Pension and Other Post-Retirement Benefits (Tables)

9 Months Ended

Sep. 30, 2018

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Components of pension and other post retirement benefit costs

	2018 Pension Benefits			2017 Pension Benefits			2018 Retiree Health and Life			2017 Retiree Health and Life
Service cost	$	6.1		$	4.9		$	0.2		$	0.1
Interest cost	11.1			11.5			0.7			0.7
Expected return on plan assets	(16.7		)	(17.9		)	—			—
Settlement expense	2.1			0.1			—			—
Amortization of (1):
Unrecognized prior service credit	—			—			(0.2		)	(0.1		)
Unrecognized net actuarial loss (gain)	7.6			6.9			—			(0.2		)
Net periodic cost	$	10.2		$	5.5		$	0.7		$	0.5

The following table shows the components of our pension and other post-retirement benefits expense for the three months ended September 30, 2018 and 2017 (in millions):

	2018 Pension Benefits			2017 Pension Benefits			2018 Retiree Health and Life			2017 Retiree Health and Life
Service cost	$	2.0		$	1.6		$	0.1		$	—
Interest cost	3.7			3.8			0.2			0.2
Expected return on plan assets	(5.6		)	(5.9		)	—			—
Settlement expense	2.1			—			—			—
Amortization of (1):
Unrecognized prior service credit	—			—			(0.1		)	—
Unrecognized net actuarial loss	2.5			2.2			—			—
Net periodic cost	$	4.7		$	1.7		$	0.2		$	0.2