Business	3 Months Ended
Business	Mar. 31, 2021
Business [Abstract]
Business	Business Business Alexion Pharmaceuticals, Inc. (Alexion, the Company, we, our or us) is a global biopharmaceutical company focused on serving patients and families affected by rare diseases and devastating conditions through the discovery, development and commercialization of life-changing medicines. As a leader in rare diseases for more than 25 years, Alexion has developed and commercializes two approved complement inhibitors to treat patients with paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS), as well as the first and only approved complement inhibitor to treat anti-acetylcholine receptor (AChR) antibody-positive generalized myasthenia gravis (gMG) and neuromyelitis optica spectrum disorder (NMOSD) in patients who are anti-aquaporin-4 (AQP4) antibody positive. Alexion also has two highly innovative enzyme replacement therapies and the first and only approved therapies for patients with life-threatening and ultra-rare metabolic disorders, hypophosphatasia (HPP) and lysosomal acid lipase deficiency (LAL-D) as well as the first and only approved Factor Xa inhibitor reversal agent for patients treated with rivaroxaban or apixaban when reversal of anticoagulation is needed due to life-threatening or uncontrolled bleeding. In addition to our marketed therapies, we have a diverse pipeline resulting from internal innovation and business development. Alexion focuses its research efforts on novel molecules and targets in the complement cascade and its development efforts on the core therapeutic areas of hematology, nephrology, neurology, metabolic disorders, cardiology, ophthalmology and acute care. We were incorporated in 1992 under the laws of the State of Delaware. Merger Agreement with AstraZeneca On December 12, 2020, we entered into an Agreement and Plan of Merger (the Merger Agreement) with AstraZeneca PLC, a public limited company incorporated under the laws of England and Wales (AstraZeneca), Delta Omega Sub Holdings Inc., a Delaware corporation and a wholly owned subsidiary of AstraZeneca (Bidco), Delta Omega Sub Holdings Inc. 1, a Delaware corporation and a direct, wholly owned subsidiary of Bidco (Merger Sub I) and Delta Omega Sub Holdings LLC 2, a Delaware limited liability company and a direct, wholly owned subsidiary of Bidco (Merger Sub II). The Merger Agreement provides, among other things, that subject to the satisfaction or waiver of the conditions set forth therein (1) Merger Sub I will merge with and into Alexion (the “First Merger”), with Alexion surviving the First Merger as a wholly owned subsidiary of Bidco, and (2) immediately following the effective time of the First Merger (the Effective Time), Alexion will merge with and into Merger Sub II (the Second Merger and, together with the First Merger, the Mergers), with Merger Sub II surviving the Second Merger as a wholly owned subsidiary of Bidco and an indirect wholly owned subsidiary of AstraZeneca. Under the Merger Agreement, at the Effective Time (as defined in the Merger Agreement), each share of common stock, par value $0.0001 per share, of Alexion issued and outstanding immediately prior to the Effective Time (other than certain excluded shares as described in the Merger Agreement) will be converted into the right to receive (1) 2.1243 American depositary shares of AstraZeneca (or, at the election of the holder thereof, a number of ordinary shares of AstraZeneca equal to the number of underlying ordinary shares represented by such American depositary shares) and (2) $60.00 in cash, without interest (collectively, the Merger Consideration). The boards of directors of both companies have unanimously approved the acquisition. The respective obligations of Alexion and AstraZeneca to consummate the transactions contemplated by the Merger Agreement are subject to the satisfaction or waiver of a number of customary conditions, including: (1) the adoption of the Merger Agreement by Alexion’s stockholders; (2) approval of the transactions contemplated by the Merger Agreement by AstraZeneca’s shareholders; (3) the absence of any law or order prohibiting consummation of the Mergers; (4) AstraZeneca’s registration statement on Form F-4 having been declared effective by the Securities and Exchange Commission; (5) AstraZeneca’s shareholder circular (or, if required, prospectus) having been approved by the U.K. Financial Conduct Authority; (6) the American depository shares of AstraZeneca issuable in the Mergers (and the ordinary shares of AstraZeneca represented thereby) having been approved for listing on the Nasdaq; (7) the expiration or early termination of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, and the approval of the Mergers under the antitrust and foreign investment laws of other specified jurisdictions; (8) accuracy of the other party’s representations and warranties, subject to certain materiality standards set forth in the Merger Agreement and (9) compliance by the other party in all material respects with such other party’s obligations under the Merger Agreement. Without limiting the generality of the foregoing, we are subject to a variety of specified restrictions under the Merger Agreement. Unless we obtain AstraZeneca’s prior written consent (which consent may not be unreasonably withheld, conditioned or delayed) and except (i) as required or expressly contemplated by the Merger Agreement, (ii) as required by applicable law or (iii) as set forth in the confidential disclosure schedule delivered by Alexion to AstraZeneca, we may not, among other things and subject to certain exceptions and aggregate limitations, incur additional indebtedness, issue additional shares of our common stock outside of our equity incentive plans, repurchase our common stock, pay dividends, acquire assets, securities or property, dispose of businesses or assets, enter into material contracts or make certain additional capital expenditures. Under the Merger Agreement, Alexion will be required to make a payment to AstraZeneca equal to $1,180.0 if the Merger Agreement is terminated in certain circumstances, including because the Alexion board of directors has changed its recommendation in favor of the Mergers or we terminated the Merger Agreement in order to enter into an agreement providing for a Company Superior Proposal (as defined in the Merger Agreement), and Alexion will be required to make a payment to AstraZeneca equal to $270.0 if the Merger Agreement is terminated because Alexion’s stockholders fail to adopt the Merger Agreement. AstraZeneca will be required to make a payment to Alexion equal to $1,415.0 if the Merger Agreement is terminated in certain circumstances, including because the AstraZeneca board of directors has changed its recommendation in favor of the Mergers or because AstraZeneca’s shareholders fail to approve the transactions contemplated by the Merger Agreement. The acquisition is expected to close during the third quarter 2021.