Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended			9 Months Ended
	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments | segment				1
Depreciation expense	$ 500,000		$ 600,000	$ 1,600,000	$ 1,700,000
Impairment of intangible asset	0	$ 115,500,000	0	115,527,000	0
Remeasurements to property and equipment	0		0	0	0
Other asset impairments	0			$ 0
Asset impairments			0		$ 0
Otsuka U.S. Agreement
Summary Of Significant Accounting Policies [Line Items]
Cost share costs for license agreement	1,200,000		500,000
Reimbursable by Otsuka	500,000		200,000
Cost share costs by partner for license agreement	500,000		300,000
Reimbursable to Otsuka	$ 300,000		$ 200,000
Minimum
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life				3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life				7 years