Summary of UT Revenue (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenue from UT		$ 32,825	$ 22,211	$ 63,711	$ 62,927
United Therapeutics Corporation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenue from UT		16,529	12,313	24,268	33,475
Commercial Supply Agreement | United Therapeutics Corporation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenue from UT		9,916		15,795
License Agreement | United Therapeutics Corporation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenue from UT		393	$ 12,313	1,949	$ 33,475
Royalties Collaborations | United Therapeutics Corporation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenue from UT	[1]	$ 6,220		$ 6,524

[1] Amount consists of royalties associated with the UT license Agreement. The current portion of contract assets related to the royalties is included in prepaid expense and other current assets in the condensed consolidated balance sheets