). Eagle answered and filed various counterclaims in the Delaware Suit on October 3, 2017. Lilly answered Eagle’s counterclaims on October 24, 2017. The Court held a scheduling conference on December 11, 2017 and set trial in the Delaware Suit to begin on September 9, 2019. The Delaware Suit is pending.

Eagle Pharmaceuticals, Inc., et al. v. Slayback Pharma Limited Liability Company; Eagle Pharmaceuticals, Inc., et al. v. Apotex Inc. and Apotex Corp.; Eagle Pharmaceuticals, Inc., et al. v. Fresenius Kabi USA, LLC; Eagle Pharmaceuticals, Inc., et al. v. Mylan Laboratories Limited - (BENDEKA®)

BENDEKA®, which contains bendamustine hydrochloride, is an alkylating drug that is indicated for the treatment of patients with chronic lymphocytic leukemia, as well as for the treatment of patients with indolent B-cell non-Hodgkin's lymphoma that has progressed during or within six months of treatment with rituximab or a rituximab-containing regimen. Four companies - Slayback Pharma Limited Liability Company (“Slayback”), Apotex Inc. and Apotex Corp. (“Apotex”), Fresenius Kabi USA, LLC (“Fresenius”), and Mylan Laboratories Limited (“Mylan”) - have filed Abbreviated New Drug Applications (“ANDA’s”) referencing BENDEKA® that include challenges to one or more of the BENDEKA® Orange Book-listed patents.

The Company, Cephalon, Inc. and/or Teva Pharmaceuticals International GMBH (together the “Patentees”), filed separate suits against Slayback, Apotex, Fresenius and Mylan in the United States District Court for the District of Delaware on August 16, 2017 (Slayback (“Slayback I”)), August 18, 2017 (Apotex), August 24, 2017 (Fresenius), December 12, 2017 (Mylan), and January 19, 2018 (Slayback (“Slayback II”)). In these Complaints, the Patentees allege infringement of the challenged patents, namely U.S. Patent Nos. 8,791,270 and 9,572,887 against Slayback (Slayback I and Slayback II), and of U.S. Patent Nos. 8,609,707, 8,791,270, 9,000,021, 9,034,908, 9,144,568, 9,265,831, 9,572,796, 9,572,797, 9,572,887, 9,579,384, 9,597,397, 9,597,398, 9,597,399 against Fresenius, Apotex, and Mylan. Slayback, Apotex, Fresenius, and Mylan answered their Complaints and some filed various counterclaims on September 29, 2017 (Slayback I), February 12, 2018 (Slayback II), November 27, 2017, September 15, 2017, and February 14, 2018, respectively. The Patentees answered the Slayback I, Fresenius, and Apotex counterclaims on October 20, 2017, October 6, 2017, and December 18, 2017, respectively. The Slayback I, Apotex, Fresenius and Mylan cases have been consolidated for all purposes, with Trial scheduled to begin September 3, 2019. All five cases are pending.

The FDA is stayed from approving Apotex’s, Fresenius’, and Mylan’s ANDA’s until the earlier of (1) January 7, 2020, January 14, 2020, and April 30, 2020, respectively (the “30-month stay dates”); and (2) a court decision that each of the challenged patents is not infringed, invalid or unenforceable. The 30-month stay dates may be shortened or lengthened if either party to the action fails to reasonably cooperate in expediting the action. The FDA cannot approve Slayback’s ANDA until March 2033.