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Collaborative and Other Relationships Collaborative and Other Relationships - Collaborations (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Mar. 31, 2019 | Mar. 31, 2018 | Dec. 31, 2018
Eisai |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |
Percentage of future development costs related to Eisai | 45.00% |  | 15.00%
Loss on research and development contracts terminated with Eisai | $ 45.0 |  |
Eisai | BAN2401 and Elenbecestat |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |
Expense incurred by the collaboration | 68.0 | $ 52.2 |
Expense reflected within statements of income | 34.0 | 26.1 |
Skyhawk Therapeutics |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |
Additional milestone payment to Skyhawk | 2,000.0 |  |
Upfront and milestone payments made to collaborative partner | 74.0 |  |
Research and development expense | 38.5 |  |
Prepaid research and development expenses | 35.5 |  |
Research and development | Eisai | Aducanumab |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |
Expense incurred by the collaboration | 162.5 | 63.6 |
Expense reflected within statements of income | 89.4 | 63.6 |
Selling, general and administrative | Eisai | Aducanumab |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |
Expense incurred by the collaboration | 20.9 | 7.1 |
Expense reflected within statements of income | $ 11.6 | $ 3.9 |

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- Definition The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 985 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 730 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6420194&loc=d3e21568-108373 + Details
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