Employee Benefit Plan

12 Months Ended

Dec. 31, 2016

Employee Benefit Plan [Abstract]

Employee Benefit Plan

9.  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. Beginning in 2005 the Company made contributions at a rate of 25% of the first 4% of employee compensation contributed. Starting on January 1, 2014, the Company began making contributions at a rate of 50% on an additional 2% of contributions made by employees, up to 6%. As a result, the Company was matching 25% of the first 4% of employee contributions and 50% of employee contributions between 4% and 6% during 2014. Starting on January 1, 2015, the Company revised its contribution structure, and during 2015 was matching 50% of the first 6% of contributions made by employees. Starting on January 1, 2016, the Company revised its contribution structure, and during 2016 was matching 100% of the first 1% of contributions and 50% of the next 5% of contributions made by employees. The Company contributed $2.5 million, $1.3 million and $0.6 million to the 401(k) Plan for the years ended December 31, 2016, 2015 and 2014, respectively.