Retirement Plans (Tables)

6 Months Ended

Mar. 31, 2016

Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]

Schedule of Net Periodic Benefit Cost

During March 2017, the Financial Accounting Standards Board issued Accounting Standards Update No. 2017-07 (“ASU 2017-07”). This amendment to GAAP will require us to exclude the components of net periodic benefit cost other than service cost from operating income on October 1, 2018, with early adoption permitted. We plan to adopt this amendment on October 1, 2017, and this adoption will require reclassification of 2017 and 2016 results. The components of net periodic benefit cost for our pension plans and the effects this adoption will have on operating income are presented below.

	Three months ended						Six months ended
	March 31,						March 31,
	2017			2016			2017			2016
	(in millions)
Service cost	$	0.5		$	0.4		$	1.0		$	0.8
Components of net periodic benefit cost that will be excluded from operating income upon adoption of ASU 2017-07:
Interest cost	3.6			5.0			7.2			10.1
Expected return on plan assets	(4.2		)	(5.1		)	(8.5		)	(10.2		)
Amortization of actuarial net loss	1.0			0.8			2.0			1.6
	0.4			0.7			0.7			1.5
Net periodic benefit cost	$	0.9		$	1.1		$	1.7		$	2.3