Retirement Plans (Tables)

6 Months Ended

Mar. 31, 2020

Retirement Plans [Abstract]

Summary of Components of Net Pension Income and Summary of Components of Postretirement Benefit Cost

Pension and Postretirement Income / Expense

The following table presents a summary of the components of net pension income (in millions):

	Three Months Ended						Six Months Ended
	March 31,						March 31,
	2020			2019			2020			2019
Service cost	$	14.2		$	11.4		$	27.3		$	22.3
Interest cost		49.5			58.7			99.4			115.2
Expected return on plan assets		(90.8	)		(85.9	)		(181.6	)		(168.8	)
Amortization of net actuarial loss		11.8			5.4			23.7			12.4
Amortization of prior service cost		2.1			1.3			3.5			2.6
Curtailment loss		0.4			0.9			0.4			0.9
Company defined benefit plan income		(12.8	)		(8.2	)		(27.3	)		(15.4	)
Multiemployer and other plans		0.4			0.1			0.7			0.3
Net pension income	$	(12.4	)	$	(8.1	)	$	(26.6	)	$	(15.1	)

The following table presents a summary of the components of the net postretirement cost (in millions):

	Three Months Ended						Six Months Ended
	March 31,						March 31,
	2020			2019			2020			2019
Service cost	$	0.3		$	0.3		$	0.7		$	0.6
Interest cost		1.8			2.0			3.6			3.9
Amortization of net actuarial gain		(0.2	)		(0.4	)		(0.4	)		(0.8	)
Amortization of prior service credit		(0.7	)		(0.7	)		(1.4	)		(1.4	)
Net postretirement cost	$	1.2		$	1.2		$	2.5		$	2.3