Employee Benefit Plans

6 Months Ended

Jun. 30, 2016

Compensation and Retirement Disclosure [Abstract]

Employee Benefit Plans

Employee Benefit Plans

We have defined benefit pension plans for our U.K.-based union employees (the "U.K. Plan") and certain Canadian-based employees (the "Canadian Plan"). Retirement benefits under the U.K. Plan are generally based on an employee's average compensation over the two years preceding retirement. Retirement benefits under the Canadian Plan are generally based on the number of years of credited service. Our policy is to fund the minimum contribution permissible by the applicable authorities. See Note 19 (Pension and Other Post Retirement Plans) in our 2015 Annual Report on Form 10-K.

The net periodic benefit cost recognized for both the three months ended June 30, 2016 and 2015 was $0.4 million. The net periodic benefit cost recognized for the six months ended June 30, 2016 and 2015 was $0.7 million and $0.9 million, respectively.

We have a 401(k) plan for U.S.-based employees. Those employees who participate in our 401(k) plan are eligible to receive matching contributions of 35% from us for participant contributions up to the first 6% of their compensation (as defined in the plan document). Contribution expense for the three months ended June 30, 2016 and 2015 was $2.9 million and $2.7 million, respectively. Contribution expense for the six months ended June 30, 2016 and 2015 was $5.8 million and $5.8 million, respectively.