Summary of Significant Accounting Policies	6 Months Ended
Jun. 30, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying condensed consolidated financial statements of the Company for the three and six months ended June 30, 2020 and 2019 are unaudited and have been prepared on a basis substantially consistent with the audited financial statements for the year ended December 31, 2019. The year-end condensed consolidated balance sheet data, which is presented for comparative purposes, was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the U.S. (commonly referred to as “GAAP”). In the opinion of management, the condensed consolidated financial statements include all adjustments, which are of a normal recurring nature, that are necessary to state fairly the results of operations for the reported periods. These financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto of the Company, which are contained in the Annual Report. The results of the Company’s operations for any interim period are not necessarily indicative of the results of the Company’s operations for any other interim period or for any full fiscal year. Principles of Consolidation The condensed consolidated financial statements include the accounts of Alkermes plc and its wholly-owned subsidiaries as disclosed in Note 2, Summary of Significant Accounting Policies, in the “Notes to Consolidated Financial Statements” accompanying the Annual Report. Intercompany accounts and transactions have been eliminated. Use of Estimates The preparation of the Company’s condensed consolidated financial statements in accordance with GAAP requires management to make estimates, judgments and assumptions that may affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities. On an ongoing basis, the Company evaluates its estimates, judgments and methodologies, including those related to revenue from contracts with its customers and related allowances, impairment and amortization of intangibles and long-lived assets, share-based compensation, income taxes including the valuation allowance for deferred tax assets, valuation of investments, contingent consideration and litigation. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results may differ from these estimates under different assumptions or conditions. Segment Information The Company operates as one business segment, which is the business of developing, manufacturing and commercializing medicines. The Company’s chief decision maker, the Chief Executive Officer and Chairman of the Company’s board of directors, reviews the Company’s operating results on an aggregate basis and manages the Company’s operations as a single operating unit. Risks and Uncertainties In March 2020, COVID-19 was declared a global pandemic by the World Health Organization. To date, COVID-19 has surfaced in nearly all regions around the world and resulted in travel restrictions and business slowdowns or shutdowns in affected areas. Almost all U.S. states, many local jurisdictions and countries around the world have issued “shelter-in-place” orders, quarantines, executive orders and similar government orders, and recommendations for their residents to control the spread of COVID-19. Such orders, restrictions and recommendations, and the perception that additional orders, restrictions or recommendations could occur, have resulted in widespread closures of businesses, work stoppages, slowdowns and delays, work-from-home policies and travel restrictions, among other effects. Although some local, state and national governments have begun to relax “shelter-in-place” orders, social distancing requirements and other restrictive measures, and while the Company has begun to observe, and expects to continue to observe, a gradual normalization in patient and healthcare provider practices, the impacts and extent of the relaxing of such restrictions and the expected normalization of such practices are not yet known, and it remains difficult to predict the nature and extent of the future impacts that the pandemic will have on the Company’s business. The Company continues to closely monitor and rapidly respond to the ongoing impact of COVID-19 on its employees, communities and business operations. Due to numerous uncertainties surrounding the ongoing COVID-19 pandemic, the Company is unable to predict the extent of the impact that the COVID-19 pandemic may continue to have on the Company’s future financial condition and operating results. These uncertainties include, among other things, the ultimate severity and duration of the pandemic; governmental, business or other actions that have been, or will be, taken in response to the pandemic, including continued restrictions on travel and mobility, business closures and operating restrictions, and imposition of social distancing measures; impacts of the pandemic on the vendors or distribution channels in the Company’s supply chain and on the Company’s ability to continue to manufacture its products; impacts of the pandemic on the conduct of the Company’s clinical trials, including with respect to enrollment rates, availability of investigators and clinical trial sites, and monitoring of data; impacts of the pandemic on healthcare systems that serve people living with opioid dependence, alcohol dependence and schizophrenia; impacts of the pandemic on the regulatory agencies with which the Company interacts in the development, review, approval and commercialization of its medicines; impacts of the pandemic on reimbursement for the Company’s products, including the Company’s Medicaid rebate liability, and for services related to the use of its products; and impacts of the pandemic on the U.S., Irish and global economies more broadly. The Company relies upon third parties for many aspects of its business, including the provision of goods and services related to the manufacture of its clinical products and its, and its partners’, marketed products, the conduct of its clinical trials, and the sale of marketed products from which the Company receives manufacturing and royalty revenue. Any prolonged material disruption to the third parties on which the Company relies could negatively impact the Company’s ability to conduct business in the manner and on the timelines presently planned, which could have a material adverse impact on the Company’s business, results of operations and financial condition. The marketed products from which the Company derives revenue, including manufacturing and royalty revenue, are primarily injectable medications administered by healthcare professionals. Given developments that have transpired to date, and may continue to transpire, in response to the pandemic, including the implementation of “shelter-in-place” policies, social distancing requirements and other restrictive measures, commercial sales of these marketed products have