Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2020

Entity Information [Line Items]

Schedule of Net Periodic Benefit Cost / (Income)

The net periodic benefit cost of the pension benefit plans for the three and nine months ended September 30, 2020 and 2019 was:

	Three months ended				Nine months ended
	September 30,				September 30,
$ in millions	2020		2019		2020		2019
Service cost	$	0.9	$	0.9	$	2.8	$	2.7
Interest cost	2.9		3.7		8.8		11.2
Expected return on plan assets	(4.6)		(5.0)		(14.0)		(15.0)
Amortization of unrecognized:
Prior service cost	0.3		0.3		0.8		0.9
Actuarial loss	1.5		1.1		4.6		3.2
Net periodic benefit cost	$	1.0	$	1.0	$	3.0	$	3.0

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 and nine months ended September 30, 2020 and 2019 was:

	Three months ended				Nine months ended
	September 30,				September 30,
$ in millions	2020		2019		2020		2019
Service cost	$	0.9	$	0.9	$	2.8	$	2.7
Interest cost	2.9		3.7		8.8		11.2
Expected return on plan assets	(4.6)		(5.0)		(14.0)		(15.0)
Amortization of unrecognized:
Prior service cost	0.3		0.4		1.0		1.3
Actuarial loss	2.2		1.8		6.5		5.3
Net periodic benefit cost	$	1.7	$	1.8	$	5.1	$	5.5