Equity-Method Investment	12 Months Ended
Dec. 31, 2022
Equity Method Investments and Joint Ventures [Abstract]
Equity-Method Investment	10. Equity-Method Investment and Other Investments AvenCell Therapeutics, Inc. On July 30, 2021, the Company finalized a transaction in which the Company, Cellex and BXLS established AvenCell, a joint venture and privately held company. In exchange for contributing an exclusive license to the joint venture, the Company entered into a Preferred Stock Purchase Agreement with AvenCell for a 33.33% equity interest in AvenCell at the time of the initial closing. Cellex and BXLS each equally owned the remaining 66.67% at that time. The Company has significant influence over, but does not control, AvenCell through its noncontrolling representation on AvenCell’s Board of Directors and the Company’s equity interest in AvenCell. The Company has determined that the preferred stock it owns is in-substance common stock. The Company is not the primary beneficiary as it does not have the power to direct the activities of AvenCell that most significantly impact AvenCell’s economic performance. Accordingly, the Company does not consolidate the financial statements of AvenCell and accounts for its investment using the equity method of accounting. As of the closing date, the fair value of the Company’s investment in AvenCell was $62.9 million which represents the fair value of the preferred stock received in exchange for the exclusive license to the Company’s CRISPR/Cas9 allogeneic platform (See Note 9). In determining the fair value of the Company’s investment, the Company used an option pricing model which requires the input of certain subjective assumptions. The key assumptions used in the option pricing model, which are level 3 inputs, include the anticipated holding period to an exit and liquidity event, the volatility of market participants (76%), the probability of AvenCell achieving certain milestones to obtain subsequent financings (75%) and the discount for lack of marketability (11%). The Company recorded the initial investment in AvenCell of $62.9 million in “Equity method investments” on its consolidated balance sheet. Due to the timing and availability of AvenCell's financial information, the Company is recording its share of losses from AvenCell on a quarterly basis on a one-quarter lag. Therefore, the Company recorded its share of twelve months of AvenCell’s losses generated in the fourth quarter of 2021 and the first three quarters of 2022 in the Company's operating results and other comprehensive loss for the year ended December 31, 2022, resulting in a reduction of the Company's investment by $14.3 million. The Company recorded its share of two months of AvenCell's losses generated in the third quarter of 2021 in the Company's operating results and other comprehensive loss in the fourth quarter of 2021, resulting in a reduction of the Company's investment by $1.8 million. The elimination of the intra-entity profit component of $11.4 million and $2.9 million for the years ended December 31, 2022 and 2021, respectively (See Note 9) resulted in a further reduction in the balance of the investment in AvenCell, bringing the carrying value of the investment to $32.5 million and $58.1 million as of December 31, 2022 and 2021, respectively. The Company is not aware of any material events or transactions during this period that would warrant additional disclosure or recognition in the financial statements. At December 31, 2022, the maximum exposure to loss is limited to the Company’s equity investment in the joint venture. SparingVision SAS In connection with the SparingVision LCA (See Note 9), the Company received 83,316 shares of Series A2 Preferred Stock (“Series A2”). Attached to each share of Series A2, the Company received three warrants for the right to purchase additional Series A2 shares at designated prices that are subject to certain vesting conditions (collectively referred to as the “SparingVision investments”). The Company accounts for the SparingVision investments using the measurement alternative as SparingVision is a private company and there is no readily observable transaction price. In determining the fair value of the SparingVision investments, the Company used an option pricing model which requires the input of certain subjective assumptions. The key assumptions used in the option pricing model, which are level 3 inputs, include the anticipated holding period to an exit and liquidity event, the volatility of market participants (90%), and the rate of return (65%). The Company recorded the initial investment in SparingVision of $14.8 million in “Investments and other assets” on its consolidated balance sheet. There was no change in the observable price or impairment of the SparingVision investment as of December 31, 2022 or 2021. Kyverna Therapeutics, Inc. In connection with the Kyverna LCA (See Note 9), the Company received 3,739,515 shares of Series B Preferred Stock with a fair value of $7.0 million. The Company separately made an additional investment in Kyverna, purchasing 1,602,649 shares of Series B Preferred Stock in exchange for $3.0 million in cash (collectively referred to as the “Kyverna investment”). The Company accounts for the Kyverna investment using the measurement alternative as Kyverna is a private company and there is no readily observable transaction price. The Company recorded the initial investment in Kyverna of $10.0 million in “Investments and other assets” on its consolidated balance sheet. There was no change in the observable price or impairment of the Kyverna investment as of December 31, 2022 or 2021.

