Share-Based Payments - Summary of Stock Option Activity (Details) - $ / shares	9 Months Ended
Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of Stock Options, Outstanding, Beginning balance (in shares)	5,416,069
Number of Stock Options, Granted (in shares)	1,577,686
Number of Stock Options, Exercised (in shares)	(253,323)
Number of Stock Options, Forfeited/Expired (in shares)	(554,497)
Number of Stock Options, Outstanding, Ending balance (in shares)	6,185,935
Number of Stock Options, Exercisable (in shares)	3,441,309
Number of Stock Options, Vested and expected to vest (in shares)	6,185,935
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted-Average Exercise Price, Outstanding, Beginning balance (in usd per share)	$ 60.10
Weighted-Average Exercise Price, Granted (in usd per share)	55.85
Weighted-Average Exercise Price, Exercised (in usd per share)	34.51
Weighted-Average Exercise Price, Forfeited/Expired (in usd per share)	67.59
Weighted-Average Exercise Price, Outstanding, Ending balance (in usd per share)	59.39
Weighted-Average Exercise Price, Exercisable (in usd per share)	58.90
Weighted-Average Exercise Price, Vested and expected to vest (in usd per share)	$ 59.39

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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-Publisher FASB
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-Topic 718
-SubTopic 10
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Number of share options (or share units) exercised during the current period.

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