Debt - Additional Information (Details) - USD ($)			3 Months Ended		9 Months Ended		10 Months Ended
	Sep. 17, 2021	May 14, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Mar. 16, 2020	Mar. 11, 2020
Debt Instrument [Line Items]
Term loans aggregate principal amount			$ 100,000,000		$ 100,000,000
Adjustments to additional paid-in-capital, warrants issued			1,290,000
Term Loan
Debt Instrument [Line Items]
Debt instrument borrowed amount								$ 25,000,000.0
Debt instrument, additional borrowing capacity amount							$ 25,000,000.0
Term Loan First Advance
Debt Instrument [Line Items]
Final payment of debt					54,300,000
SVB Term Loan
Debt Instrument [Line Items]
Debt instrument, maturity date		May 01, 2024
Debt instrument, final payment fee percentage		8.25%
Debt instrument, final payment fee or end of term charge			$ 4,100,000		$ 4,100,000
Fair value of warrant liabilities		$ 400,000
Debt issuance costs		$ 200,000
Debt instrument, interest rate percentage			7.25%		7.25%
Debt instrument, description					Under the original SVB Term Loan, the monthly payments consisted of interest-only through May 31, 2021. On March 11, 2020, the Company entered into the first amendment and on March 11, 2021, the Company entered into the second amendment (together the “Amendments”) to the SVB Term Loan. Pursuant to the Amendments, the interest-only payment period was initially extended through July 31, 2021, and was further extended until December 31, 2021, after the Company received positive data from its Phase 3 clinical trial in H. pylori infection sufficient to file an NDA with the FDA. The interest-only payment period could have been further extended until November 30, 2022, if the Company would receive positive data from its Phase 3 clinical trial in erosive esophagitis for vonoprazan sufficient to file an NDA with the FDA.
Debt instrument penalty fee percentage		4.00%
Warrants expire term		10 years
Warrants exercisable shares of common stock		16,446
Aggregate repurchase price of warrants		$ 500,000
Adjustments to additional paid-in-capital, warrants issued					$ 300,000
SVB Term Loan | Maximum
Debt Instrument [Line Items]
Debt instrument, prepayment fee percentage of outstanding principal amount		2.00%
SVB Term Loan | Prime Rate
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		1.75%
Loan Agreement
Debt Instrument [Line Items]
Debt instrument, final payment fee or end of term charge	$ 7,500,000
Percentage of qualified cash prior to Third performance milestone	60.00%
Minimum percentage of qualified cash following third performance milestone	35.00%
Minimum market capitalization amount	$ 900,000,000.0
Percentage of debt funded to be issued as warrants to purchase common stock	2.50%
Warrants exercise price	$ 33.43
Warrants expire term	7 years
Warrants expiration date	Sep. 17, 2028
Fair value of warrant liabilities	$ 1,300,000
Debt issuance costs	$ 3,100,000
Loan Agreement | Common Stock
Debt Instrument [Line Items]
Warrants issued to purchase shares	74,782
Loan Agreement | Term Loan
Debt Instrument [Line Items]
Term loans aggregate principal amount	$ 200,000,000.0
Payment for facility charge	$ 1,250,000
Debt instrument, facility charge percentage	0.50%
Debt instrument, maturity date	Oct. 01, 2026
Loan Agreement | Term Loan | Floor Rate
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	5.50%
Loan Agreement | Term Loan | Prime Rate
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	2.25%
Loan Agreement | Term Loan | Payment In Kind PIK Interest Rate
Debt Instrument [Line Items]
Debt instrument, interest rate	3.35%
Loan Agreement | Term Loans, Aggregate Principal Amount Tranches One
Debt Instrument [Line Items]
Term loans aggregate principal amount	$ 100,000,000.0
Loan Agreement | Term Loans, Aggregate Principal Amount Tranches Two
Debt Instrument [Line Items]
Term loans aggregate principal amount	50,000,000.0
Loan Agreement | Term Loans, Aggregate Principal Amount Tranches Three
Debt Instrument [Line Items]
Term loans aggregate principal amount	25,000,000.0
Loan Agreement | Term Loans, Aggregate Principal Amount Tranches Four
Debt Instrument [Line Items]
Term loans aggregate principal amount	$ 25,000,000.0
Loan Agreement | Term Loan Advance
Debt Instrument [Line Items]
Debt instrument, final payment fee percentage	7.50%
Debt instrument, final payment fee or end of term charge			$ 7,500,000		7,500,000
Loan Agreement | Term Loan Advance | Maximum
Debt Instrument [Line Items]
Debt instrument, prepayment fee percentage of outstanding principal amount	1.25%
Hercules and SVB Term Loan
Debt Instrument [Line Items]
Term loans aggregate principal amount			100,100,000		100,100,000
Accrued interest			200,000		200,000
Interest expense			$ 1,500,000	$ 1,300,000	$ 4,000,000.0	$ 3,300,000