Commitments and Contingent Liabilities	12 Months Ended
Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	19. COMMITMENTS AND CONTINGENT LIABILITIES Litigation From time to time, the Company may be subject to legal proceedings and claims in the ordinary course of business. On a quarterly basis, the Company reviews the status of each significant matter and assesses its potential financial exposure. If the potential loss from any claim, asserted or unasserted, or legal proceeding is considered probable and the amount can be reasonably estimated, the Company would accrue a liability for the estimated loss. Because of uncertainties related to claims and litigation, accruals are based on the Company’s best estimates based on available information. On a periodic basis, as additional information becomes available, or based on specific events such as the outcome of litigation or settlement of claims, the Company may reassess the potential liability related to these matters and may revise these estimates, which could result in material adverse adjustments to the Company’s operating results. At December 31, 2019, there were no potential material losses from claims, asserted or unasserted, or legal proceedings that the Company determined were probable of occurring. INVEGA SUSTENNA ANDA Litigation In January 2018 and in August 2019, Janssen Pharmaceuticals NV and Janssen Pharmaceuticals, Inc. initiated patent infringement lawsuits in the United States District Court for the District of New Jersey against Teva entities (Teva Pharmaceuticals USA, Inc.(“Teva”) and Teva Pharmaceuticals Industries, Ltd. (“Teva PI”)) and Mylan entities (Mylan Laboratories Limited (“Mylan Labs”), Mylan Pharmaceuticals Inc. (“Mylan”), and Mylan Institutional LLC), respectively, following filings by each of Teva and Mylan Labs of an abbreviated new drug application (“ANDA”) seeking approval to market a generic version of INVEGA SUSTENNA before the expiration of U.S. Patent No. 9,439,906. Requested judicial remedies in each of the lawsuits included recovery of litigation costs and injunctive relief. The Company is not a party to either of these proceedings. For information about risks relating to the INVEGA SUSTENNA Paragraph IV litigation, see “Item 1A—Risk Factors” in this Annual Report and specifically the section entitled “—We or our licensees may face claims against intellectual property rights covering our products and competition from generic drug manufacturers.” AMPYRA ANDA Litigation Eleven separate Paragraph IV Certification Notices had been received by the Company and/or its partner Acorda from: Accord Healthcare, Inc. (“Accord”); Actavis Laboratories FL, Inc. (“Actavis”); Alkem Laboratories Ltd. (“Alkem”); Apotex Corporation and Apotex, Inc. (collectively, “Apotex”); Aurobindo Pharma Ltd. (“Aurobindo”); MicroLabs Limited (“MicroLabs”); Mylan; Par Pharmaceutical, Inc. (“Par”); Roxane Laboratories, Inc. (“Roxane”); Sun Pharmaceutical Industries Limited and Sun Pharmaceuticals Industries Inc. (collectively, “Sun”); and Teva (collectively with Accord, Actavis, Alkem, Apotex, Aurobindo, MicroLabs, Mylan, Par, Roxane and Sun, the “ANDA Filers”) advising that each of the ANDA Filers had submitted an ANDA to the FDA seeking marketing approval for generic versions of AMPYRA (dalfampridine) Extended-Release Tablets, 10 mg. The ANDA Filers challenged the validity of one or more of the Orange Book-listed patents for AMPYRA, and they also asserted that their generic versions do not infringe certain claims of these patents. In response, the Company and/or Acorda filed lawsuits against the ANDA Filers asserting infringement of one or more of the Orange Book-listed patents for AMPYRA. Requested judicial remedies included recovery of litigation costs and injunctive relief. All lawsuits were filed within 45 days from the date of receipt of each of the Paragraph IV Certification Notices from the ANDA Filers. As a result, a 30-month statutory stay of approval period applied to each of the ANDA Filers’ ANDAs under the U.S. Drug Price Competition and Patent Term Restoration Act of 1984 (the “Hatch-Waxman Act”). The first 30-month stay restricted the FDA from approving the ANDA Filers’ ANDAs until July 2017 at the earliest, unless a Federal district court issued a decision adverse to all of the asserted Orange Book-listed patents prior to that date. Lawsuits with eight of the ANDA Filers were consolidated into a single case. The Company and/or Acorda entered into a settlement agreement with each of Accord, Actavis, Alkem, Apotex, Aurobindo, MicroLabs, Par and Sun to resolve the patent litigation that the Company and/or Acorda brought against these settling ANDA Filers. The settlements with these settling ANDA Filers did not impact the patent litigation that the Company and Acorda brought against the remaining ANDA Filers, including as described below. In March 2017, after a bench trial, the U.S. District Court for the District of Delaware (the “Delaware Court”) issued an opinion (the “Delaware Court Decision”), which, among other things, invalidated U.S. Patent Nos. 8,007,826; 8,354,437; 8,440,703; and 8,663,685. The Delaware Court also upheld the validity of the U.S. Patent No. 5,540,938, which pertained to the formulation of AMPYRA, but that patent expired on July 30, 2018. In May 2017, Acorda filed an appeal with the Federal Circuit of the Delaware Court Decision with respect to the findings on U.S. Patent Nos. 8,007,826; 8,354,437; 8,440,703; and 8,663,685. On September 10, 2018, the Federal Circuit affirmed the Delaware Court Decision, which invalidated U.S. Patent Nos. 8,007,826; 8,354,437; 8,440,703; and 8,663,685. In October 2018, Acorda filed a petition for rehearing and rehearing en banc of the Federal