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Collaborative and Other Relationships - Equity Method Investments (Details) $ in Millions, ₩ in Billions | 3 Months Ended | 6 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Jun. 30, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2018 KRW (₩) | Jun. 30, 2018 USD ($) | Jun. 30, 2019 USD ($) | Jun. 30, 2018 USD ($) | Jun. 30, 2019 KRW (₩) | Dec. 31, 2018 KRW (₩) | Nov. 07, 2018 USD ($) | Sep. 30, 2018
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Our share of Samsung Bioepis gains (losses) | $ 16.3 |  |  | $ 0.0 | $ 45.0 | $ 0.0 |  |  |  |
Collaboration profit (loss) sharing | 63.5 |  |  | 39.2 | 121.6 | 81.7 |  |  |  |
Total revenues | $ 3,616.7 |  |  | 3,356.5 | $ 7,106.5 | 6,487.6 |  |  |  |
Samsung Bioepis |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Percentage of stake in entity |  |  |  |  |  |  |  |  |  | 5.00%
Percentage of stake in entity maximum | 49.90% |  |  |  | 49.90% |  | 49.90% |  |  |
Payments to acquire additional investment in equity method investment |  | $ 676.6 | ₩ 759.5 |  |  |  |  |  |  |
Amortization of basis differences |  |  |  |  |  |  |  |  | $ 675.0 |
Loss recorded on Samsung Bioepis joint venture | $ 16.3 |  |  |  | $ 45.0 |  |  |  |  |
Our share of Samsung Bioepis gains (losses) | (5.5) |  |  |  | 8.5 |  |  |  |  |
Amortization of basis differences | 21.8 |  |  |  | 36.5 |  |  |  |  |
Investment in Samsung Bioepis | 615.5 | $ 680.6 |  |  | $ 615.5 |  | ₩ 712.8 | ₩ 759.5 |  |
Biogen share of co-promotion profits or losses |  |  |  |  | 50.00% |  |  |  |  |
Collaboration profit (loss) sharing | 63.4 |  |  | 39.7 | $ 121.5 | 83.5 |  |  |  |
Collaborative arrangement | Samsung Bioepis |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Total revenues | $ 52.2 |  |  | $ 14.7 | $ 77.0 | $ 32.6 |  |  |  |
Inventory | Samsung Bioepis |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Amortization of basis differences |  |  |  |  |  |  |  |  | 115.0 |
Equity method investment basis difference amortization period |  |  |  |  | 1 year 6 months |  |  |  |  |
Developed technology | Samsung Bioepis |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Amortization of basis differences |  |  |  |  |  |  |  |  | 615.0 |
Equity method investment basis difference amortization period |  |  |  |  | 15 years |  |  |  |  |
In Process Research and Development | Samsung Bioepis |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Amortization of basis differences |  |  |  |  |  |  |  |  | 170.0 |
Deferred tax liability | Samsung Bioepis |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Amortization of basis differences |  |  |  |  |  |  |  |  | $ 225.0 |

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- Definition The cash outflow associated with the purchase of or advances to an equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence. + 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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