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Financial Instruments (Details 1) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Marketable Debt and Equity Securities
Fair Value	$ 3,689.3	$ 5,172.5
Gross Unrealized Gains	1.3	2.3
Gross Unrealized Losses	(6.0)	(2.8)
Amortized Cost	3,694.0	5,173.0
Corporate debt securities Current
Marketable Debt and Equity Securities
Fair Value	1,607.5	1,039.3
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(0.9)	(0.2)
Amortized Cost	1,608.4	1,039.5
Corporate debt securities Non-current
Marketable Debt and Equity Securities
Fair Value	851.7	1,570.5
Gross Unrealized Gains	0.7	0.9
Gross Unrealized Losses	(3.9)	0.0
Amortized Cost	854.9	1,569.6
Government securities Current
Marketable Debt and Equity Securities
Fair Value	705.8	1,075.1
Gross Unrealized Gains	0.1	0.1
Gross Unrealized Losses	(0.4)	(0.7)
Amortized Cost	706.1	1,075.7
Government securities Non-current
Marketable Debt and Equity Securities
Fair Value	263.8	844.2
Gross Unrealized Gains	0.1	0.2
Gross Unrealized Losses	(0.3)	(1.1)
Amortized Cost	264.0	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	260.4	642.6
Gross Unrealized Gains	0.4	1.1
Gross Unrealized Losses	(0.5)	(0.8)
Amortized Cost	260.5	642.3
Marketable equity securities
Marketable Debt and Equity Securities
Fair Value	615.4	11.8
Gross Unrealized Gains	127.7	1.8
Gross Unrealized Losses	(8.5)	(4.4)
Amortized Cost	$ 496.2	$ 14.4

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- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as 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=82897076&loc=d3e27161-111563

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