Commitments and Contingencies	3 Months Ended
Mar. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies The Company was a party to a master services agreement (“MSA”) with Cornell University (“Cornell”) originally established in August 2014 and amended in December 2015. Under the MSA, Cornell provided assistance in regulatory affairs, overall project management, and parameter development. The MSA, as amended, provided for the Company to pay Cornell $13.3 million ratably over four years for these services as services were performed. In December 2016, the Company informed Cornell that the Company decided to terminate the MSA for material breach, effective January 6, 2017. Subsequently, Cornell informed the Company that it disputes the validity of the Company’s termination of the MSA. Although the Company intends to defend the validity of the termination of the MSA, the Company recorded $2.0 million of estimated costs associated with the termination of the MSA during the year ended December 31, 2017. This MSA included services relating to gene therapy programs directed to A1AT deficiency, HAE and severe allergy. The Company’s license agreements with Cornell remained in effect despite the termination of the MSA. Legal Proceedings From time to time, the Company may become involved in litigation and other legal actions. The Company estimates the range of liability related to any pending litigation where the amount and range of loss can be estimated. The Company records its best estimate of a loss when the loss is considered probable. Where a liability is probable and there is a range of estimated loss with no best estimate in the range, the Company records a charge equal to at least the minimum estimated liability for a loss contingency when both of the following conditions are met: (i) information available prior to issuance of the financial statements indicates that it is probable that a liability had been incurred at the date of the financial statements and (ii) the range of loss can be reasonably estimated. There have been no material changes from the legal proceedings described in our annual report on Form 10-K for the period ended December 31, 2018.

Commitments and Contingencies

3 Months Ended

Mar. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

7. Commitments and Contingencies

The Company was a party to a master services agreement (“MSA”) with Cornell University (“Cornell”) originally established in August 2014 and amended in December 2015. Under the MSA, Cornell provided assistance in regulatory affairs, overall project management, and parameter development. The MSA, as amended, provided for the Company to pay Cornell $13.3 million ratably over four years for these services as services were performed. In December 2016, the Company informed Cornell that the Company decided to terminate the MSA for material breach, effective January 6, 2017. Subsequently, Cornell informed the Company that it disputes the validity of the Company’s termination of the MSA. Although the Company intends to defend the validity of the termination of the MSA, the Company recorded $2.0 million of estimated costs associated with the termination of the MSA during the year ended December 31, 2017. This MSA included services relating to gene therapy programs directed to A1AT deficiency, HAE and severe allergy. The Company’s license agreements with Cornell remained in effect despite the termination of the MSA.

Legal Proceedings

From time to time, the Company may become involved in litigation and other legal actions. The Company estimates the range of liability related to any pending litigation where the amount and range of loss can be estimated. The Company records its best estimate of a loss when the loss is considered probable. Where a liability is probable and there is a range of estimated loss with no best estimate in the range, the Company records a charge equal to at least the minimum estimated liability for a loss contingency when both of the following conditions are met: (i) information available prior to issuance of the financial statements indicates that it is probable that a liability had been incurred at the date of the financial statements and (ii) the range of loss can be reasonably estimated.

There have been no material changes from the legal proceedings described in our annual report on Form 10-K for the period ended December 31, 2018.