| Pay vs Performance Disclosure - USD ($) | 12 Months Ended |
| Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 |
| Pay vs Performance Disclosure [Table] | | | |
| Pay vs Performance [Table Text Block] | Year Summary Compensation Table Total for PEO(1) Compensation Actually Paid to PEO(1)(2)(3) Average Summary Compensation Table Total for Non-PEO NEOs(1) Average Compensation Actually Paid to Non-PEO NEOs(1)(2)(3) Value of Initial Fixed $100 Investment based on:(4) Net Income(5) Net Product Sales(6) Total Shareholder Return Peer Group Total Shareholder Return (a) (b) (c) (d) (e) (f) (g) (h) (i) 2022 $ 5,753,490 $ 687,242 $ 2,238,982 $ 1,118,268 $ 148.10 $ 113.65 $ (278) $ 201 2021 $ 5,739,010 $ 6,564,795 $ 2,138,273 $ 1,957,099 $ 218.59 $ 126.45 $ (180) $ 211 2020 $ 5,447,879 $ 10,291,743 $ 1,640,653 $ 2,924,753 $ 191.94 $ 126.42 $ (169) $ 198 | | |
| Company Selected Measure Name | net product sales | | |
| Named Executive Officers, Footnote [Text Block] | Eric Dube was our PEO for each year presented. The individuals comprising the Non-PEO NEOs for each year presented are listed below. 2022: Laura Clague, Christopher Cline, Peter Heerma, Jula Inrig and William E. Rote. 2021: Laura Clague, Elizabeth Reed, Noah Rosenberg and William E. Rote. 2020: Laura Clague, Elizabeth Reed, Noah Rosenberg and William E. Rote. | | |
| Peer Group Issuers, Footnote [Text Block] | The Peer Group TSR set forth in this table utilizes the NASDAQ Biotechnology Index, which we also utilize in the stock performance graph required by Item 201(e) of Regulation S-K included in our Annual Report for the year ended December 31, 2022. The comparison assumed $100 was invested for the period starting December 31, 2019, through the end of the listed year in the Company and in the NASDAQ Biotechnology Index, respectively. Historical stock performance is not necessarily indicative of future stock performance. | | |
| PEO Total Compensation Amount | $ 5,753,490 | $ 5,739,010 | $ 5,447,879 |
| PEO Actually Paid Compensation Amount | $ 687,242 | 6,564,795 | 10,291,743 |
| Adjustment To PEO Compensation, Footnote [Text Block] | Compensation Actually Paid is computed in accordance with Item 402(v) of Regulation S-K for the PEO and the Non-PEO NEOs as set forth below. Equity values are calculated in accordance with FASB ASC Topic 718. Amounts in the Stock Awards and Options Awards column are the total from the Stock Awards and Option Awards columns set forth in the Summary Compensation Table for the applicable year. Year Summary Compensation Table Total for PEO Deduct: Stock Awards and Option Awards for PEO Add: Total Equity Adjustments for PEO Compensation Actually Paid to PEO 2022 $ 5,753,490 $ (4,403,197) $ (663,051) $ 687,242 2021 $ 5,739,010 $ (4,465,329) $ 5,291,114 $ 6,564,795 2020 $ 5,447,879 $ (4,318,090) $ 9,161,954 $ 10,291,743 Year Average Summary Compensation Table Total for Non-PEO NEOs Deduct: Average of Stock Awards and Option Awards for Non-PEO NEOs Add: Average Equity Adjustments for Non-PEO NEOs Average Compensation Actually Paid to Non-PEO NEOs 2022 $ 2,238,982 $ (1,528,507) $ 407,793 $ 1,118,268 2021 $ 2,138,273 $ (1,194,394) $ 1,013,220 $ 1,957,099 2020 $ 1,640,653 $ (941,097) $ 2,225,197 $ 2,924,753 The amounts in the Total Equity Adjustments columns in the tables above are derived from the amounts set forth in the following tables: Year Year-End Fair Value of Equity Awards Granted During Year That Remained Unvested as of Last Day of Year for PEO Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards for PEO Vesting-Date Fair Value of Equity Awards Granted During Year that Vested During Year for PEO Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year for PEO Fair Value of Last Day of Prior Year of Equity Awards Forfeited During Year for PEO Total Equity Adjustments for PEO 2022 $ 3,265,565 $ (2,562,360) $ — $ (1,366,256) $ — $ (663,051) 2021 $ 5,046,221 $ 1,091,638 $ — $ (846,745) $ — $ 5,291,114 2020 $ 7,633,746 $ 1,437,904 $ — $ 90,304 $ — $ 9,161,954 Year Average Year-End Fair Value of Equity Awards Granted During Year That Remained Unvested as of Last Day of Year for Non-PEO NEOs Average Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards for Non-PEO NEOs Average Vesting-Date Fair Value of Equity Awards Granted During Year that Vested During Year for Non-PEO NEOs Average Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year for Non-PEO NEOs Average Fair Value of Last Day of Prior Year of Equity Awards Forfeited During Year for Non-PEO NEOs Total Average Equity Adjustments for Non-PEO NEOs 2022 $ 1,094,962 $ (445,897) $ — $ (241,272) $ — $ 407,793 2021 $ 1,135,051 $ 187,774 $ — $ (215,606) $ (93,999) $ 1,013,220 2020 $ 1,662,986 $ 442,368 $ — $ 119,843 $ — $ 2,225,197 | | |
