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Business Acquisition (Details Textual) $ / shares in Units, $ in Millions | 1 Months Ended | 3 Months Ended | 6 Months Ended |
--- | --- | --- | --- | ---
Mar. 31, 2020 USD ($) | Jun. 30, 2019 Assets | Jun. 30, 2020 USD ($) | Jun. 30, 2019 USD ($) | Jun. 30, 2020 USD ($) | Jun. 30, 2019 USD ($) | Jun. 07, 2019 USD ($) $ / shares
Business Acquisition [Line Items] |  |  |  |  |  |  |
Acquired in-process research and development |  |  | $ 0.0 | $ 0.0 | $ 75.0 | $ 0.0 |
Clinical Assets Acquired | Assets |  | 2 |  |  |  |  |
BIIB118 |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Acquired in-process research and development | $ 75.0 |  |  |  |  |  |
Estimated additional payments upon achievement of development and commercial milestones | $ 635.0 |  |  |  |  |  |
Nightstar |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Price per share | $ / shares |  |  |  |  |  |  | $ 25.50
Total transaction value |  |  |  | 847.6 |  |  |
Payments for pre-combination equity compensation |  |  |  | 4.6 |  |  |
In-process research and development |  |  |  |  |  |  | $ 700.0
Selling, general and administrative | Nightstar |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Fair value of post-combination equity compensation |  |  |  | 18.4 |  |  |
Research and development | Nightstar |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Fair value of post-combination equity compensation |  |  |  | 7.8 |  |  |
Post-acquisition equity compensation | Nightstar |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Fair value of post-combination equity compensation |  |  |  | $ 26.2 |  |  |

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- Definition Estimated additional payments upon achievement of development and commercial milestones. + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination. + References No definition available. + Details
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- Definition Amount of assets, excluding financial assets and goodwill, that lack physical substance, having a projected indefinite period of benefit, acquired at the acquisition date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=116869197&loc=d3e4845-128472 + Details
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- Definition The cash outflow associated with other payments to acquire businesses including deposit on pending acquisitions and preacquisition costs. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585 + Details
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