been adversely impacted to varying degrees and the Company expects commercial sales of these marketed products to continue to be adversely impacted while the pandemic persists. As it relates to the Company’s proprietary marketed products, during the three months ended June 30, 2020, the Company saw the commercial impact of the COVID-19 pandemic, particularly with respect to VIVITROL units sold, which decreased 9% compared to the three months ended March 31, 2020. This decrease was primarily due to the impacts of COVID-19 on patient practices and COVID-19-related limitations on access to healthcare provider facilities where VIVITROL could be administered and related services could be provided. ARISTADA gross sales during the three months ended June 30, 2020 increased 11% compared to the three months ended March 31, 2020, despite COVID-19-related impacts on access to healthcare provider facilities and patient flow. During the three months ended June 30, 2020, the Company took actions to support uninterrupted access to its proprietary marketed products, including through expansion of its injection-site network, and in June, began to see some stabilization in VIVITROL units sold; however, the Company currently expects commercial sales of its marketed products, particularly VIVITROL, to continue to be impacted by the COVID-19 pandemic over the next few quarters, including, for VIVITROL, as a result of the impact that the decrease in patient volume during the three months ended June 30, 2020 is expected to have on overall unit demand in the second half of 2020. The Company continues to operate its manufacturing facilities and supply its medicines. While the Company continues to conduct R&D activities, including its ongoing clinical trials, the COVID-19 pandemic has impacted, and may continue to impact, the timelines of certain of its early-stage discovery efforts and clinical trials. The Company is working with its internal teams, its clinical investigators, R&D vendors and critical supply chain vendors to continually assess, and mitigate, any potential adverse impacts of COVID-19 on its manufacturing operations and R&D activities. Despite disruptions to the Company’s business operations and the business operations of third parties on which it relies, the COVID-19 pandemic has not significantly impacted the Company’s operating results and financial condition to date, except with relation to net sales of VIVITROL, as noted above. These items are discussed in greater detail later in the “Results of Operations” section in “Part I, Item 2—Management’s Discussion and Analysis of Financial Condition and Results of Operations” in this Form 10-Q. New Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard-setting bodies that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. In June 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-13, Measurement of Credit Losses on Financial Instruments, to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. To achieve this objective, the amendments in this ASU replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. This standard primarily impacts how firms account for credit losses and requires an impairment model, known as the current expected credit loss model, that is based on expected losses rather than incurred losses. Companies are required to carry an allowance for expected credit losses for most debt instruments (except those carried at fair value), trade receivables, lease receivables, reinsurance receivables, financial guarantee contracts and loan commitments. For available-for-sale debt securities with unrealized losses, the standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. The standard limits the amount of credit losses to be recognized for available-for-sale debt securities to the amount by which the carrying value exceeds fair value and requires the reversal of previous recognized credit losses if fair value increases. The Company’s investment portfolio primarily consists of available-for-sale securities carried at fair value. Further, the Company’s trade receivables do not have abnormally long terms and the Company has historically rarely written off trade receivables. The Company adopted this standard on January 1, 2020 and the adoption of this standard did not have a material impact on the Company’s consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement, which aims to improve the effectiveness of fair value measurement disclosures. The amendments in this ASU modify the disclosure requirements on fair value measurements based on the concepts in FASB Concepts Statement, Conceptual Framework for Financial Reporting - Chapter 8: Notes to Financial Statements, including the consideration of costs and benefits. The Company adopted this standard on January 1, 2020 and the adoption of this standard had no impact on the Company’s financial statement disclosures. In August 2018, the FASB issued ASU 2018-15, Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract, which aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). This ASU also requires the entity to expense the capitalized implementation costs of a hosting arrangement that is a service contract over the term of the hosting arrangement, which includes reasonably certain renewals. The Company adopted this standard on January 1, 2020 using the prospective transition method, whereby it applied the requirements to any eligible costs incurred after adoption. The Company has not incurred any material eligible costs during the six months ended June 30, 2020. In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes, which simplifies the accounting for income taxes by removing certain exceptions to the general principles of Accounting Standards Codification (“ASC”) 740, Income Taxes (“Topic 740”). The amendments also improve consistent application of, and simplify, GAAP for other areas of Topic 740 by clarifying and amending existing guidance. The Company adopted this standard on January 1, 2020 and the adoption of this standard had no material impact on the Company’s consolidated financial statements. In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform, which provides optional guidance for a limited period of time to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform on financial reporting. This amendment applies to all entities, subject to meeting certain criteria, that have contracts, hedging relationships, and other transactions that reference LIBOR or another reference rate expected to be discontinued because of reference rate reform. This ASU became effective immediately and may be applied prospectively to contract modifications made and hedging relationships entered into or evaluated on or before December 31, 2022. The Company is currently assessing the impact that this ASU will have on its consolidated financial statements.

Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2020

Summary of Significant Accounting Policies

2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Presentation

The accompanying condensed consolidated financial statements of the Company for the three and six months ended June 30, 2020 and 2019 are unaudited and have been prepared on a basis substantially consistent with the audited financial statements for the year ended December 31, 2019. The year-end condensed consolidated balance sheet data, which is presented for comparative purposes, was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the U.S. (commonly referred to as “GAAP”). In the opinion of management, the condensed consolidated financial statements include all adjustments, which are of a normal recurring nature, that are necessary to state fairly the results of operations for the reported periods.

These financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto of the Company, which are contained in the Annual Report. The results of the Company’s operations for any interim period are not necessarily indicative of the results of the Company’s operations for any other interim period or for any full fiscal year.

Principles of Consolidation

The condensed consolidated financial statements include the accounts of Alkermes plc and its wholly-owned subsidiaries as disclosed in Note 2, Summary of Significant Accounting Policies, in the “Notes to Consolidated Financial Statements” accompanying the Annual Report. Intercompany accounts and transactions have been eliminated.

Use of Estimates

The preparation of the Company’s condensed consolidated financial statements in accordance with GAAP requires management to make estimates, judgments and assumptions that may affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities. On an ongoing basis, the Company evaluates its estimates, judgments and methodologies, including those related to revenue from contracts with its customers and related allowances, impairment and amortization of intangibles and long-lived assets, share-based compensation, income taxes including the valuation allowance for deferred tax assets, valuation of investments, contingent consideration and litigation. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results may differ from these estimates under different assumptions or conditions.

Segment Information

The Company operates as one business segment, which is the business of developing, manufacturing and commercializing medicines. The Company’s chief decision maker, the Chief Executive Officer and Chairman of the Company’s board of directors, reviews the Company’s operating results on an aggregate basis and manages the Company’s operations as a single operating unit.