| Non-PEO NEO Average Total Compensation Amount | $ 2,238,982 | 2,138,273 | 1,640,653 |
| Non-PEO NEO Average Compensation Actually Paid Amount | $ 1,118,268 | 1,957,099 | 2,924,753 |
| Adjustment to Non-PEO NEO Compensation Footnote [Text Block] | Compensation Actually Paid is computed in accordance with Item 402(v) of Regulation S-K for the PEO and the Non-PEO NEOs as set forth below. Equity values are calculated in accordance with FASB ASC Topic 718. Amounts in the Stock Awards and Options Awards column are the total from the Stock Awards and Option Awards columns set forth in the Summary Compensation Table for the applicable year. Year Summary Compensation Table Total for PEO Deduct: Stock Awards and Option Awards for PEO Add: Total Equity Adjustments for PEO Compensation Actually Paid to PEO 2022 $ 5,753,490 $ (4,403,197) $ (663,051) $ 687,242 2021 $ 5,739,010 $ (4,465,329) $ 5,291,114 $ 6,564,795 2020 $ 5,447,879 $ (4,318,090) $ 9,161,954 $ 10,291,743 Year Average Summary Compensation Table Total for Non-PEO NEOs Deduct: Average of Stock Awards and Option Awards for Non-PEO NEOs Add: Average Equity Adjustments for Non-PEO NEOs Average Compensation Actually Paid to Non-PEO NEOs 2022 $ 2,238,982 $ (1,528,507) $ 407,793 $ 1,118,268 2021 $ 2,138,273 $ (1,194,394) $ 1,013,220 $ 1,957,099 2020 $ 1,640,653 $ (941,097) $ 2,225,197 $ 2,924,753 The amounts in the Total Equity Adjustments columns in the tables above are derived from the amounts set forth in the following tables: Year Year-End Fair Value of Equity Awards Granted During Year That Remained Unvested as of Last Day of Year for PEO Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards for PEO Vesting-Date Fair Value of Equity Awards Granted During Year that Vested During Year for PEO Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year for PEO Fair Value of Last Day of Prior Year of Equity Awards Forfeited During Year for PEO Total Equity Adjustments for PEO 2022 $ 3,265,565 $ (2,562,360) $ — $ (1,366,256) $ — $ (663,051) 2021 $ 5,046,221 $ 1,091,638 $ — $ (846,745) $ — $ 5,291,114 2020 $ 7,633,746 $ 1,437,904 $ — $ 90,304 $ — $ 9,161,954 Year Average Year-End Fair Value of Equity Awards Granted During Year That Remained Unvested as of Last Day of Year for Non-PEO NEOs Average Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards for Non-PEO NEOs Average Vesting-Date Fair Value of Equity Awards Granted During Year that Vested During Year for Non-PEO NEOs Average Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year for Non-PEO NEOs Average Fair Value of Last Day of Prior Year of Equity Awards Forfeited During Year for Non-PEO NEOs Total Average Equity Adjustments for Non-PEO NEOs 2022 $ 1,094,962 $ (445,897) $ — $ (241,272) $ — $ 407,793 2021 $ 1,135,051 $ 187,774 $ — $ (215,606) $ (93,999) $ 1,013,220 2020 $ 1,662,986 $ 442,368 $ — $ 119,843 $ — $ 2,225,197 | | |
| Compensation Actually Paid vs. Total Shareholder Return [Text Block] | Description of Relationship Between PEO and Non-PEO NEO Compensation Actually Paid and Company Total Shareholder Return ("TSR") The following chart sets forth the relationship between Compensation Actually Paid to our PEO, the average of Compensation Actually Paid to our Non-PEO NEOs, and the Company's cumulative TSR over the three most recently completed fiscal years. | | |
| Compensation Actually Paid vs. Net Income [Text Block] | Description of Relationship Between PEO and Non-PEO NEO Compensation Actually Paid and Net Income The following chart sets forth the relationship between Compensation Actually Paid to our PEO, the average of Compensation Actually Paid to our Non-PEO NEOs, and our net income during the three most recently completed fiscal years. | | |
| Compensation Actually Paid vs. Company Selected Measure [Text Block] | Description of Relationship Between PEO and Other NEO Compensation Actually Paid and Net Product Sales The following chart sets forth the relationship between Compensation Actually Paid to our PEO, the average of Compensation Actually Paid to our Non-PEO NEOs, and our net product sales during the three most recently completed fiscal years. | | |
| Total Shareholder Return Vs Peer Group [Text Block] | Description of Relationship Between Company TSR and Peer Group TSR The following chart compares our cumulative TSR over the three most recently completed fiscal years to that of the NASDAQ Biotechnology Index over the same period. | | |
| Tabular List [Table Text Block] | Net Product Sales | | |
| Total Shareholder Return Amount | $ 148.10 | 218.59 | 191.94 |
| Peer Group Total Shareholder Return Amount | 113.65 | 126.45 | 126.42 |
