Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2023

Entity Information [Line Items]

Schedule of Net Periodic Benefit Cost / (Income)

The following table presents the net periodic benefit cost of the Pension Plans for the three months ended March 31, 2023 and 2022:

	Three months ended
	March 31,
$ in millions	2023		2022
Service cost	$	0.7	$	1.3
Interest cost	4.0		2.4
Expected return on plan assets	(4.4)		(4.0)
Amortization of unrecognized:
Prior service cost	0.2		0.2
Actuarial loss	0.2		1.4
Net periodic benefit cost	$	0.7	$	1.3

Subsidiaries [Member]

Entity Information [Line Items]

Schedule of Net Periodic Benefit Cost / (Income)

The following table presents the net periodic benefit cost of the Pension Plans for the three months ended March 31, 2023 and 2022:

	Three months ended
	March 31,
$ in millions	2023		2022
Service cost	$	0.7	$	1.3
Interest cost	4.0		2.4
Expected return on plan assets	(4.4)		(4.0)
Amortization of unrecognized:
Prior service cost	0.3		0.3
Actuarial loss	0.3		1.9
Net periodic benefit cost	$	0.9	$	1.9