Pension Benefits and Postretirement Benefits Other Than Pensions (Tables)

6 Months Ended

Jun. 30, 2023

Pension Plans

Defined Benefit Plan Disclosure [Line Items]

Schedule of Defined Benefit Plans Disclosures

The components of Pension Expense for the Pension Plan for the six and three months ended June 30, 2023 and 2022 were:

	Six Months Ended				Three Months Ended
(Dollars in Millions)	Jun 30, 2023		Jun 30, 2022		Jun 30, 2023		Jun 30, 2022
Interest Cost on Projected Benefit Obligation	$	6.9	$	4.3	$	3.5	$	2.1
Expected Return on Plan Assets	(6.5)		(3.7)		(3.2)		(1.8)
Amortization of Prior Service Cost	0.3		0.3		0.1		0.1
Amortization of Net Actuarial Loss	—		0.9		—		0.5
Total Pension Expense	$	0.7	$	1.8	$	0.4	$	0.9

Postretirement Benefits Other than Pensions

Defined Benefit Plan Disclosure [Line Items]

Schedule of Defined Benefit Plans Disclosures

The components of OPEB Benefit for the OPEB Plans for the six and three months ended June 30, 2023 and 2022 were:

	Six Months Ended				Three Months Ended
(Dollars in Millions)	Jun 30, 2023		Jun 30, 2022		Jun 30, 2023		Jun 30, 2022
Service Cost	$	0.1	$	0.1	$	0.1	$	—
Interest Cost on Accumulated Postretirement Benefit Obligation	0.2		0.1		0.1		0.1
Amortization of Prior Service Credit	(0.7)		(0.7)		(0.4)		(0.4)
Amortization of Net Gain	(0.9)		(0.8)		(0.5)		(0.4)
Total OPEB Benefit	$	(1.3)	$	(1.3)	$	(0.7)	$	(0.7)