Risks and Uncertainties

In March 2020, COVID-19 was declared a global pandemic by the World Health Organization. To date, COVID-19 has surfaced in nearly all regions around the world and resulted in travel restrictions and business slowdowns or shutdowns in affected areas. Almost all U.S. states, many local jurisdictions and countries around the world have issued “shelter-in-place” orders, quarantines, executive orders and similar government orders, and recommendations for their residents to control the spread of COVID-19. Such orders, restrictions and recommendations, and the perception that additional orders, restrictions or recommendations could occur, have resulted in widespread closures of businesses, work stoppages, slowdowns and delays, work-from-home policies and travel restrictions, among other effects. Although some local, state and national governments have begun to relax “shelter-in-place” orders, social distancing requirements and other restrictive measures, and while the Company has begun to observe, and expects to continue to observe, a gradual normalization in patient and healthcare provider practices, the impacts and extent of the relaxing of such restrictions and the expected normalization of such practices are not yet known, and it remains difficult to predict the nature and extent of the future impacts that the pandemic will have on the Company’s business.

The Company continues to closely monitor and rapidly respond to the ongoing impact of COVID-19 on its employees, communities and business operations. Due to numerous uncertainties surrounding the ongoing COVID-19 pandemic, the Company is unable to predict the extent of the impact that the COVID-19 pandemic may continue to have on the Company’s future financial condition and operating results. These uncertainties include, among other things, the ultimate severity and duration of the pandemic; governmental, business or other actions that have been, or will be, taken in response to the pandemic, including continued restrictions on travel and mobility, business closures and operating restrictions, and imposition of social distancing measures; impacts of the pandemic on the vendors or distribution channels in the Company’s supply chain and on the Company’s ability to continue to manufacture its products; impacts of the pandemic on the conduct of the Company’s clinical trials, including with respect to enrollment rates, availability of investigators and clinical trial sites, and monitoring of data; impacts of the pandemic on healthcare systems that serve people living with opioid dependence, alcohol dependence and schizophrenia; impacts of the pandemic on the regulatory agencies with which the Company interacts in the development, review, approval and commercialization of its medicines; impacts of the pandemic on reimbursement for the Company’s products, including the Company’s Medicaid rebate liability, and for services related to the use of its products; and impacts of the pandemic on the U.S., Irish and global economies more broadly.

The Company relies upon third parties for many aspects of its business, including the provision of goods and services related to the manufacture of its clinical products and its, and its partners’, marketed products, the conduct of its clinical trials, and the sale of marketed products from which the Company receives manufacturing and royalty revenue. Any prolonged material disruption to the third parties on which the Company relies could negatively impact the Company’s ability to conduct business in the manner and on the timelines presently planned, which could have a material adverse impact on the Company’s business, results of operations and financial condition.

The marketed products from which the Company derives revenue, including manufacturing and royalty revenue, are primarily injectable medications administered by healthcare professionals. Given developments that have transpired to date, and may continue to transpire, in response to the pandemic, including the implementation of “shelter-in-place” policies, social distancing requirements and other restrictive measures, commercial sales of these marketed products have been adversely impacted to varying degrees and the Company expects commercial sales of these marketed products to continue to be adversely impacted while the pandemic persists.

As it relates to the Company’s proprietary marketed products, during the three months ended June 30, 2020, the Company saw the commercial impact of the COVID-19 pandemic, particularly with respect to VIVITROL units sold, which decreased 9% compared to the three months ended March 31, 2020. This decrease was primarily due to the impacts of COVID-19 on patient practices and COVID-19-related limitations on access to healthcare provider facilities where VIVITROL could be administered and related services could be provided. ARISTADA gross sales during the three months ended June 30, 2020 increased 11% compared to the three months ended March 31, 2020, despite COVID-19-related impacts on access to healthcare provider facilities and patient flow. During the three months ended June 30, 2020, the Company took actions to support uninterrupted access to its proprietary marketed products, including through expansion of its injection-site network, and in June, began to see some stabilization in VIVITROL units sold; however, the Company currently expects commercial sales of its marketed products, particularly VIVITROL, to continue to be impacted by the COVID-19 pandemic over the next few quarters, including, for VIVITROL, as a result of the impact that the decrease in patient volume during the three months ended June 30, 2020 is expected to have on overall unit demand in the second half of 2020.