Equity-Method Investment

12 Months Ended

Dec. 31, 2022

Equity Method Investments and Joint Ventures [Abstract]

10.

Equity-Method Investment and Other Investments

AvenCell Therapeutics, Inc.

On July 30, 2021, the Company finalized a transaction in which the Company, Cellex and BXLS established AvenCell, a joint venture and privately held company. In exchange for contributing an exclusive license to the joint venture, the Company entered into a Preferred Stock Purchase Agreement with AvenCell for a 33.33% equity interest in AvenCell at the time of the initial closing. Cellex and BXLS each equally owned the remaining 66.67% at that time.

The Company has significant influence over, but does not control, AvenCell through its noncontrolling representation on AvenCell’s Board of Directors and the Company’s equity interest in AvenCell. The Company has determined that the preferred stock it owns is in-substance common stock. The Company is not the primary beneficiary as it does not have the power to direct the activities of AvenCell that most significantly impact AvenCell’s economic performance. Accordingly, the Company does not consolidate the financial statements of AvenCell and accounts for its investment using the equity method of accounting.

As of the closing date, the fair value of the Company’s investment in AvenCell was $62.9 million which represents the fair value of the preferred stock received in exchange for the exclusive license to the Company’s CRISPR/Cas9 allogeneic platform (See Note 9). In determining the fair value of the Company’s investment, the Company used an option pricing model which requires the input of certain subjective assumptions. The key assumptions used in the option pricing model, which are level 3 inputs, include the anticipated holding period to an exit and liquidity event, the volatility of market participants (76%), the probability of AvenCell achieving certain milestones to obtain subsequent financings (75%) and the discount for lack of marketability (11%).

The Company recorded the initial investment in AvenCell of $62.9 million in “Equity method investments” on its consolidated balance sheet. Due to the timing and availability of AvenCell's financial information, the Company is recording its share of losses from AvenCell on a quarterly basis on a one-quarter lag. Therefore, the Company recorded its share of twelve months of AvenCell’s losses generated in the fourth quarter of 2021 and the first three quarters of 2022 in the Company's operating results and other comprehensive loss for the year ended December 31, 2022, resulting in a reduction of the Company's investment by $14.3 million. The Company recorded its share of two months of AvenCell's losses generated in the third quarter of 2021 in the Company's operating results and other comprehensive loss in the fourth quarter of 2021, resulting in a reduction of the Company's investment by $1.8 million. The elimination of the intra-entity profit component of $11.4 million and $2.9 million for the years ended December 31, 2022 and 2021, respectively (See Note 9) resulted in a further reduction in the balance of the investment in AvenCell, bringing the carrying value of the investment to $32.5 million and $58.1 million as of December 31, 2022 and 2021, respectively. The Company is not aware of any material events or transactions during this period that would warrant additional disclosure or recognition in the financial statements.

At December 31, 2022, the maximum exposure to loss is limited to the Company’s equity investment in the joint venture.

SparingVision SAS

In connection with the SparingVision LCA (See Note 9), the Company received 83,316 shares of Series A2 Preferred Stock (“Series A2”). Attached to each share of Series A2, the Company received three warrants for the right to purchase additional Series A2 shares at designated prices that are subject to certain vesting conditions (collectively referred to as the “SparingVision investments”). The Company accounts for the SparingVision investments using the measurement alternative as SparingVision is a private company and there is no readily observable transaction price. In determining the fair value of the SparingVision investments, the Company used an option pricing model which requires the input of certain subjective assumptions. The key assumptions used in the option pricing model, which are level 3 inputs, include the anticipated holding period to an exit and liquidity event, the volatility of market participants (90%), and the rate of return (65%). The Company recorded the initial investment in SparingVision of $14.8 million in “Investments and other assets” on its consolidated balance sheet. There was no change in the observable price or impairment of the SparingVision investment as of December 31, 2022 or 2021.

Kyverna Therapeutics, Inc.

In connection with the Kyverna LCA (See Note 9), the Company received 3,739,515 shares of Series B Preferred Stock with a fair value of $7.0 million. The Company separately made an additional investment in Kyverna, purchasing 1,602,649 shares of Series B Preferred Stock in exchange for $3.0 million in cash (collectively referred to as the “Kyverna investment”). The Company accounts for the Kyverna investment using the measurement alternative as Kyverna is a private company and there is no readily observable transaction price. The Company recorded the initial investment in Kyverna of $10.0 million in “Investments and other assets” on its consolidated balance sheet. There was no change in the observable price or impairment of the Kyverna investment as of December 31, 2022 or 2021.