Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2024

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, 2024 and 2023:

	Three months ended
	March 31,
$ in millions	2024		2023
Service cost	$	0.6	$	0.7
Interest cost	3.7		4.0
Expected return on plan assets	(3.7)		(4.4)
Amortization of unrecognized:
Prior service cost	0.3		0.2
Actuarial loss	0.5		0.2
Net periodic benefit cost	$	1.4	$	0.7

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, 2024 and 2023:

	Three months ended
	March 31,
$ in millions	2024		2023
Service cost	$	0.6	$	0.7
Interest cost	3.7		4.0
Expected return on plan assets	(3.7)		(4.4)
Amortization of unrecognized:
Prior service cost	0.2		0.3
Actuarial loss	1.0		0.3
Net periodic benefit cost	$	1.8	$	0.9