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Share based compensation arrangement by share based payment award number of shares available for grant annual increase.

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Shares aggregate repurchase price.

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

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

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

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

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Number of new stock issued during the period.

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Expiration date for the purchase of an entity's own shares under a stock repurchase plan, in the CCYY-MM-DD format.

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The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

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Period which shares may be purchased under a stock repurchase plan authorized by an entity's Board of Directors, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The remaining number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

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Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended				3 Months Ended	4 Months Ended	12 Months Ended
	Oct. 29, 2019	Nov. 30, 2019	Oct. 31, 2019	May 31, 2019	Mar. 31, 2019	Mar. 31, 2020	May 06, 2019	Dec. 31, 2019	Jan. 01, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options, granted						134,227
Common stock initially reserved for issuance						13,423,199
Expected dividend yield						0.00%
Unrecognized stock-based compensation expense						$ 9,000
Unrecognized stock-based compensation expense, weighted-average period for recognition						3 years 6 months 21 days
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock initially reserved for issuance						1,534,755
Expected dividend yield						0.00%
2019 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares authorized for issuance								2,231,739
Stock options, granted								1,400,528
Number of shares available for issuance						0
2019 Equity Incentive Plan \| Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock awards, granted								16,260
2019 Incentive Award Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options, granted						134,227
Annual increase to shares available for issuance percentage of outstanding common stock			5.00%
Equity plan, description			The number of shares initially available for issuance will be increased by (i) the number of shares subject to stock options or similar awards granted under the Existing Incentive Plan that expire or otherwise terminate without having been exercised in full after the effective date of the 2019 Plan and unvested shares issued pursuant to awards granted under the Existing Incentive Plan that are forfeited to or repurchased by the Company after the effective date of the 2019 Plan, with the maximum number of shares to be added to the 2019 Plan pursuant to clause (i) above equal to 1,416,788 shares, and (ii) an annual increase on January 1 of each calendar year beginning in 2020 and ending in 2029, equal to the lesser of (a) 5% of the shares of common stock outstanding on the final day of the immediately preceding calendar year and (b) such smaller number of shares as determined by the board of directors. The Company initially had 2,700,000 shares of common stock available for issuance under the 2019 Plan, of which, 134,227 stock options were granted. As of March 31, 2020, 3,724,353 shares remain available for issuance, which includes the annual increase of 1,158,580 shares that were authorized on January 1, 2020.
Number of shares remain available for issuance, annual increase									1,158,580
Common stock initially reserved for issuance						3,724,353
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for issuance						559,645
Annual increase to shares available for issuance percentage of outstanding common stock			1.00%
Equity plan, description			In addition, the number of shares available for issuance under the ESPP will be annually increased on January 1 of each calendar year beginning in 2020 and ending in 2029, by an amount equal to the lesser of: (i) 1% of the shares outstanding on the final day of the immediately preceding calendar year and (ii) such smaller number of shares as is determined by the board of directors. As of March 31, 2020, 559,645 shares of common stock remain available for issuance, which includes the annual increase of 289,645 shares that were authorized on January 1, 2020.
Number of shares remain available for issuance, annual increase									289,645
Common stock initially reserved for issuance			270,000			559,645
Employee and Nonemployee Director
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Estimated weighted-average fair value						$ 19.92
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued							2,524,852
Number of shares authorized to repurchase					3,373,408
Stock repurchase program, number of shares right lapse					843,352
Remaining number of shares to be repurchased					2,530,056
Stock repurchase program, period in force					48 months
Stock repurchase program expiration date					Mar. 31, 2023
Proceeds from issuance of common stock							$ 1,000
Repurchase right lapse each month after first anniversary, shares							0.000208
Repurchases of shares		17,560
Shares aggregate repurchase price		$ 5.20
Common Stock \| 2019 Incentive Award Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares authorized for issuance			2,700,000
Number of shares available for issuance						3,724,353
Additional number of shares available for issuance			1,416,788
Common Stock \| Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum percentage of eligible compensation contributed by participants			20.00%
Common Stock \| IPO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued	10,997,630
Common stock, price per share	$ 19.00
Proceeds from Initial Public Offering (IPO)	$ 191,500
Common Stock \| Underwriters
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued	1,434,473
Common Stock \| Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Remaining number of shares to be repurchased						1,913,393
Common Stock \| First Anniversary
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Repurchase right lapse rate							25.00%
Common Stock \| Takeda License
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued				1,084,000
Common Stock \| Founders
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Remaining number of shares to be repurchased						1,897,560
Common Stock \| Frazier
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued					1,491,072