Financial Instruments (Details 1) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized cost	$ 2,859.1	$ 2,965.0
Gross unrealized gains	7.3	6.0
Gross unrealized losses	(0.9)	(0.7)
Fair value	2,865.5	2,970.3
Marketable equity securities, fair value	2,865.5	2,970.3
Corporate debt securities Current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	1,282.5	1,057.2
Gross unrealized gains	1.5	1.0
Gross unrealized losses	(0.1)	0.0
Fair value	1,283.9	1,058.2
Corporate debt securities Non-current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	502.8	633.9
Gross unrealized gains	3.8	3.0
Gross unrealized losses	(0.3)	0.0
Fair value	506.3	636.9
Government securities Current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	657.7	502.9
Gross unrealized gains	0.5	0.4
Gross unrealized losses	0.0	0.0
Fair value	658.2	503.3
Government securities Non-current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	307.9	510.1
Gross unrealized gains	0.8	0.8
Gross unrealized losses	(0.1)	(0.3)
Fair value	308.6	510.6
Mortgage and other asset backed securities Current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	0.6	0.7
Gross unrealized gains	0.0	0.0
Gross unrealized losses	0.0	0.0
Fair value	0.6	0.7
Mortgage and other asset backed securities Non-current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	107.6	260.2
Gross unrealized gains	0.7	0.8
Gross unrealized losses	(0.4)	(0.4)
Fair value	107.9	260.6
Marketable equity securities
Debt Securities, Available-for-sale [Line Items]
Marketable equity securities, amortized cost	428.0	218.4
Marketable equity securities, gross unrealized gains	114.6	132.1
Marketable equity securities, gross unrealized losses	(15.6)	(13.0)
Marketable equity securities, fair value	$ 527.0	$ 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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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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