Commitments and Contingencies - (CFTR Activators and Inhibitors) - Additional Information (Detail) - CFTR Activators and Inhibitors - USD ($) $ in Thousands	1 Months Ended	9 Months Ended	12 Months Ended	43 Months Ended
	Mar. 31, 2019	Sep. 30, 2020	Dec. 31, 2017	Sep. 30, 2020
Commitments and Contingencies [Line Items]
Future percentage of royalty payments based net sales		single-digit
Development and milestone obligations paid to third party				$ 1,200
Regulatory Approval Milestone
CFTR activators and inhibitors
Possible future milestone payments		$ 12,200
Future Regulatory Approval And Sales Milestones
CFTR activators and inhibitors
Possible future milestone payments		33,000
Development and Milestone Payment, Conclusion Of Phase I Study
Commitments and Contingencies [Line Items]
Development and milestone obligations paid to third party	$ 200		$ 1,000
CFTR activators and inhibitors
Possible future milestone payments		350
Maximum | Development and Milestone Payment, Conclusion Of Phase I Study
CFTR activators and inhibitors
Possible future milestone payments		$ 1,100