Circuit’s decision. In January 2019, the Federal Circuit denied Acorda’s petition. In April 2019, Acorda filed a petition for writ of certiorari to the Supreme Court of the United States (the “Supreme Court”). On October 7, 2019, the Supreme Court denied Acorda’s petition requesting review of the case, rendering the Federal Circuit decision as final. For information about risks relating to the AMPYRA Paragraph IV litigations and other proceedings see “Item 1A—Risk Factors” of this Annual Report and specifically the section entitled “—We or our licensees may face claims against intellectual property rights covering our products and competition from generic drug manufacturers.” RISPERDAL CONSTA European Opposition Proceedings In December 2016, Nanjing Luye Pharmaceutical Co., Ltd., Pharmathen SA, Teva PI and Dehns Ltd (a law firm representing an unidentified opponent) filed notices of opposition with the European Patent Office (the “EPO”) in respect of EP 2 269 577 B (the “EP ’577” Patent), which is a patent directed to certain risperidone microsphere compositions, including RISPERDAL CONSTA. Following a hearing on the matter in January 2019, the EPO issued a written decision revoking the EP’577 Patent in April 2019. The Company filed a notice of appeal of the decision to the EPO’s Technical Boards of Appeal in June 2019. Pharmathen SA submitted a reply on November 5, 2019. The Company will continue to vigorously defend the EP ’577 Patent. For information about risks relating to the EP ’577 Patent opposition proceedings see “Item 1A—Risk Factors” in this Annual Report, including the sections entitled “—Patent protection for our products is important and uncertain” and “—Uncertainty over intellectual property in the biopharmaceutical industry has been the source of litigation, which is inherently costly and unpredictable, could significantly delay or prevent approval or commercialization of our products, and could adversely affect our business.” RISPERDAL CONSTA ANDA Litigation On July 17, 2019, the Company, together with Janssen Pharmaceuticals, Inc., initiated a patent infringement lawsuit in the United States District Court for the District of Delaware (the “Delaware District Court”) against Luye Pharma Group Ltd., Luye Pharma (USA) Ltd., Nanjing Luye Pharmaceutical Co., Ltd. and Shandong Luye Pharmaceutical Co., Ltd. (collectively, “Luye”). Luye filed a 505(b)(2) NDA seeking approval to market a competing product to RISPERDAL CONSTA before the expiration of U.S. Patent No. 6,667,061. Requested judicial remedies included, among other things, recovery of litigation costs and injunctive relief. On July 23, 2019, Luye filed its answer and affirmative defenses. On November 22, 2019, the parties submitted a stipulation and order of dismissal to the Delaware District Court stating that the parties had resolved the litigation. On December 2, 2019, the Delaware District Court signed the stipulation and order of dismissal terminating the lawsuit. Government Matters On June 22, 2017 and January 17, 2019, the Company received a subpoena and a civil investigative demand, respectively, each from an Office of the U.S. Attorney for documents related to VIVITROL. The Company is cooperating with the government. Securities Litigation In December 2018 and January 2019, purported stockholders of the Company filed putative class actions against the Company and certain of its officers in the United States District Court for the Eastern District of New York (the “EDNY District Court”) captioned Karimian v. Alkermes plc, et al., No. 1:18-cv-07410 and McDermott v. Alkermes plc, et al., No. 1:19-cv-00624, respectively. In March 2019, the EDNY District Court consolidated the two cases and appointed a lead plaintiff. The plaintiff filed an amended complaint on July 9, 2019 naming one additional officer of the Company and one former officer of the Company as defendants. The amended complaint was filed on behalf of a putative class of purchasers of Alkermes securities during the period of July 31, 2014 through November 1, 2018 and alleges violations of Sections 10(b) and 20(a) of the Exchange Act based on allegedly false or misleading statements and omissions regarding the Company’s clinical methodologies and regulatory submission for ALKS 5461 and the FDA’s review and consideration of that submission. The lawsuit seeks, among other things, unspecified money damages, prejudgment and postjudgment interest, reasonable attorneys’ fees, expert fees and other costs. In August 2019, the defendants filed a pre-motion letter (in respect of a requested motion to dismiss filing) with the EDNY District Court and plaintiff filed a response. On November 27, 2019, the defendants served the plaintiff with a motion to dismiss, and on December 27, 2019, the plaintiff served the defendants with its opposition to such motion. On January 17, 2020, the defendants filed the fully-briefed motion, including a reply to the plaintiff’s opposition, with the EDNY District Court. For information about risks relating to this action, see “Item 1A—Risk Factors” in the Annual Report, including the section entitled “—Litigation or arbitration against Alkermes, including securities litigation, or citizen petitions filed with the FDA, may result in financial losses, harm our reputation, divert management resources, negatively impact the approval of our products, or otherwise negatively impact our business.” Purchase Commitments The Company has open purchase orders for materials, supplies, services and property, plant and equipment as part of the normal course of business. At December 31, 2019, the Company had open purchase orders totaling $395.3 million and $33.5 million for non-capital and capital commitments, respectively.

