Debt - Convertible Note Hedge and Warrant Transactions (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	Apr. 27, 2019	Sep. 15, 2015
Convertible Note Hedge
Debt Instrument [Line Items]
Derivative, Number of Instruments Held		5,006
Debt instrument, convertible, conversion price (per share)	$ 96.89	$ 96.89
Deferred tax liability		$ 43.4
Deferred tax asset, derivative instrument		$ 43.2
0.75% Convertible Senior Notes Due 2021
Debt Instrument [Line Items]
Debt instrument, convertible, conversion price (per share)		$ 96.89
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (shares)		5,006
Class of warrant or right, exercise price of warrants or rights (per warrant)	$ 130.43	$ 130.43

Exercise price per share or per unit of warrants or rights outstanding.

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Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

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The price per share of the conversion feature embedded in the debt instrument.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from derivative instruments.

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Amount of deferred tax liability attributable to taxable temporary differences from derivatives.

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The number of derivative instruments of a particular group held by the entity.

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