| Net Income (Loss) | $ (278,000,000) | $ (180,000,000) | $ (169,000,000) |
| Company Selected Measure Amount | 201,000,000 | 211,000,000 | 198,000,000 |
| PEO Name | (1)Eric Dube | | |
| Additional 402(v) Disclosure [Text Block] | Pay Versus Performance In accordance with rules adopted by the Securities and Exchange Commission pursuant to the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2020, we provide the following disclosure regarding executive compensation for our principle executive officer ("PEO") and Non-PEO NEOs and Company performance for the fiscal years listed below. The Compensation Committee did not consider the pay versus performance disclosure below in making its pay decisions for any of the years shown. Required Tabular Disclosure of Pay Versus Performance The amounts set forth below under the headings “Compensation Actually Paid to PEO” and “Average Compensation Actually Paid to non-PEO NEOs” have been calculated in a manner consistent with Item 402(v) of Regulation S-K. Use of the term “compensation actually paid” is required by the SEC’s rules and as a result of the calculation methodology required by the SEC, such amounts differ from compensation actually received by the individuals and the compensation decisions described in the “Compensation Discussion and Analysis” section above. Required Tabular List of Most Important Financial Performance Measures As is the case with many companies of a similar stage in the biotechnology industry, the Company relies less on financial performance goals as compared to non-financial strategic and operational goals with respect to setting compensation for the NEOs. For the fiscal year ended December 31, 2022, the only financial performance measure used to link Compensation Actually Paid to our NEOs to company performance was net product sales, which is the company-selected financial measure listed below. For a discussion of the non-financial strategic and operational goals the Company factors into the compensation program for the NEOs, please see the “Compensation Discussion and Analysis” section above. | | |
| Measure [Axis]: 1 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Net Product Sales | | |
| Non-GAAP Measure Description [Text Block] | We determined net product sales to be the most important financial performance measure used to link Company performance to Compensation Actually Paid to our PEO and Non-PEO NEOs in 2022. This performance measure may not have been the most important financial performance measure for years 2021 and 2020 and we may determine a different financial performance measure to be the most important financial performance measure in future years. | | |
| PEO [Member] | Equity Awards Reported Value [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | $ (4,403,197) | $ (4,465,329) | $ (4,318,090) |
| PEO [Member] | Equity Award Adjustments [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (663,051) | 5,291,114 | 9,161,954 |
| PEO [Member] | Equity Awards Granted During the Year, Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 3,265,565 | 5,046,221 | 7,633,746 |
| PEO [Member] | Equity Awards Granted in Prior Years, Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | (2,562,360) | 1,091,638 | 1,437,904 |
| PEO [Member] | Equity Awards Granted During the Year, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 0 | 0 | 0 |
| PEO [Member] | Equity Awards Granted in Prior Years, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | (1,366,256) | (846,745) | 90,304 |
| PEO [Member] | Equity Awards Granted in Prior Years, Forfeited [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 0 | 0 | 0 |
| Non-PEO NEO [Member] | Equity Awards Reported Value [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (1,528,507) | (1,194,394) | (941,097) |
| Non-PEO NEO [Member] | Equity Award Adjustments [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 407,793 | 1,013,220 | 2,225,197 |
| Non-PEO NEO [Member] | Equity Awards Granted During the Year, Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 1,094,962 | 1,135,051 | 1,662,986 |
| Non-PEO NEO [Member] | Equity Awards Granted in Prior Years, Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | (445,897) | 187,774 | 442,368 |
| Non-PEO NEO [Member] | Equity Awards Granted During the Year, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 0 | 0 | 0 |
| Non-PEO NEO [Member] | Equity Awards Granted in Prior Years, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | (241,272) | (215,606) | 119,843 |
| Non-PEO NEO [Member] | Equity Awards Granted in Prior Years, Forfeited [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | $ 0 | $ (93,999) | $ 0 |
