Subsequent Event	3 Months Ended
Mar. 31, 2021
Subsequent Events [Abstract]
Subsequent Event	12. Subsequent Event In April 2021, the Company entered into an Option, License and Collaboration Agreement (“Vivet Collaboration Agreement”) with Vivet Therapeutics SAS (“Vivet”). Pursuant to the Vivet Collaboration Agreement, Vivet granted the Company the exclusive option to develop and subsequently commercialize Vivet’s two proprietary AAV gene therapy programs for PFIC, subtypes 3 and 2. Under the terms of the Vivet Collaboration Agreement, the Company agreed to provide funding to support certain research and development costs associated with the two gene therapy programs. Pursuant to the Vivet Collaboration Agreement, the Company paid an upfront fee of €3.5 million and initial research and development funding of €5.3 million ($4.2 million and $6.4 million, respectively, based on the exchange rate in effect at the time of payment). In April 2021, the Company entered into an exclusive licensing agreement with CANbridge Pharmaceuticals (“CANbridge”). Under the terms of the agreement, CANbridge has obtained the exclusive right to develop and commercialize maralixibat within the Greater China regions (China, Hong Kong, Macau and Taiwan) for ALGS, PFIC, and biliary atresia. The Company is entitled to receive an $11.0 million upfront payment, research and development funding, and up to $109.0 million for the achievement of future regulatory and commercial maralixibat milestones, with significant double-digit tiered royalties based on product net sales.

Subsequent Event

3 Months Ended

Mar. 31, 2021

12. Subsequent Event

In April 2021, the Company entered into an Option, License and Collaboration Agreement (“Vivet Collaboration Agreement”) with Vivet Therapeutics SAS (“Vivet”). Pursuant to the Vivet Collaboration Agreement, Vivet granted the Company the exclusive option to develop and subsequently commercialize Vivet’s two proprietary AAV gene therapy programs for PFIC, subtypes 3 and 2. Under the terms of the Vivet Collaboration Agreement, the Company agreed to provide funding to support certain research and development costs associated with the two gene therapy programs.

Pursuant to the Vivet Collaboration Agreement, the Company paid an upfront fee of €3.5 million and initial research and development funding of €5.3 million ($4.2 million and $6.4 million, respectively, based on the exchange rate in effect at the time of payment).

In April 2021, the Company entered into an exclusive licensing agreement with CANbridge Pharmaceuticals (“CANbridge”). Under the terms of the agreement, CANbridge has obtained the exclusive right to develop and commercialize maralixibat within the Greater China regions (China, Hong Kong, Macau and Taiwan) for ALGS, PFIC, and biliary atresia. The Company is entitled to receive an $11.0 million upfront payment, research and development funding, and up to $109.0 million for the achievement of future regulatory and commercial maralixibat milestones, with significant double-digit tiered royalties based on product net sales.