v3.8.0.1

Stock Incentive Plans - Summary Of Stock Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Shares
Beginning balance, Outstanding (in shares) | shares	320
Options awarded (in shares) | shares	1
Exercised (in shares) | shares	(178)
Forfeited (in shares) | shares	(13)
Ending balance, Outstanding (in shares) | shares	130
Exercisable (in shares) | shares	115
Weighted Average Exercise Price
Beginning Balance, Outstanding, Weighted Average Exercise Price (usd per share) | $ / shares	$ 17.44
Granted (usd per share) | $ / shares	68.60
Exercised (usd per share) | $ / shares	13.47
Forfeited (usd per share) | $ / shares	62.86
Ending Balance, Outstanding, Weighted Average Exercise Price (usd per share) | $ / shares	18.82
Exercisable, Weighted Average Exercise Price (usd per share) | $ / shares	$ 13.75
Aggregate Intrinsic Value Outstanding at end of period | $	$ 11
Aggregate Intrinsic Value Exercisable at end of Period | $	$ 10
Weighted Average Remaining Contractual Term at end of period	2 years 8 months
Weighted Average Remaining Contractual Term Exercisable at end of period	1 year 11 months

X

- Definition

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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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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.

+ References

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

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Amount by which current fair value of underlying stock exceeds exercise price of 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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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 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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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

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