Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

+ References

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- Definition

The cash inflow associated with the amount received from entity's raising of capital via private rather than public placement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3255-108585

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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.

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Amount of selling, general and administrative expenses resulting from transactions, excluding transactions that are eliminated in consolidated or combined financial statements, with related party.

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- Definition

Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction.

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Related Party Transactions - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended	12 Months Ended
	Jul. 22, 2015	Jul. 31, 2015	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Common stock, shares issued			44,540,544	43,018,737
Intel Security [Member]
Related Party Transaction [Line Items]
Sales and marketing expense related to partner referral fees			$ 2.7
Technology Crossover Ventures [Member]
Related Party Transaction [Line Items]
Net proceeds from offerings	$ 5.0	$ 5.0
Common stock, shares issued	312,500	312,500
Price per share equal to IPO price (in dollars per share)	$ 16.00	$ 16.00
Minimum [Member] \| Technology Crossover Ventures [Member] \| Private Placement [Member]
Related Party Transaction [Line Items]
Percentage of ownership held by stockholders		5.00%