Closing price of common stock.

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Share based compensation arrangement by share based payment average market capitalization threshold satisfaction period.

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- Definition

Share based compensation arrangement by share based payment equal to or greater than average market capital.

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- Definition

Share based compensation by share based payment award percentage of exercise price of options granted.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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- Definition

Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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- Definition

Amount of cost to be recognized for option under share-based payment arrangement.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Description of service or performance condition required to be met for earning right to award under share-based payment arrangement. Includes, but is not limited to, combination of market, performance or service condition.

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Description of terms of share-based payment arrangement. Includes, but is not limited to, type of award or grantee and reason for issuance.

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- Definition

Discount rate from fair value on purchase date that participants pay for shares.

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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

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

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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 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

Number of options outstanding, including both vested and non-vested options.

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- Definition

Number of shares purchased for issuance under share-based payment arrangement.

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- Definition

Percentage of vesting of award under share-based payment arrangement.

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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

Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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- Definition

Number of non-vested options outstanding.

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- Definition

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

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Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested shares subject to repurchase rights	0		0		0
Vesting period			4 years
Vesting rate at the end of one year			25.00%
vesting rights description			Options granted to new hires generally vest over a four-year period, with 25% vesting at the end of one year and the remaining vesting monthly thereafter. Options granted as merit awards generally vest monthly over a three- or four-year period.
Closing price of common stock	$ 12.97		$ 12.97
Weighted-average grant date fair value of options granted	$ 6.70	$ 8.40	$ 4.81	$ 8.07
Unrecognized stock-based compensation cost of unvested options	$ 12.0		$ 12.0
Unrecognized stock-based compensation of unvested options, recognized over weighted-average period			2 years 7 months 6 days
Dividend yield	0.00%	0.00%	0.00%	0.00%
Options Granted as Merit Awards \| Tranche One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period			3 years
Options Granted as Merit Awards \| Tranche Two
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period			4 years
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period			4 years
Closing price of common stock	$ 12.97		$ 12.97
Unrecognized stock-based compensation of unvested options, recognized over weighted-average period			3 years 1 month 6 days
Unrecognized stock-based compensation cost of unvested RSUs	$ 5.0		$ 5.0
Restricted Stock Units \| Tranche One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period			3 years
Restricted Stock Units \| Tranche Two
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period			3 years
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average expected life	6 years 29 days	6 years 29 days	6 years 29 days	6 years 10 months 13 days
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average expected life	5 years 6 months	5 years	5 years 6 months	5 years
2011 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Performance-based Options granted	3,902,797		3,902,797		4,474,057
2011 Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted in years			10 years
2019 Plan \| Performance-Based Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted in years			10 years
Closing price of common stock	$ 12.97		$ 12.97
Unrecognized stock-based compensation cost of unvested options	$ 1.3		$ 1.3
Unrecognized stock-based compensation of unvested options, recognized over weighted-average period			4 years 3 months 18 days
Performance-based Options granted	421,000		421,000
Share based compensation arrangement by share based payment equal to or greater than average market capital			$ 1,000.0
Average market capitalization threshold satisfaction period			30 days
Share based compensation arrangement by share based payment award description			The shares subject to the PSO will vest in full if the Company’s average market capitalization is equal to or greater than $1 billion over a 30 calendar day period. Upon a change in control, the vesting of the shares subject to the PSO will accelerate on a pro rata basis based on the price per share in such change in control transaction multiplied by the price per share at such time divided by $1 billion, with up to 100% of the shares eligible for such accelerated vesting.
Weighted-average expected life			10 years
Expected volatility			63.60%
Risk-free interest rate			1.02%
2019 Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted in years			10 years
2019 Plan \| Maximum \| Performance-Based Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting rate at the end of one year			100.00%
2019 Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of exercise price options granted			100.00%
2019 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of purchase price of common stock			85.00%
Common stock shares purchased			71,480
Weighted-average expected life			6 months
Expected volatility			102.10%
Risk-free interest rate			0.10%
Dividend yield			0.00%
2019 Employee Stock Purchase Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of earnings for purchase of common stock at discounted price			15.00%