Commitments and Contingent Liabilities

12 Months Ended

Dec. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

19. COMMITMENTS AND CONTINGENT LIABILITIES

Litigation

From time to time, the Company may be subject to legal proceedings and claims in the ordinary course of business. On a quarterly basis, the Company reviews the status of each significant matter and assesses its potential financial exposure. If the potential loss from any claim, asserted or unasserted, or legal proceeding is considered probable and the amount can be reasonably estimated, the Company would accrue a liability for the estimated loss. Because of uncertainties related to claims and litigation, accruals are based on the Company’s best estimates based on available information. On a periodic basis, as additional information becomes available, or based on specific events such as the outcome of litigation or settlement of claims, the Company may reassess the potential liability related to these matters and may revise these estimates, which could result in material adverse adjustments to the Company’s operating results. At December 31, 2019, there were no potential material losses from claims, asserted or unasserted, or legal proceedings that the Company determined were probable of occurring.

INVEGA SUSTENNA ANDA Litigation

In January 2018 and in August 2019, Janssen Pharmaceuticals NV and Janssen Pharmaceuticals, Inc. initiated patent infringement lawsuits in the United States District Court for the District of New Jersey against Teva entities (Teva Pharmaceuticals USA, Inc.(“Teva”) and Teva Pharmaceuticals Industries, Ltd. (“Teva PI”)) and Mylan entities (Mylan Laboratories Limited (“Mylan Labs”), Mylan Pharmaceuticals Inc. (“Mylan”), and Mylan Institutional LLC), respectively, following filings by each of Teva and Mylan Labs of an abbreviated new drug application (“ANDA”) seeking approval to market a generic version of INVEGA SUSTENNA before the expiration of U.S. Patent No. 9,439,906. Requested judicial remedies in each of the lawsuits included recovery of litigation costs and injunctive relief. The Company is not a party to either of these proceedings.

For information about risks relating to the INVEGA SUSTENNA Paragraph IV litigation, see “Item 1A—Risk Factors” in this Annual Report and specifically the section entitled “—We or our licensees may face claims against intellectual property rights covering our products and competition from generic drug manufacturers.”

