Benefit Plans (Tables)

9 Months Ended

Sep. 30, 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 and nine months ended September 30, 2023 and 2022:

	Three months ended				Nine months ended
	September 30,				September 30,
$ in millions	2023		2022		2023		2022
Service cost	$	0.8	$	1.2	$	2.2	$	3.7
Interest cost	3.9		2.4		11.9		7.2
Expected return on plan assets	(4.4)		(4.0)		(13.2)		(11.9)
Amortization of unrecognized:
Prior service cost	0.3		0.3		0.8		0.8
Actuarial loss	0.2		1.4		0.5		4.1
Net periodic benefit cost	$	0.8	$	1.3	$	2.2	$	3.9

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 and nine months ended September 30, 2023 and 2022:

	Three months ended				Nine months ended
	September 30,				September 30,
$ in millions	2023		2022		2023		2022
Service cost	$	0.8	$	1.2	$	2.2	$	3.7
Interest cost	3.9		2.4		11.9		7.2
Expected return on plan assets	(4.4)		(4.0)		(13.2)		(11.9)
Amortization of unrecognized:
Prior service cost	0.2		0.3		0.8		0.9
Actuarial loss	0.3		2.0		0.9		5.8
Net periodic benefit cost	$	0.8	$	1.9	$	2.6	$	5.7