Defined Contribution Plan

12 Months Ended

Dec. 31, 2017

Defined Contribution Plan

16. Defined Contribution Plan

We have established a 401(k) plan that permits participants to make contributions by salary reduction, and we match these contributions up to a predefined threshold. During the years ended December 31, 2017, 2016 and 2015, compensation expense associated with our matching contribution was $0.4 million, $0.3 million and $0.2 million, respectively.