Pension and Postretirement Benefit Costs (Tables)

3 Months Ended

Mar. 31, 2015

Pension Plan, Defined Benefit [Member]

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

Schedule of Net Benefit Costs [Table Text Block]

Net periodic pension cost included the following components:

		Quarter Ended
		March 31,
		2015			2014
	(Dollars in millions)
Service cost for benefits earned		$	0.6		$	0.5
Interest cost on projected benefit obligation		10.1			11.3
Expected return on plan assets		(12.0		)	(13.5		)
Amortization of prior service cost and net actuarial loss		10.2			7.9
Net periodic pension cost		$	8.9		$	6.2

Other Postretirement Benefit Plan, Defined Benefit [Member]

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

Schedule of Net Benefit Costs [Table Text Block]

Net periodic postretirement benefit cost included the following components:

		Quarter Ended
		March 31,
		2015		2014
	(Dollars in millions)
Service cost for benefits earned		$	2.8	$	3.1
Interest cost on accumulated postretirement benefit obligation		8.5		9.1
Amortization of prior service cost and net actuarial loss		4.5		3.9
Net periodic postretirement benefit cost		$	15.8	$	16.1