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

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).

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-Topic 320
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-Section 50
-Paragraph 2
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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).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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