Financial Instruments (Details 1) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Marketable Debt and Equity Securities
Fair Value	$ 5,398.0	$ 4,880.9
Gross Unrealized Gains	2.9	0.3
Gross Unrealized Losses	(11.2)	(10.6)
Amortized Cost	5,406.3	4,891.2
Corporate debt securities Current
Marketable Debt and Equity Securities
Fair Value	1,408.6	394.3
Gross Unrealized Gains	0.2	0.0
Gross Unrealized Losses	(0.6)	(0.5)
Amortized Cost	1,409.0	394.8
Corporate debt securities Non-current
Marketable Debt and Equity Securities
Fair Value	1,255.2	1,116.6
Gross Unrealized Gains	1.2	0.1
Gross Unrealized Losses	(4.7)	(4.1)
Amortized Cost	1,258.7	1,120.6
Government securities Current
Marketable Debt and Equity Securities
Fair Value	1,156.0	1,723.4
Gross Unrealized Gains	0.2	0.1
Gross Unrealized Losses	(0.3)	(1.1)
Amortized Cost	1,156.1	1,724.4
Government securities Non-current
Marketable Debt and Equity Securities
Fair Value	1,016.5	1,152.5
Gross Unrealized Gains	0.5	0.0
Gross Unrealized Losses	(3.4)	(3.1)
Amortized Cost	1,019.4	1,155.6
Mortgage and other asset backed securities Current
Marketable Debt and Equity Securities
Fair Value	4.0	2.8
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	0.0
Amortized Cost	4.0	2.8
Mortgage and other asset backed securities Non-current
Marketable Debt and Equity Securities
Fair Value	557.7	491.3
Gross Unrealized Gains	0.8	0.1
Gross Unrealized Losses	(2.2)	(1.8)
Amortized Cost	559.1	493.0
Marketable equity securities
Marketable Debt and Equity Securities
Fair Value	24.9	37.5
Gross Unrealized Gains	0.7	9.2
Gross Unrealized Losses	(9.3)	0.0
Amortized Cost	$ 33.5	$ 28.3

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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