AMPYRA ANDA Litigation

Eleven separate Paragraph IV Certification Notices had been received by the Company and/or its partner Acorda from: Accord Healthcare, Inc. (“Accord”); Actavis Laboratories FL, Inc. (“Actavis”); Alkem Laboratories Ltd. (“Alkem”); Apotex Corporation and Apotex, Inc. (collectively, “Apotex”); Aurobindo Pharma Ltd. (“Aurobindo”); MicroLabs Limited (“MicroLabs”); Mylan; Par Pharmaceutical, Inc. (“Par”); Roxane Laboratories, Inc. (“Roxane”); Sun Pharmaceutical Industries Limited and Sun Pharmaceuticals Industries Inc. (collectively, “Sun”); and Teva (collectively with Accord, Actavis, Alkem, Apotex, Aurobindo, MicroLabs, Mylan, Par, Roxane and Sun, the “ANDA Filers”) advising that each of the ANDA Filers had submitted an ANDA to the FDA seeking marketing approval for generic versions of AMPYRA (dalfampridine) Extended-Release Tablets, 10 mg. The ANDA Filers challenged the validity of one or more of the Orange Book-listed patents for AMPYRA, and they also asserted that their generic versions do not infringe certain claims of these patents. In response, the Company and/or Acorda filed lawsuits against the ANDA Filers asserting infringement of one or more of the Orange Book-listed patents for AMPYRA. Requested judicial remedies included recovery of litigation costs and injunctive relief.

All lawsuits were filed within 45 days from the date of receipt of each of the Paragraph IV Certification Notices from the ANDA Filers. As a result, a 30-month statutory stay of approval period applied to each of the ANDA Filers’ ANDAs under the U.S. Drug Price Competition and Patent Term Restoration Act of 1984 (the “Hatch-Waxman Act”). The first 30-month stay restricted the FDA from approving the ANDA Filers’ ANDAs until July 2017 at the earliest, unless a Federal district court issued a decision adverse to all of the asserted Orange Book-listed patents prior to that date. Lawsuits with eight of the ANDA Filers were consolidated into a single case.

The Company and/or Acorda entered into a settlement agreement with each of Accord, Actavis, Alkem, Apotex, Aurobindo, MicroLabs, Par and Sun to resolve the patent litigation that the Company and/or Acorda brought against these settling ANDA Filers. The settlements with these settling ANDA Filers did not impact the patent litigation that the Company and Acorda brought against the remaining ANDA Filers, including as described below.

In March 2017, after a bench trial, the U.S. District Court for the District of Delaware (the “Delaware Court”) issued an opinion (the “Delaware Court Decision”), which, among other things, invalidated U.S. Patent Nos. 8,007,826; 8,354,437; 8,440,703; and 8,663,685. The Delaware Court also upheld the validity of the U.S. Patent No. 5,540,938, which pertained to the formulation of AMPYRA, but that patent expired on July 30, 2018. In May 2017, Acorda filed an appeal with the Federal Circuit of the Delaware Court Decision with respect to the findings on U.S. Patent Nos. 8,007,826; 8,354,437; 8,440,703; and 8,663,685. On September 10, 2018, the Federal Circuit affirmed the Delaware Court Decision, which invalidated U.S. Patent Nos. 8,007,826; 8,354,437; 8,440,703; and 8,663,685. In October 2018, Acorda filed a petition for rehearing and rehearing en banc of the Federal Circuit’s decision. In January 2019, the Federal Circuit denied Acorda’s petition. In April 2019, Acorda filed a petition for writ of certiorari to the Supreme Court of the United States (the “Supreme Court”). On October 7, 2019, the Supreme Court denied Acorda’s petition requesting review of the case, rendering the Federal Circuit decision as final.

For information about risks relating to the AMPYRA Paragraph IV litigations and other proceedings see “Item 1A—Risk Factors” of this Annual Report and specifically the section entitled “—We or our licensees may face claims against intellectual property rights covering our products and competition from generic drug manufacturers.”

