Pensions and Other Postretirement Benefits (Tables)

6 Months Ended

Oct. 31, 2018

Retirement Benefits [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
	2018			2017			2018			2017
Service cost	$	0.5		$	1.7		$	0.5		$	0.5
Interest cost	5.8			5.4			0.6			0.6
Expected return on plan assets	(6.7		)	(7.2		)	—			—
Amortization of net actuarial loss (gain)	2.1			2.8			(0.2		)	(0.1		)
Amortization of prior service cost (credit)	0.3			0.3			(0.3		)	(0.4		)
Net periodic benefit cost	$	2.0		$	3.0		$	0.6		$	0.6

	Six Months Ended October 31,
	Defined Benefit Pension Plans						Other Postretirement Benefits
	2018			2017			2018			2017
Service cost	$	1.1		$	3.4		$	0.9		$	1.0
Interest cost	11.7			10.8			1.2			1.1
Expected return on plan assets	(13.5		)	(14.4		)	—			—
Amortization of net actuarial loss (gain)	4.1			5.7			(0.3		)	(0.2		)
Amortization of prior service cost (credit)	0.5			0.5			(0.6		)	(0.7		)
Net periodic benefit cost	$	3.9		$	6.0		$	1.2		$	1.2