Pension and Postretirement Plans (Tables)

3 Months Ended

Mar. 31, 2021

Compensation And Retirement Disclosure [Abstract]

Schedule of Pension and Postretirement Costs (Benefits)

For the three months ended March 31, 2021 and 2020, pension and postretirement costs (benefits) were as follows:

	Three Months Ended March 31,
	2021			2020			2021			2020
(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		3.8			4.8			0.6			0.9
Expected return on plan assets		(7.5	)		(7.3	)		—			—
Amortization of:
Prior service benefit		—			—			(0.6	)		(0.6	)
Actuarial loss		6.3			4.5			—			0.2
Pension / postretirement costs	$	2.6		$	2.0		$	0.1		$	0.6