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Financial Instruments (Details 1) - USD ($) $ in Millions | Jun. 30, 2019 | Dec. 31, 2018
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Amortized cost | $ 2,530.4 | $ 3,694.0
Gross unrealized gains | 8.3 | 1.3
Gross unrealized losses | (0.6) | (6.0)
Fair value | 2,538.1 | 3,689.3
Marketable equity securities, fair value | 2,538.1 | 3,689.3
Corporate debt securities Current |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized cost | 933.4 | 1,608.4
Gross unrealized gains | 1.1 | 0.0
Gross unrealized losses | 0.0 | (0.9)
Fair value | 934.5 | 1,607.5
Corporate debt securities Non-current |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized cost | 748.9 | 854.9
Gross unrealized gains | 4.4 | 0.7
Gross unrealized losses | (0.1) | (3.9)
Fair value | 753.2 | 851.7
Government securities Current |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized cost | 293.6 | 706.1
Gross unrealized gains | 0.4 | 0.1
Gross unrealized losses | 0.0 | (0.4)
Fair value | 294.0 | 705.8
Government securities Non-current |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized cost | 309.7 | 264.0
Gross unrealized gains | 0.9 | 0.1
Gross unrealized losses | (0.2) | (0.3)
Fair value | 310.4 | 263.8
Mortgage and other asset backed securities Current |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized cost | 0.3 | 0.1
Gross unrealized gains | 0.0 | 0.0
Gross unrealized losses | 0.0 | 0.0
Fair value | 0.3 | 0.1
Mortgage and other asset backed securities Non-current |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized cost | 244.5 | 260.5
Gross unrealized gains | 1.5 | 0.4
Gross unrealized losses | (0.3) | (0.5)
Fair value | 245.7 | 260.4
Marketable equity securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Marketable equity securities, amortized cost | 229.3 | 496.2
Marketable equity securities, gross unrealized gains | 294.2 | 127.7
Marketable equity securities, gross unrealized losses | (13.5) | (8.5)
Marketable equity securities, fair value | 510.0 | $ 615.4
Other current assets | Marketable equity securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Marketable equity securities, amortized cost | 117.9 |
Marketable equity securities, gross unrealized gains | 46.3 |
Marketable equity securities, gross unrealized losses | 0.0 |
Marketable equity securities, fair value | 164.2 |
Other noncurrent assets | Marketable equity securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Marketable equity securities, amortized cost | 111.4 |
Marketable equity securities, gross unrealized gains | 247.9 |
Marketable equity securities, gross unrealized losses | (13.5) |
Marketable equity securities, fair value | $ 345.8 |

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- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 + Details
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- Definition Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 + Details
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454 + Details
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