| Pay vs Performance Disclosure - USD ($) | 2 Months Ended | 10 Months Ended | 12 Months Ended |
| Dec. 31, 2021 | Nov. 04, 2021 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 |
| Pay vs Performance Disclosure | | | | | |
| Pay vs Performance Disclosure, Table | | | Year Summary Compensation Table Total for PEO 1¹ ($) Summary Compensation Table Total for PEO 2 1 ($) Compensation Actually Paid to PEO 1¹˒²˒³ Compensation Actually Paid to PEO 2 1,2,3 ($) 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 $100 Investment based on 4 Net Income ($ Thousands) TSR ($) 2023 3,049,181 - (608,619) - 1,336,894 179,961 5.35 (205,904) 2022 1,814,700 - (136,947) - 1,353,832 850,656 26.80 (266,578) 2021 9,258,001 7,332,683 5,104,693 1,650,578 3,075,681 1,462,375 38.70 (819,378) | | |
| Named Executive Officers, Footnote | | | Nick Leschly was our PEO until his resignation on November 4, 2021 (PEO 2). Andrew Obenshain has been our PEO since November 4, 2021 (PEO 1). The individuals comprising the Non-PEO NEOs for each year presented are listed below. 2021 2022 2023 Gina Consylman Thomas J. Klima Thomas J. Klima Jason Cole Richard A. Colvin Richard A. Colvin Thomas J. Klima Jason Cole William D. Baird, III Philip Gregory | | |
| PEO Total Compensation Amount | | | $ 3,049,181 | | |
| PEO Actually Paid Compensation Amount | | | $ (608,619) | | |
| Adjustment To PEO Compensation, Footnote | | | The "Compensation Actually Paid" columns reflect the exclusions and inclusions of certain amounts for the PEOs and the Non-PEO NEOs as set forth below for the most recent fiscal year. Equity values are calculated in accordance with FASB ASC Topic 718. Amounts in the Exclusion of Stock Awards and Option Awards column are the totals from the Stock Awards and Option Awards columns set forth in the Summary Compensation Table. The fair values of RSUs, PSUs, and stock options included in the "Compensation Actually Paid" to our PEOs and the "Average Compensation Actually Paid" to our Non-PEO NEOs columns are calculated at the required measurement dates, consistent with the approach used to value the awards at the grant date as described in our Annual Report on Form 10-K for the year ended December 31, 2023. Any changes to the RSU and PSU fair values are based on our updated stock price at the respective measurement dates and updated performance metric projections (for PSUs). Changes to the stock option fair values are based on the updated stock price at the respective measurement dates, in addition to updated expected option life, volatility, dividend yield and risk-free rate assumptions. For all years presented, the meaningful increases or decreases in the year-end stock option fair value from the fair value on the grant date were primarily driven by changes in the stock price. Year Summary Compensation Table Total for PEO 1($) Exclusion of Stock Awards and Option Awards for PEO 1 ($) Inclusion of Equity Values for PEO 1 ($) Compensation Actually Paid to PEO 1 ($) 2023 3,049,181 (2,006,030) (1,651,770) (608,619) Year Average Summary Compensation Table Total for Non-PEO NEOs ($) Average Exclusion of Stock Awards and Option Awards for Non-PEO NEOs ($) Average Inclusion of Equity Values for Non-PEO NEOs ($) Average Compensation Actually Paid to Non-PEO NEOs ($) 2023 1,336,894 (652,850) (504,083) 179,961 The amounts in the Inclusion of Equity Values 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 1 ($) Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards for PEO 1($) Vesting-Date Fair Value of Equity Awards Granted During Year that Vested During Year for PEO 1 ($) Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year for PEO 1 ($) Fair Value at Last Day of Prior Year of Equity Awards Forfeited During Year for PEO 1 ($) Total - Inclusion of Equity Values for PEO 1 ($) 2023 595,914 (1,814,736) - (432,948) - (1,651,770) 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 at Last Day of Prior Year of Equity Awards Forfeited During Year for Non-PEO NEOs ($) Total - Average Inclusion of Equity Values for Non-PEO NEOs ($) 2023 171,167 (540,934) - (134,316) - (504,083) | | |
| Non-PEO NEO Average Total Compensation Amount | | | $ 1,336,894 | $ 1,353,832 | $ 3,075,681 |
| Non-PEO NEO Average Compensation Actually Paid Amount | | | $ 179,961 | 850,656 | 1,462,375 |
| Adjustment to Non-PEO NEO Compensation Footnote | | | The "Compensation Actually Paid" columns reflect the exclusions and inclusions of certain amounts for the PEOs and the Non-PEO NEOs as set forth below for the most recent fiscal year. Equity values are calculated in accordance with FASB ASC Topic 718. Amounts in the Exclusion of Stock Awards and Option Awards column are the totals from the Stock Awards and Option Awards columns set forth in the Summary Compensation Table. The fair values of RSUs, PSUs, and stock options included in the "Compensation Actually Paid" to our PEOs and the "Average Compensation Actually Paid" to our Non-PEO NEOs columns are calculated at the required measurement dates, consistent with the approach used to value the awards at the grant date as described in our Annual Report on Form 10-K for the year ended December 31, 2023. Any changes to the RSU and PSU fair values are based on our updated stock price at the respective measurement dates and updated performance metric projections (for PSUs). Changes to the stock option fair values are based on the updated stock price at the respective measurement dates, in addition to updated expected option life, volatility, dividend yield and risk-free rate assumptions. For all years presented, the meaningful increases or decreases in the year-end stock option fair value from the fair value on the grant date were primarily driven by changes in the stock price. Year Summary Compensation Table Total for PEO 1($) Exclusion of Stock Awards and Option Awards