Related Party Transactions	12 Months Ended
Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	15. Related Party Transactions Casebia During the years ended December 31, 2018, 2017 and 2016 the Company recognized revenue of $2.5 million, $4.8 million and $1.2 million, respectively, related to the collaboration with Casebia. During the years ended December 31, 2018, 2017 and 2016 the Company recognized research and development expense of $3.8 million, $4.5 million and $1.7 million, respectively, related to the performance of services for Casebia. The Company and Casebia have engaged several research institutions and companies to identify new delivery strategies and applications of the gene-editing technology. Additionally, the Company and Casebia are also a party to a number of research license agreements. The Company and Casebia will share costs associated with the research and license agreements. Under both research and license agreements, the Company received reimbursements of $0.9 million, $4.4 million during 2018 and 2017, respectively. There were no reimbursements recorded during 2016. The reimbursements were recorded as a reduction of R&D expense in the income statement. Vertex In 2018, upon becoming owners of record of more than 10% of the voting interest of the Company, Vertex became a related party under ASC 850, Related party disclosures. During the year ended December 31, 2018, the Company recognized revenue of $0.6 million related to the collaboration with Vertex. During the year ended December 31, 2018, the Company recognized research and development expense of $20.2 million, related to the performance of services under the collaboration with Vertex, which is net of $13.8 million of reimbursements from Vertex.

Related Party Transactions

12 Months Ended

Dec. 31, 2018

15. Related Party Transactions

Casebia

During the years ended December 31, 2018, 2017 and 2016 the Company recognized revenue of $2.5 million, $4.8 million and $1.2 million, respectively, related to the collaboration with Casebia. During the years ended December 31, 2018, 2017 and 2016 the Company recognized research and development expense of $3.8 million, $4.5 million and $1.7 million, respectively, related to the performance of services for Casebia. The Company and Casebia have engaged several research institutions and companies to identify new delivery strategies and applications of the gene-editing technology. Additionally, the Company and Casebia are also a party to a number of research license agreements. The Company and Casebia will share costs associated with the research and license agreements. Under both research and license agreements, the Company received reimbursements of $0.9 million, $4.4 million during 2018 and 2017, respectively. There were no reimbursements recorded during 2016. The reimbursements were recorded as a reduction of R&D expense in the income statement.

Vertex

In 2018, upon becoming owners of record of more than 10% of the voting interest of the Company, Vertex became a related party under ASC 850, Related party disclosures. During the year ended December 31, 2018, the Company recognized revenue of $0.6 million related to the collaboration with Vertex. During the year ended December 31, 2018, the Company recognized research and development expense of $20.2 million, related to the performance of services under the collaboration with Vertex, which is net of $13.8 million of reimbursements from Vertex.