Initial offering period end date.

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Initial offering period start date.

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

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

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

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- Definition

Amount of cash inflow from issuance of shares under share-based compensation arrangement, excluding stock option exercises.

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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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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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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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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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The weighted average of per share prices paid for shares purchased on the open market for issuance to employees under the plan.

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

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Number of shares issued during the period as a result of an employee stock purchase plan.

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Employee Benefit Plans - Additional Information (Details) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($) $ / shares shares	Jun. 30, 2019 USD ($) offering_period $ / shares shares	Jun. 30, 2018 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value assumptions, method used		Black-Scholes-Merton option pricing model
Proceeds under the plan \| $		$ 2,662	$ 0
2018 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
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
Time-Based Awards \| Equity Incentive Plans \| New Hires
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		4 years
Time-Based Awards \| Equity Incentive Plans \| Existing Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		3 years
Maximum \| Equity Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period		10 years
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares purchased by employees	261,000	261,000
Common Stock \| 2018 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant	9,022,261	9,022,261
Common Stock \| 2018 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant	2,412,453	2,412,453
Number of shares purchased by employees	260,991	260,991
Weighted average purchase price \| $ / shares	$ 10.20	$ 10.20
Proceeds under the plan \| $	$ 2,700	$ 2,700