Pensions and Other Postretirement Benefits (Tables)

6 Months Ended

Oct. 31, 2016

Compensation and Retirement Disclosure [Abstract]

Net periodic benefit cost

The components of our net periodic benefit cost for defined benefit pension and other postretirement benefit plans are shown below.

	Three Months Ended October 31,
	Defined Benefit Pension Plans						Other Postretirement Benefits
	2016			2015			2016			2015
Service cost	$	3.6		$	4.4		$	0.6		$	0.5
Interest cost	6.2			6.9			0.6			0.7
Expected return on plan assets	(7.3		)	(8.3		)	—			—
Recognized net actuarial loss (gain)	3.4			2.7			(0.1		)	(0.1		)
Prior service cost (credit)	0.3			0.2			(0.3		)	(0.2		)
Curtailment gain	—			(0.8		)	—			(0.1		)
Net periodic benefit cost	$	6.2		$	5.1		$	0.8		$	0.8

	Six Months Ended October 31,
	Defined Benefit Pension Plans						Other Postretirement Benefits
	2016			2015			2016			2015
Service cost	$	7.7		$	9.1		$	1.2		$	1.1
Interest cost	12.9			13.9			1.3			1.4
Expected return on plan assets	(14.6		)	(16.7		)	—			—
Recognized net actuarial loss (gain)	7.1			5.4			(0.1		)	(0.1		)
Prior service cost (credit)	0.6			0.4			(0.7		)	(0.5		)
Curtailment gain	—			(4.5		)	—			(0.1		)
Settlement loss	0.1			—			—			—
Net periodic benefit cost	$	13.8		$	7.6		$	1.7		$	1.8