for PEO 1 ($) Inclusion of Equity Values for PEO 1 ($) Compensation Actually Paid to PEO 1 ($) 2023 3,049,181 (2,006,030) (1,651,770) (608,619) Year Average Summary Compensation Table Total for Non-PEO NEOs ($) Average Exclusion of Stock Awards and Option Awards for Non-PEO NEOs ($) Average Inclusion of Equity Values for Non-PEO NEOs ($) Average Compensation Actually Paid to Non-PEO NEOs ($) 2023 1,336,894 (652,850) (504,083) 179,961 The amounts in the Inclusion of Equity Values 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 1 ($) Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards for PEO 1($) Vesting-Date Fair Value of Equity Awards Granted During Year that Vested During Year for PEO 1 ($) Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year for PEO 1 ($) Fair Value at Last Day of Prior Year of Equity Awards Forfeited During Year for PEO 1 ($) Total - Inclusion of Equity Values for PEO 1 ($) 2023 595,914 (1,814,736) - (432,948) - (1,651,770) 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 at Last Day of Prior Year of Equity Awards Forfeited During Year for Non-PEO NEOs ($) Total - Average Inclusion of Equity Values for Non-PEO NEOs ($) 2023 171,167 (540,934) - (134,316) - (504,083) | | |
| Compensation Actually Paid vs. Total Shareholder Return | | | Relationship Between PEOs 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 PEOs, 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 | | | Relationship Between PEOs and Non-PEO NEO Compensation Actually Paid and Net Income The following chart sets forth the relationship between Compensation Actually Paid to our PEOs, the average of Compensation Actually Paid to our Non-PEO NEOs, and our Net Income during the three most recently completed fiscal years. | | |
| Total Shareholder Return Amount | | | $ 5.35 | 26.80 | 38.70 |
| Net Income (Loss) | | | $ (205,904,000) | (266,578,000) | (819,378,000) |
| Additional 402(v) Disclosure | | | The amounts shown for the "Compensation Actually Paid" columns have been calculated in accordance with Item 402(v) of Regulation S-K and do not reflect compensation actually earned, realized, or received by the Company’s NEOs. These amounts reflect the Summary Compensation Table Total with certain adjustments as described in footnote 3 below. On November 4, 2021, the Company completed the spin-off of 2seventy bio, Inc. All equity awards granted before January 1, 2021 were bifurcated into awards based in both Company stock and 2seventy bio, Inc. stock. The impact of this conversion has been incorporated into the calculation of Compensation Actually Paid in accordance with the methodologies disclosed in our Annual Report on Form 10-K for the year ended December 31, 2023. | | |
| Andrew Obenshain [Member] | | | | | |
| Pay vs Performance Disclosure | | | | | |
| PEO Total Compensation Amount | | | $ 3,049,181 | 1,814,700 | 9,258,001 |
| PEO Actually Paid Compensation Amount | | | $ (608,619) | $ 136,947 | 5,104,693 |
| PEO Name | Andrew Obenshain | | Andrew Obenshain | Andrew Obenshain | |
| Nick Leschly [Member] | | | | | |
| Pay vs Performance Disclosure | | | | | |
| PEO Total Compensation Amount | | | | | 7,332,683 |
| PEO Actually Paid Compensation Amount | | | | | $ 1,650,578 |
| PEO Name | | Nick Leschly | | | |
| PEO | Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table | | | | | |
| Pay vs Performance Disclosure | | | | | |
| Adjustment to Compensation, Amount | | | $ (2,006,030) | | |
| PEO | Equity Awards Adjustments, Excluding Value Reported in Compensation Table | | | | | |
| Pay vs Performance Disclosure | | | | | |
| Adjustment to Compensation, Amount | | | (1,651,770) | | |
| PEO | Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested | | | | | |
| Pay vs Performance Disclosure | | | | | |
| Adjustment to Compensation, Amount | | | 595,914 | | |
| PEO | Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested | | | | | |
| Pay vs Performance Disclosure | | | | | |
| Adjustment to Compensation, Amount | | | (1,814,736) | | |
| PEO | Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year | | | | | |
| Pay vs Performance Disclosure | | | | | |
| Adjustment to Compensation, Amount | | | 0 | | |
| PEO | Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year | | | | | |
| Pay vs Performance Disclosure | | | | | |
| Adjustment to Compensation, Amount | | | (432,948) | | |
| PEO | Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year | | | | | |
| Pay vs Performance Disclosure | | | | | |
| Adjustment to Compensation, Amount | | | 0 | | |
| Non-PEO NEO | Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table | | | | | |
| Pay vs Performance Disclosure | | | | | |
| Adjustment to Compensation, Amount | | | (652,850) | | |
| Non-PEO NEO | Equity Awards Adjustments, Excluding Value Reported in Compensation Table | | | | | |
| Pay vs Performance Disclosure | | | | | |
| Adjustment to Compensation, Amount | | | (504,083) | | |
| Non-PEO NEO | Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested | | | | | |
| Pay vs Performance Disclosure | | | | | |
| Adjustment to Compensation, Amount | | | 171,167 | | |
| Non-PEO NEO | Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested | | | | | |
| Pay vs Performance Disclosure | | | | | |
| Adjustment to Compensation, Amount | | | (540,934) | | |
| Non-PEO NEO | Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year | | | | | |
| Pay vs Performance Disclosure | | | | | |
| Adjustment to Compensation, Amount | | | 0 | | |
| Non-PEO NEO | Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year | | | | | |
| Pay vs Performance Disclosure | | | | | |
| Adjustment to Compensation, Amount | | | (134,316) | | |
| Non-PEO NEO | Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year | | | | | |
| Pay vs Performance Disclosure | | | | | |
| Adjustment to Compensation, Amount | | | $ 0 | | |
