Convertible Senior Notes - Schedule of Net Carrying Amount of the Equity Component of the Notes (Details) $ in Thousands	Jul. 31, 2018 USD ($)
Debt Instrument [Line Items]
Debt discount for conversion option	$ 84,200
Convertible Debt
Debt Instrument [Line Items]
Unamortized debt issuance costs	(8,800)
Convertible Senior Notes, Equity Component \| Convertible Debt
Debt Instrument [Line Items]
Debt discount for conversion option	84,168
Unamortized debt issuance costs	(2,485)
Net carrying amount	$ 81,683

Debt Instrument, Convertible, Gross Amount of Equity Component

No definition available.

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- Definition

The carrying amount of the equity component of convertible debt which may be settled in cash upon conversion.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6928298&loc=SL6031897-161870

+ Details

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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.

+ Details

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- Definition

Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

+ Details

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- Details

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- Details

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