Employee Retirement Plan

12 Months Ended

Dec. 31, 2017

Compensation And Retirement Disclosure [Abstract]

Employee Retirement Plan

11. Employee Retirement Plan

During 2008, the Company established a retirement plan (the Plan) authorized by Section 401(k) of the Internal Revenue Code. In accordance with the Plan, all employees who have attained the age of 21 are eligible to participate in the Plan as of the first Entry Date, as defined, following their date of employment. Each employee can contribute a percentage of compensation up to a maximum of the statutory limits per year. Company contributions are discretionary and contributions in the amount of approximately $0.2 million, $0.2 million and $0.1 million were made during the years ended December 31, 2017, 2016 and 2015, respectively.