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Net Income (Loss) Per Share - Additional Information (Detail) shares in Millions	9 Months Ended
	Sep. 30, 2018 shares
2.25% Convertible Senior Notes due 2024
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Share equivalents excluded from computation of earnings per share	6.8
Performance-based RSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Share equivalents excluded from computation of earnings per share	0.3

X

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

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- Definition

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.

+ References

No definition available.

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