Employee Benefit Plan

12 Months Ended

Dec. 31, 2017

Employee Benefit Plan [Abstract]

Employee Benefit Plan

10. Employee Benefit Plan

The Company sponsors a defined contribution 401(k) retirement plan covering all eligible employees.

Qualified employees may elect to contribute to the 401(k) Plan on a pre-tax basis. The maximum amount of employee contribution is subject only to statutory limitations. Starting on January 1, 2015, the Company matched 50% of the first 6% of contributions made by employees. Since January 1, 2016, the Company has matched 100% of the first 1% of contributions and 50% of the next 5% of contributions made by employees. The Company contributed $2.6 million, $2.5 million and $1.3 million to the 401(k) Plan for the years ended December 31, 2017, 2016 and 2015, respectively.