The Company continues to operate its manufacturing facilities and supply its medicines. While the Company continues to conduct R&D activities, including its ongoing clinical trials, the COVID-19 pandemic has impacted, and may continue to impact, the timelines of certain of its early-stage discovery efforts and clinical trials. The Company is working with its internal teams, its clinical investigators, R&D vendors and critical supply chain vendors to continually assess, and mitigate, any potential adverse impacts of COVID-19 on its manufacturing operations and R&D activities.

Despite disruptions to the Company’s business operations and the business operations of third parties on which it relies, the COVID-19 pandemic has not significantly impacted the Company’s operating results and financial condition to date, except with relation to net sales of VIVITROL, as noted above. These items are discussed in greater detail later in the “Results of Operations” section in “Part I, Item 2—Management’s Discussion and Analysis of Financial Condition and Results of Operations” in this Form 10-Q.

New Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard-setting bodies that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption.

In June 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-13, Measurement of Credit Losses on Financial Instruments, to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. To achieve this objective, the amendments in this ASU replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. This standard primarily impacts how firms account for credit losses and requires an impairment model, known as the current expected credit loss model, that is based on expected losses rather than incurred losses. Companies are required to carry an allowance for expected credit losses for most debt instruments (except those carried at fair value), trade receivables, lease receivables, reinsurance receivables, financial guarantee contracts and loan commitments. For available-for-sale debt securities with unrealized losses, the standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. The standard limits the amount of credit losses to be recognized for available-for-sale debt securities to the amount by which the carrying value exceeds fair value and requires the reversal of previous recognized credit losses if fair value increases. The Company’s investment portfolio primarily consists of available-for-sale securities carried at fair value. Further, the Company’s trade receivables do not have abnormally long terms and the Company has historically rarely written off trade receivables. The Company adopted this standard on January 1, 2020 and the adoption of this standard did not have a material impact on the Company’s consolidated financial statements.

In August 2018, the FASB issued ASU 2018-13, Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement, which aims to improve the effectiveness of fair value measurement disclosures. The amendments in this ASU modify the disclosure requirements on fair value measurements based on the concepts in FASB Concepts Statement, Conceptual Framework for Financial Reporting - Chapter 8: Notes to Financial Statements,

including the consideration of costs and benefits. The Company adopted this standard on January 1, 2020 and the adoption of this standard had no impact on the Company’s financial statement disclosures.

In August 2018, the FASB issued ASU 2018-15, Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract, which aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). This ASU also requires the entity to expense the capitalized implementation costs of a hosting arrangement that is a service contract over the term of the hosting arrangement, which includes reasonably certain renewals. The Company adopted this standard on January 1, 2020 using the prospective transition method, whereby it applied the requirements to any eligible costs incurred after adoption. The Company has not incurred any material eligible costs during the six months ended June 30, 2020.

In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes, which simplifies the accounting for income taxes by removing certain exceptions to the general principles of Accounting Standards Codification (“ASC”) 740, Income Taxes (“Topic 740”). The amendments also improve consistent application of, and simplify, GAAP for other areas of Topic 740 by clarifying and amending existing guidance. The Company adopted this standard on January 1, 2020 and the adoption of this standard had no material impact on the Company’s consolidated financial statements.

In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform, which provides optional guidance for a limited period of time to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform on financial reporting. This amendment applies to all entities, subject to meeting certain criteria, that have contracts, hedging relationships, and other transactions that reference LIBOR or another reference rate expected to be discontinued because of reference rate reform. This ASU became effective immediately and may be applied prospectively to contract modifications made and hedging relationships entered into or evaluated on or before December 31, 2022. The Company is currently assessing the impact that this ASU will have on its consolidated financial statements.