Property, Plant and Equipment (Tables)

9 Months Ended

Sep. 30, 2018

Property, Plant and Equipment [Line Items]

Schedule of Change in Asset Retirement Obligation [Table Text Block]

Changes in the Liability for AROs

$ in millions
Balance at January 1, 2018	$	15.1
Revisions to cash flow and timing estimates	1.6
Accretion expense	0.2
Settlements	(3.4		)
Balance at September 30, 2018	$	13.5

See Note 5 – Fair Value for further discussion on changes to our AROs.

Subsidiaries [Member]

Property, Plant and Equipment [Line Items]

Schedule of Change in Asset Retirement Obligation [Table Text Block]

Changes in the Liability for AROs

$ in millions
Balance at January 1, 2018	$	8.0
Revisions to cash flow and timing estimates	0.1
Settlements	(3.4		)
Balance at September 30, 2018	$	4.7