Pension and Postretirement Plans (Tables)

3 Months Ended

Mar. 31, 2018

Retirement Benefits, Description [Abstract]

Schedule of Net Benefit Costs [Table Text Block]

For the three months ended March 31, 2018 and 2017, pension and postretirement benefit costs (benefits) were as follows:

	Three Months Ended March 31,
	2018			2017			2018			2017
(dollars in millions)	Pension Benefits						Postretirement and Other Benefits
Service cost	$	—		$	—		$	0.1		$	0.1
Other components of pension and postretirement benefit plans expense:
Interest cost on projected benefit obligation	4.2			4.8			0.8			0.8
Expected return on plan assets	(6.2		)	(6.5		)	—			—
Amortization of:
Prior service benefit	—			—			(0.8		)	(1.1		)
Actuarial loss	4.3			4.4			1.0			1.1
Total amortization	4.3			4.4			0.2			—
Pension / postretirement costs	$	2.3		$	2.7		$	1.1		$	0.9