RISPERDAL CONSTA European Opposition Proceedings

In December 2016, Nanjing Luye Pharmaceutical Co., Ltd., Pharmathen SA, Teva PI and Dehns Ltd (a law firm representing an unidentified opponent) filed notices of opposition with the European Patent Office (the “EPO”) in respect of EP 2 269 577 B (the “EP ’577” Patent), which is a patent directed to certain risperidone microsphere compositions, including RISPERDAL CONSTA. Following a hearing on the matter in January 2019, the EPO issued a written decision revoking the EP’577 Patent in April 2019. The Company filed a notice of appeal of the decision to the EPO’s Technical Boards of Appeal in June 2019. Pharmathen SA submitted a reply on November 5, 2019. The Company will continue to vigorously defend the EP ’577 Patent. For information about risks relating to the EP ’577 Patent opposition proceedings see “Item 1A—Risk Factors” in this Annual Report, including the sections entitled “—Patent protection for our products is important and uncertain” and “—Uncertainty over intellectual property in the biopharmaceutical industry has been the source of litigation, which is inherently costly and unpredictable, could significantly delay or prevent approval or commercialization of our products, and could adversely affect our business.”

RISPERDAL CONSTA ANDA Litigation

On July 17, 2019, the Company, together with Janssen Pharmaceuticals, Inc., initiated a patent infringement lawsuit in the United States District Court for the District of Delaware (the “Delaware District Court”) against Luye Pharma Group Ltd., Luye Pharma (USA) Ltd., Nanjing Luye Pharmaceutical Co., Ltd. and Shandong Luye Pharmaceutical Co., Ltd. (collectively, “Luye”). Luye filed a 505(b)(2) NDA seeking approval to market a competing product to RISPERDAL CONSTA before the expiration of U.S. Patent No. 6,667,061. Requested judicial remedies included, among other things, recovery of litigation costs and injunctive relief. On July 23, 2019, Luye filed its answer and affirmative defenses. On November 22, 2019, the parties submitted a stipulation and order of dismissal to the Delaware District Court stating that the parties had resolved the litigation. On December 2, 2019, the Delaware District Court signed the stipulation and order of dismissal terminating the lawsuit.

Government Matters

On June 22, 2017 and January 17, 2019, the Company received a subpoena and a civil investigative demand, respectively, each from an Office of the U.S. Attorney for documents related to VIVITROL. The Company is cooperating with the government.

Securities Litigation

In December 2018 and January 2019, purported stockholders of the Company filed putative class actions against the Company and certain of its officers in the United States District Court for the Eastern District of New York (the “EDNY District Court”) captioned Karimian v. Alkermes plc, et al., No. 1:18-cv-07410 and McDermott v. Alkermes plc, et al., No. 1:19-cv-00624, respectively. In March 2019, the EDNY District Court consolidated the two cases and appointed a lead plaintiff. The plaintiff filed an amended complaint on July 9, 2019 naming one additional officer of the Company and one former officer of the Company as defendants. The amended complaint was filed on behalf of a putative class of purchasers of Alkermes securities during the period of July 31, 2014 through November 1, 2018 and alleges violations of Sections 10(b) and 20(a) of the Exchange Act based on allegedly false or misleading statements and omissions regarding the Company’s clinical methodologies and regulatory submission for ALKS 5461 and the FDA’s review and consideration of that submission. The lawsuit seeks, among other things, unspecified money damages, prejudgment and postjudgment interest, reasonable attorneys’ fees, expert fees and other costs. In August 2019, the defendants filed a pre-motion letter (in respect of a requested motion to dismiss filing) with the EDNY District Court and plaintiff filed a response. On November 27, 2019, the defendants served the plaintiff with a motion to dismiss, and on December 27, 2019, the plaintiff served the defendants with its opposition to such motion. On January 17, 2020, the defendants filed the fully-briefed motion, including a reply to the plaintiff’s opposition, with the EDNY District Court. For information about risks relating to this action, see “Item 1A—Risk Factors” in the Annual Report, including the section entitled “—Litigation or arbitration against Alkermes, including securities litigation, or citizen petitions filed with the FDA, may result in financial losses, harm our reputation, divert management resources, negatively impact the approval of our products, or otherwise negatively impact our business.”

Purchase Commitments

The Company has open purchase orders for materials, supplies, services and property, plant and equipment as part of the normal course of business. At December 31, 2019, the Company had open purchase orders totaling $395.3 million and $33.5 million for non-capital and capital commitments, respectively.