Stock-Based Compensation - Options Activity (Details) shares in Thousands	3 Months Ended
Mar. 31, 2018 $ / shares shares
Shares (in thousands)
December 31, 2017 (in shares) \| shares	3,392
Granted (in shares) \| shares	490
Exercised (in shares) \| shares	(102)
Canceled (in shares) \| shares	(7)
March 31, 2018 (in shares) \| shares	3,773
Weighted- Average Exercise Price per Share
Outstanding weighted average exercise price, beginning balance (in usd per share) \| $ / shares	$ 14.41
Granted weighted average exercise price (in usd per share \| $ / shares	42.37
Exercised weighted average exercise price (in usd per share \| $ / shares	19.09
Canceled weighted average exercise price (in usd per share \| $ / shares	19.00
Outstanding weighted average exercise price, ending balance (in usd per share \| $ / shares	$ 17.90

Weighted average price of options that were either forfeited or expired.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)-(4)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
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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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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

+ References

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-Publisher FASB
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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 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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