Employee Benefit Plans

3 Months Ended

Mar. 31, 2023

Retirement Benefits [Abstract]

Employee Benefit Plans

8. Employee Benefit Plans

The components of net periodic cost (gain) for our defined benefit pension plan and for our postretirement benefit plan are included in the following tables:

	Three Months Ended March 31,
	2023			2022
Net Periodic Pension Cost	(Dollars in millions)
Interest cost	$	4.3		$	2.2
Actuarial loss amortization		2.1			3.4
Less: Expected return on plan assets		(5.5	)		(3.9	)
Net periodic pension cost	$	0.9		$	1.7

	Three Months Ended March 31,
	2023			2022
Net Periodic Postretirement Benefit	(Dollars in millions)
Interest cost	$	0.1		$	—
Actuarial gain amortization		(0.6	)		(0.5	)
Net periodic postretirement benefit gain	$	(0.5	)	$	(0.5	)