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Other Consolidated Financial Statement Detail (Details Textual) € in Millions, $ in Millions | 1 Months Ended | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | ---
Feb. 28, 2015 USD ($) | Dec. 31, 2017 USD ($) | Sep. 30, 2017 USD ($) | Jun. 30, 2017 USD ($) | Mar. 31, 2017 USD ($) | Mar. 31, 2017 EUR (€) | Dec. 31, 2016 USD ($) | Sep. 30, 2016 USD ($) | Jun. 30, 2016 USD ($) | Mar. 31, 2016 USD ($) | Jun. 30, 2014 USD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Jun. 30, 2013 USD ($) | Jun. 30, 2013 EUR (€) | Dec. 31, 2011 EUR (€)
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase to goodwill |  |  |  |  |  |  |  |  |  |  |  | $ 1,267.3 | $ 1,026.9 |  |  |  |
Accrued construction in progress |  | $ 159.7 |  |  |  |  | $ 134.0 |  |  |  |  | 159.7 | 134.0 |  |  |  |
TECFIDERA litigation settlement charge |  |  |  |  |  |  | 454.8 |  |  |  |  | 0.0 | 454.8 | $ 0.0 |  |  |
Net charge upon extinguishment of debt |  | 5.2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Prepaid taxes |  | 657.6 |  |  |  |  | 817.0 |  |  |  |  | 657.6 | 817.0 |  |  |  |
Net impairment on certain tax assets |  | 48.8 |  |  |  |  |  |  |  |  |  | 48.8 |  |  |  |  |
Loss contingency, adjustment related to claim amount, percent |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50.00% | 50.00% |
Product, net |  | 2,712.4 | $ 2,622.5 | $ 2,639.7 | $ 2,380.1 |  | 2,502.9 | $ 2,539.6 | $ 2,466.0 | $ 2,309.4 |  | 10,354.7 | 9,817.9 | 9,188.5 |  |  |
Solothurn |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accrued construction in progress |  | 150.0 |  |  |  |  | $ 100.0 |  |  |  |  | 150.0 | 100.0 |  |  |  |
Convergence Pharmaceuticals |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration obligation | $ 274.5 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
TECFIDERA |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Product, net |  |  |  |  |  |  |  |  |  |  |  | 4,214.0 | 3,968.1 | $ 3,638.4 |  |  |
TECFIDERA | Fumapharm AG |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase to goodwill |  |  |  |  |  |  |  |  |  |  |  | 1,500.0 | $ 1,200.0 |  |  |  |
TECFIDERA | Fifteen billion | Fumapharm AG |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cumulative sales level |  | 15,000.0 |  |  |  |  |  |  |  |  |  | 15,000.0 |  |  |  |  |
TECFIDERA | Sixteen billion | Fumapharm AG |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase to goodwill |  | 600.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cumulative sales level |  | $ 16,000.0 |  |  |  |  |  |  |  |  |  | $ 16,000.0 |  |  |  |  |
ITALY |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proposed settlement | € |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | € (33.3) | € (30.7)
Reimbursement Limit Stated In Resolution |  |  |  |  |  |  |  |  |  |  | 24 months |  |  |  |  |  |
Loss contingency accrual |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 15.4 |  |
Product, net |  |  |  |  | $ 45.0 | € 41.8 |  |  |  |  | $ 53.5 |  |  |  |  |  |

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