Retirement Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2018

Compensation And Retirement Disclosure [Abstract]

Components of Net Periodic Pension Expense

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,
	2018			2017
Service cost	$	7.5		$	7.5
Interest cost		5.5			4.7
Expected return on plan assets		(11.8	)		(10.1	)
Amortization of prior service cost		(2.5	)		(2.6	)
Amortization of unrecognized actuarial loss		6.1			5.6
Net periodic pension expense	$	4.8		$	5.1