Share based compensation arrangement by share based payment award award vesting period interval.

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Share based compensation arrangement by share based payment award fair market value trading days.

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- Definition

Share based compensation arrangement by share based payment award increased number of shares authorized as percentage of outstanding common stock.

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- Definition

StockBasedCompensationExpense.

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Aggregate number of common shares reserved for future issuance.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Aggregate carrying value as of the balance sheet date of the liabilities for stock option plans and other equity-based compensation arrangements.

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Unrecognized cost of unvested options awarded to employees as compensation.

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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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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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- Definition

Discloses use of the simplified method to calculate the expected term that stock option awards under the specified plan will exist before being exercised or terminated, the reason and justification for its use, and the periods for which the method was used if it was not used in all periods presented.

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-Topic 718
-SubTopic 10
-Section S99
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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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- Definition

Number of additional shares authorized for issuance under an established share-based compensation plan.

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No definition available.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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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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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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- Definition

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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- Definition

Maximum number of shares that may be issued in accordance with the plan as a proportion of outstanding capital stock.

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No definition available.

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Number of share instruments newly issued under a share-based compensation plan.

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Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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

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Number of shares of capital stock issued (purchased by employees) in connection with an employee stock ownership plan.

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Aggregate value of stock issued during the period as a result of employee stock ownership plan (ESOP).

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Stock-Based Compensation - Additional Information (Details) - USD ($)		3 Months Ended	12 Months Ended
	Jan. 01, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for issuance			3,801,191	1,855,240	1,283,375	871,226
Total shares of authorized common stock reserved for future issuance			5,259,271	32,858,930
Common stock, shares outstanding			44,537,946	4,090,898
Description of expected term simplified method			The Company has opted to use the “simplified method” for estimating the expected term of options, whereby the expected term equals the arithmetic average of the vesting term and the original contractual term of the option (generally 10 years).
Expected term			10 years
Expected dividend yield			0.00%
Unrecognized employee compensation costs			$ 11,000,000	$ 1,900,000	$ 400,000
Intrinsic value of shares exercised			600,000	2,500,000	1,200,000
Fair value of shares vested			$ 3,000,000	$ 500,000	$ 100,000
Share-based compensation, vested stock options			14,918	63,878	37,311
Non-Employee Stock-Based Compensation
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares not vested and subject to repurchase			31,388	77,466	47,971
Stock based compensation expense			$ 300,000
Restricted Stock Agreements
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period						4 years
Estimated fair value, price per share						$ 0.0004
Vesting interval period						monthly
Restricted Stock Agreements \| Chief Executive Officer and President
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued						2,777,776
Price per share						$ 0.0004
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares issued or transferred		3,570,000
Number of shares of common stock reserved for issuance			3,801,191
2018 Equity Incentive Plan \| Maximum \| Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional number of shares reserved for issuance each year	3,570,000
Percentage of common stock outstanding	4.00%
2015 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for issuance		709,558
Shares not vested and subject to repurchase			927,123	812,769
Cash received from early exercise of unvested options			$ 2,800,000	$ 900,000
Award vesting period			48 months
2018 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase date of fair market value trading days		24 months
Total shares of authorized common stock reserved for future issuance		714,000
2018 Employee Stock Purchase Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase price of common stock as percentage of market value		85.00%
Number of shares of common stock that may be purchased by an employee on any purchase date		3,000
Number of shares that may be purchased in any calendar year		$ 25,000
2018 Employee Stock Purchase Plan \| Maximum \| Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of common stock shares outstanding	1.00%
Common stock, shares outstanding	1,071,000