Retirement Benefit Plans

3 Months Ended

Mar. 31, 2017

Compensation and Retirement Disclosure [Abstract]

Retirement Benefit Plans

12. Retirement Benefit Plans

We have defined benefit pension plans covering certain U.S. and Puerto Rico employees. The employees who are not participating in the defined benefit plans receive additional benefits under our defined contribution plans. Plan benefits are primarily based on years of credited service and the participant’s compensation. In addition to the U.S. and Puerto Rico defined benefit pension plans, we sponsor various foreign pension arrangements, including retirement and termination benefit plans required by local law or coordinated with government sponsored plans.

The components of net periodic pension expense for our U.S. and foreign defined benefit pension plans are as follows (in millions):

	Three Months Ended March 31,
	2017			2016
Service cost	$	7.5		$	7.5
Interest cost		4.7			7.2
Expected return on plan assets		(10.1	)		(12.7	)
Curtailment gain		—			(0.3	)
Amortization of prior service cost		(2.6	)		(1.9	)
Amortization of unrecognized actuarial loss		5.6			5.0
Net periodic pension expense	$	5.1		$	4.8

We expect that we will have minimal legally required funding obligations in 2017 for our U.S. and Puerto Rico defined benefit pension plans, and therefore we have not made, nor do we voluntarily expect to make, any material contributions to these plans during 2017. We contributed $4.1 million to our foreign-based defined benefit pension plans in the three month period ended March 31, 2017, and we expect to contribute $12.5 million to these foreign-based plans during the remainder of 2017.