Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2022

Entity Information [Line Items]

Schedule of Net Periodic Benefit Cost / (Income)

The net periodic benefit cost of the pension benefit plans for the three months ended March 31, 2022 and 2021 was:

	Three months ended
	March 31,
$ in millions	2022		2021
Service cost	$	1.3	$	1.1
Interest cost	2.4		2.0
Expected return on plan assets	(4.0)		(3.7)
Amortization of unrecognized:
Prior service cost	0.2		0.2
Actuarial loss	1.4		2.3
Net periodic benefit cost	$	1.3	$	1.9

Subsidiaries [Member]

Entity Information [Line Items]

Schedule of Net Periodic Benefit Cost / (Income)

The net periodic benefit cost of the pension benefit plans for the three months ended March 31, 2022 and 2021 was:

	Three months ended
	March 31,
$ in millions	2022		2021
Service cost	$	1.3	$	1.1
Interest cost	2.4		2.0
Expected return on plan assets	(4.0)		(3.7)
Amortization of unrecognized:
Prior service cost	0.3		0.3
Actuarial loss	1.9		2.8
Net periodic benefit cost	$	1.9	$	2.5