Organization, Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details)			1 Months Ended	3 Months Ended				4 Months Ended	9 Months Ended		12 Months Ended
	Oct. 29, 2019 USD ($) shares	Oct. 11, 2019 shares	May 31, 2019 shares	Sep. 30, 2020 USD ($) shares	Mar. 31, 2020 USD ($)	Sep. 30, 2019 shares	Jun. 30, 2019 shares	May 06, 2019 shares	Sep. 30, 2020 USD ($) Segment shares	Sep. 30, 2019 USD ($) shares	Dec. 31, 2019 USD ($) shares
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Proceeds from Initial Public Offering (IPO)										$ (1,299,000)
Description of forward stock split		2.168-for-1
Forward stock split conversion ratio		2.168
Common stock, shares authorized | shares		50,000,000		400,000,000					400,000,000		400,000,000
Fair value liabilities, level 1 to level 2 transfers, amount				$ 0					$ 0		$ 0
Fair value liabilities, level 2 to level 1 transfers, amount				$ 0					0		0
Fair value liability, transfers into level 3									0		0
Fair value liability, transfers out of level 3									0		$ 0
Conversion of Lender Warrants into equity					$ 318,000
Impairment losses									$ 0
Number of operating segment | Segment									1
Accounting Standards Update 2016-13
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Change in accounting principle, Accounting Standards Update, adopted [true false]				true					true
Change in accounting principle, Accounting Standards Update, Adoption date				Jan. 01, 2020					Jan. 01, 2020
Change in accounting principle, Accounting Standards Update, Immaterial effect [true false]				true					true
Accounting Standards Update 2018-13
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Change in accounting principle, Accounting Standards Update, adopted [true false]				true					true
Change in accounting principle, Accounting Standards Update, Adoption date				Jan. 01, 2020					Jan. 01, 2020
Change in accounting principle, Accounting Standards Update, Immaterial effect [true false]				true					true
Unvested Shares
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Weighted-average unvested shares | shares				3,186,269		4,550,428			3,606,378	3,342,544
Furniture and Fixtures
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Property and equipment, useful life									3 years
Minimum | Computer Equipment and Related Software
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Property and equipment, useful life									2 years
Maximum | Computer Equipment and Related Software
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Property and equipment, useful life									3 years
Lender Warrants
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Expected cash dividend yield									0.00%
Takeda Warrant | Takeda License | Takeda
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Shares of common stock included in calculation of basic weighted-average common shares | shares				7,588,000					7,588,000
Fair Value, Recurring
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Financial assets fair value disclosure				$ 0					$ 0
Fair Value, Nonrecurring
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Non-financial assets fair value disclosure				0					0
Non-financial liabilities fair value disclosure				$ 0					0
Common Stock
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Common stock shares issued | shares								2,524,852
Common Stock | Takeda License
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Common stock shares issued | shares			1,084,000				1,084,000
Additional Paid-in Capital
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Conversion of Lender Warrants into equity					$ 318,000
Additional Paid-in Capital | Lender Warrants
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Conversion of Lender Warrants into equity									$ 300,000
IPO | Common Stock
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Common stock shares issued | shares	10,997,630
Proceeds from Initial Public Offering (IPO)	$ 191,500,000