Accounts Receivable - Additional Information (Detail)	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2022 USD ($)	Sep. 30, 2022 USD ($) Distributor	Dec. 31, 2021 Distributor
Accounts Receivable [Line Items]
Number of wholesale distributors | Distributor		3	3
Percentage of gross sales from major wholesale distributors	75.00%	73.00%	80.00%
Allowance for credit losses for accounts receivable | $	$ 0	$ 0
Percentage of revenue from major customers collaborations and services	100.00%	96.00%
United Therapeutics Corporation
Accounts Receivable [Line Items]
Percentage of collaborations and services net accounts receivables		100.00%
Commercial product sales
Accounts Receivable [Line Items]
Percentage of accounts receivable from major wholesale distributors	78.00%	78.00%	79.00%