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Increase (decrease) in stock-based compensation expense.

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Initial offering period end date.

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Initial offering period start date.

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award, Number Of Offering Periods

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award, Offering Period

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award, Purchase Period

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- Definition

Stock modified during period shares restricted stock units.

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- Definition

Stock options modified in exchanged.

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- Definition

Aggregate number of common shares reserved for future issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29)
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- Definition

Unrecognized cost of unvested share-based compensation awards.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
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- Definition

Unrecognized cost of unvested options awarded to employees as compensation.

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- Definition

Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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-Paragraph 2
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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

For each plan, identification of the award pricing model or other valuation method used in calculating the weighted average fair values disclosed. The model is also used to calculate the compensation expense that is shown within the balance sheet, income statement, and cash flow. Examples of valuation techniques are lattice models (binomial model), closed-form models (Black-Scholes-Merton formula), and a Monte Carlo simulation technique. Fair value is the amount at which an asset or liability could be bought or incurred or sold or settled in a current transaction between willing parties, that is, other than in a forced or liquidation sale. May include disclosures about the assumptions underlying application of the method selected.

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-Paragraph 2
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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.

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No definition available.

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- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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- Definition

Gross number of share options (or share units) granted during the period.

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No definition available.

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- Definition

Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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No definition available.

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- Definition

Price of a single share of a number of saleable stocks of a company.

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- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Purchase price of common stock expressed as a percentage of its fair value.

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Stockholders' Equity and Employee Benefit Plans - Additional Information (Details) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended		19 Months Ended
	Aug. 21, 2015 USD ($) $ / shares shares	Mar. 31, 2018 shares	Jun. 30, 2017 shares	Sep. 30, 2018 USD ($) offering_period $ / shares shares	Sep. 30, 2017 USD ($) $ / shares	May 31, 2015 $ / shares shares	Sep. 05, 2018 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				4 years
Stock options granted				5,455,835		16,700,000
Stock options granted, price per share \| $ / shares				$ 13.32		$ 42.33
Stock-based compensation expense \| $	$ 19,800			$ 93,685
Recognized service period of new award	4 years
Unrecognized compensation expense relating to repriced and exchanged awards \| $				$ 2,000
August 2015 Modification
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted	6,000,000
Stock options granted, price per share \| $ / shares	$ 16.03
Stock options exchanged	11,900,000
Unrecognized share-based compensation expense, recognition end year				2019
Second Quarter 2017 Modification \| Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awards			500,000
Stock-based compensation expense \| $					$ (1,100)
Second Quarter 2018 Modification \| Research and Development and Sales and Marketing Costs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awards		500,000
Stock-based compensation expense \| $				$ (500)
Out-of-the-Money Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value assumptions, method used				Lattice-Binomial Option Valuation Model
Fair value of common stock \| $ / shares					$ 11.84
At-the-Money Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value assumptions, method used				Black-Scholes Valuation Model
Maximum \| At-the-Money Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of common stock \| $ / shares				$ 13.65
Minimum \| At-the-Money Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of common stock \| $ / shares				$ 12.00
Common Stock \| Accounting Standards Update 2016-09
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of common stock \| $ / shares	$ 14.38
2018 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares reserved							9,394,744
2018 Equity Incentive Plan \| Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant				13,906,190
Equity Incentive Plans \| Time-Based Awards \| New Hires
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				4 years
Equity Incentive Plans \| Time-Based Awards \| Existing Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				3 years
Equity Incentive Plans \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period				10 years
2018 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares reserved							2,673,444
Offering period				24 months
Number of offering periods \| offering_period				4
Length of purchase period				6 months
Employee share purchase price percentage				85.00%
Initial offering period start date				Sep. 25, 2018
Initial offering period end date				Nov. 22, 2020
2018 Employee Stock Purchase Plan \| Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant				2,673,444