Financial Instruments (Details 1) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized cost	$ 2,140.9	$ 2,049.1
Gross unrealized gains	1.6	2.3
Gross unrealized losses	(0.6)	(0.4)
Fair value	2,141.9	2,051.0
Marketable equity securities, fair value	2,141.9	2,051.0
Equity Securities, FV-NI, Cost		1,239.5
Equity Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax		749.7
Equity Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, Before Tax		(14.9)
Equity Securities, FV-NI		1,974.3
Corporate debt securities Current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	979.7	897.8
Gross unrealized gains	0.2	0.4
Gross unrealized losses	(0.4)	(0.2)
Fair value	979.5	898.0
Corporate debt securities Non-current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	356.0	402.5
Gross unrealized gains	0.8	1.1
Gross unrealized losses	(0.1)	(0.1)
Fair value	356.7	403.5
Government securities Current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	340.5	380.6
Gross unrealized gains	0.0	0.1
Gross unrealized losses	0.0	0.0
Fair value	340.5	380.7
Government securities Non-current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	336.5	245.9
Gross unrealized gains	0.4	0.5
Gross unrealized losses	0.0	0.0
Fair value	336.9	246.4
Mortgage and other asset backed securities Current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	0.0	0.2
Gross unrealized gains	0.0	0.0
Gross unrealized losses	0.0	0.0
Fair value	0.0	0.2
Mortgage and other asset backed securities Non-current
Debt Securities, Available-for-sale [Line Items]
Amortized cost	128.2	122.1
Gross unrealized gains	0.2	0.2
Gross unrealized losses	(0.1)	(0.1)
Fair value	128.3	122.2
Equity Securities, Current
Debt Securities, Available-for-sale [Line Items]
Equity Securities, FV-NI, Cost	1,168.9	70.6
Equity Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	351.0	15.9
Equity Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, Before Tax	(77.1)	0.0
Equity Securities, FV-NI	1,442.8	86.5
Equity Securities, Non-Current
Debt Securities, Available-for-sale [Line Items]
Equity Securities, FV-NI, Cost	1,168.9	1,168.9
Equity Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	351.0	733.8
Equity Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, Before Tax	(77.1)	(14.9)
Equity Securities, FV-NI	$ 1,442.8	$ 1,887.8

Equity Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax

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Equity Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, Before Tax

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

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Cost of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Excludes equity method investment and investment in equity security without readily determinable fair value.

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