Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2025

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, 2025 and 2024:

	Three months ended
	March 31,
$ in millions	2025		2024
Service cost	$	0.6	$	0.6
Interest cost	3.6		3.7
Expected return on plan assets	(3.9)		(3.7)
Amortization of unrecognized:
Prior service cost	0.2		0.3
Actuarial loss	0.8		0.5
Net periodic benefit cost	$	1.3	$	1.4

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, 2025 and 2024:

	Three months ended
	March 31,
$ in millions	2025		2024
Service cost	$	0.6	$	0.6
Interest cost	3.6		3.7
Expected return on plan assets	(3.9)		(3.7)
Amortization of unrecognized:
Prior service cost	0.2		0.2
Actuarial loss	1.3		1.0
Net periodic benefit cost	$	1.8	$	1.8