Revenue - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended		12 Months Ended
	Jan. 31, 2022	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2019	Dec. 31, 2021
Disaggregation Of Revenue [Line Items]
Accounts receivable		$ 2,923,000			$ 2,765,000
Neurocrine Biosciences [Member]
Disaggregation Of Revenue [Line Items]
Accounts receivable		1,418,000
Neurocrine Biosciences [Member] | Collaboration Revenue [Member]
Disaggregation Of Revenue [Line Items]
Research and development services		1,270,000	$ 1,358,000
Milestone payments		7,124,000	0
Pacira BioSciences [Member] | Collaboration Revenue [Member]
Disaggregation Of Revenue [Line Items]
Milestone payments		0	3,000,000
License and Collaboration Agreement [Member] | Neurocrine Biosciences [Member]
Disaggregation Of Revenue [Line Items]
Upfront payment received in cash				$ 30,000,000
Upfront payment received in equity investment				20,000,000
Equity investment measured at fair value				16,667,000
Collaborate agreement premium related to equity investment				3,333,000
Transaction price allocated to performance obligations				33,333,000
Milestone Payment Received	$ 15,000,000
Milestone Payment Received in Cash	6,750,000
Milestone Payment Received in Equity Investment	8,250,000
Equity investment measure at fair value	7,876,000
Premium	374,000
Revenue	6,750,000
Performance obligation related to milestone	$ 0
Potential milestone payments receivable		$ 1,667,500,000
Percentage of option to co-fund development costs upon achievement of certain milestones		50.00%
License and Collaboration Agreement [Member] | Neurocrine Biosciences [Member] | Regulatory Milestone [Member]
Disaggregation Of Revenue [Line Items]
Potential milestone payments receivable		$ 1,067,500,000
License and Collaboration Agreement [Member] | Neurocrine Biosciences [Member] | Sales Based Milestone [Member]
Disaggregation Of Revenue [Line Items]
Potential milestone payments receivable		600,000,000
License and Collaboration Agreement [Member] | Exclusive License to XEN901 and Exclusive License to DTCs [Member] | Neurocrine Biosciences [Member]
Disaggregation Of Revenue [Line Items]
Transaction price allocated to performance obligations				$ 28,807,000
License and Collaboration Agreement [Member] | Development Services Under the Initial Development Program For DTCs [Member] | Neurocrine Biosciences [Member]
Disaggregation Of Revenue [Line Items]
Transaction price allocated to performance obligations		5,025,000
Variable consideration allocated to performance obligation		499,000
Asset Purchase Agreement [Member] | Pacira BioSciences [Member] | XEN402 [Member]
Disaggregation Of Revenue [Line Items]
Milestone payments			1,000,000
Milestone payment due on initiation of Phase 1b clinical trial			$ 2,000,000
Asset Purchase Agreement [Member] | Eligible to Receive Development Milestone Payment [Member] | Pacira BioSciences [Member] | XEN402 [Member] | Maximum [Member]
Disaggregation Of Revenue [Line Items]
Potential milestone payments receivable		5,000,000
Asset Purchase Agreement [Member] | Future Clinical Development And Global Regulatory Approval Milestone Payments [Member] | Pacira BioSciences [Member] | XEN402 [Member] | Maximum [Member]
Disaggregation Of Revenue [Line Items]
Potential milestone payments receivable		40,750,000
Asset Purchase Agreement [Member] | Commercial Milestone Payments [Member] | Pacira BioSciences [Member] | XEN402 [Member] | Maximum [Member]
Disaggregation Of Revenue [Line Items]
Potential milestone payments receivable		$ 75,000,000