Revenue recognition	6 Months Ended
Revenue recognition	Jun. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenue recognition	Revenue recognition Net product sales The Company views its operations and manages its business in one operating segment. During the three months ended June 30, 2020 and 2019, net product sales in the United States were $36.2 million and $27.6 million, respectively, consisting solely of Emflaza, and net product sales not in the United States were $39.0 million and $57.8 million, respectively, consisting of Translarna and Tegsedi. For the three months ended June 30, 2020 and 2019, the Company had a total of two and two distributors, respectively, that each accounted for over 10% of the Company's net product sales. During the six months ended June 30, 2020 and 2019, net product sales in the United States were $63.6 million and $45.4 million, respectively, consisting solely of Emflaza, and net product sales not in the United States were $79.8 million and $93.0 million, respectively, consisting of Translarna and Tegsedi. For the six months ended June 30, 2020 and 2019, the Company had a total of two and two distributors, respectively, that each accounted for over 10% of the Company's net product sales. The Company’s contract liabilities balances as of June 30, 2020 and as of December 31, 2019 were $7.7 million and $11.7 million, respectively. The Company did not have any contract assets as of June 30, 2020 and as of December 31, 2019. During the three and six month periods ended June 30, 2020, the Company recognized $2.0 million and $4.0 million of revenue, respectively, related to the amounts included in the contract liability balance at the beginning of the period. For the three and six month periods ended June 30, 2019, the Company did not recognize any revenues relating to the contract liability balance at the beginning of the period. The Company has not made significant changes to the judgments made in applying ASC Topic 606 for the three and six month periods ending June 30, 2020 and 2019. Remaining performance obligations Remaining performance obligations represent the transaction price for goods the Company has yet to provide. As of June 30, 2020 and December 31, 2019, the aggregate amount of the transaction price allocated to the remaining performance obligations relating to Translarna net product revenue was $7.7 million and $11.7 million, respectively. The Company expects to recognize revenue within the next one year, as the specific timing for satisfying the performance obligations is contingent upon a number of factors, including customers’ needs and schedules. Collaboration revenue In November 2011, the Company and the Spinal Muscular Atrophy Foundation (SMA Foundation) entered into a licensing and collaboration agreement with F. Hoffman-La Roche Ltd and Hoffman- La Roche Inc. (collectively, Roche) for a spinal muscular atrophy program. Under the terms of the agreement, Roche acquired an exclusive worldwide license to the Company’s spinal muscular atrophy program. The Company is eligible to receive additional payments from Roche if specified events are achieved with respect to each licensed product, including up to $135.0 million in research and development event milestones, up to $325.0 million in sales milestones upon achievement of specified sales events, and up to double digit royalties on worldwide annual net sales of a commercial product. As of June 30, 2020, the remaining potential research and development event milestones that can be received is $72.5 million. The remaining potential sales milestones as of June 30, 2020 is $325.0 million upon achievement of certain sales events. In addition, the Company is eligible to receive up to double digit royalties on worldwide annual net sales of a commercial product. For the three months ended June 30, 2020, the Company did not recognize revenue related to the licensing and collaboration agreement with Roche. For the three months ended June 30, 2019, the Company recognized $0.1 million of revenue related to the licensing and collaboration agreement with Roche. For the six months ended June 30, 2020 and 2019, the Company recognized revenue related to the licensing and collaboration agreement with Roche of $0.1 million and $0.1 million, respectively.