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Financial Instruments (Details 1) - USD ($) $ in Millions | Mar. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Marketable Debt and Equity Securities |  |
Fair Value | $ 3,008.2 | $ 5,172.5
Gross Unrealized Gains | 0.5 | 2.3
Gross Unrealized Losses | (3.3) | (2.8)
Amortized Cost | 3,011.0 | 5,173.0
Corporate debt securities Current |  |
Marketable Debt and Equity Securities |  |
Fair Value | 912.9 | 1,039.3
Gross Unrealized Gains | 0.0 | 0.0
Gross Unrealized Losses | (0.8) | (0.2)
Amortized Cost | 913.7 | 1,039.5
Corporate debt securities Non-current |  |
Marketable Debt and Equity Securities |  |
Fair Value | 645.0 | 1,570.5
Gross Unrealized Gains | 0.3 | 0.9
Gross Unrealized Losses | (0.7) | 0.0
Amortized Cost | 645.4 | 1,569.6
Government securities Current |  |
Marketable Debt and Equity Securities |  |
Fair Value | 895.0 | 1,075.1
Gross Unrealized Gains | 0.0 | 0.1
Gross Unrealized Losses | (0.5) | (0.7)
Amortized Cost | 895.5 | 1,075.7
Government securities Non-current |  |
Marketable Debt and Equity Securities |  |
Fair Value | 248.2 | 844.2
Gross Unrealized Gains | 0.1 | 0.2
Gross Unrealized Losses | (0.3) | (1.1)
Amortized Cost | 248.4 | 845.1
Mortgage and other asset backed securities Current |  |
Marketable Debt and Equity Securities |  |
Fair Value | 0.1 | 0.8
Gross Unrealized Gains | 0.0 | 0.0
Gross Unrealized Losses | 0.0 | 0.0
Amortized Cost | 0.1 | 0.8
Mortgage and other asset backed securities Non-current |  |
Marketable Debt and Equity Securities |  |
Fair Value | 307.0 | 642.6
Gross Unrealized Gains | 0.1 | 1.1
Gross Unrealized Losses | (1.0) | (0.8)
Amortized Cost | $ 307.9 | 642.3
Marketable equity securities |  |
Marketable Debt and Equity Securities |  |
Fair Value |  | 11.8
Gross Unrealized Gains |  | 1.8
Gross Unrealized Losses |  | (4.4)
Amortized Cost |  | $ 14.4

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