Financial Instruments (Details 1) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized cost	$ 2,247.0	$ 2,965.0
Gross unrealized gains	7.7	6.0
Gross unrealized losses	(16.1)	(0.7)
Fair value	2,238.6	2,970.3
Marketable equity securities, fair value	2,238.6	2,970.3
Corporate debt securities Current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	923.8	1,057.2
Gross unrealized gains	0.2	1.0
Gross unrealized losses	(2.2)	0.0
Fair value	921.8	1,058.2
Corporate debt securities Non-current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	442.7	633.9
Gross unrealized gains	0.6	3.0
Gross unrealized losses	(11.6)	0.0
Fair value	431.7	636.9
Government securities Current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	343.2	502.9
Gross unrealized gains	3.4	0.4
Gross unrealized losses	0.0	0.0
Fair value	346.6	503.3
Government securities Non-current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	361.5	510.1
Gross unrealized gains	2.5	0.8
Gross unrealized losses	(0.2)	(0.3)
Fair value	363.8	510.6
Mortgage and other asset backed securities Current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	0.7	0.7
Gross unrealized gains	0.0	0.0
Gross unrealized losses	0.0	0.0
Fair value	0.7	0.7
Mortgage and other asset backed securities Non-current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	175.1	260.2
Gross unrealized gains	1.0	0.8
Gross unrealized losses	(2.1)	(0.4)
Fair value	174.0	260.6
Marketable equity securities
Debt Securities, Available-for-sale [Line Items]
Marketable equity securities, amortized cost	286.2	218.4
Marketable equity securities, gross unrealized gains	6.5	132.1
Marketable equity securities, gross unrealized losses	(16.6)	(13.0)
Marketable equity securities, fair value	$ 276.1	$ 337.5

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
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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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