Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2022

Related Party Transaction [Line Items]

Schedule of Accumulated Other Comprehensive Income (Loss)

The changes in the components of Accumulated other comprehensive loss during the three months ended March 31, 2022 are as follows:

$ in millions	Change in cash flow hedges		Change in unfunded pension and postretirement benefit obligations		Total
Balance as of January 1, 2022	$	12.8	$	(17.6)	$	(4.8)
Amounts reclassified from AOCL to earnings	(0.1)		0.2		0.1
Net current period other comprehensive income / (loss)	(0.1)		0.2		0.1
Balance as of March 31, 2022	$	12.7	$	(17.4)	$	(4.7)

Reclassification out of Accumulated Other Comprehensive Income

The amounts reclassified out of Accumulated other comprehensive loss by component during the three months ended March 31, 2022 and 2021 are as follows:

Details about Accumulated Other Comprehensive Loss components	Affected line item in the Condensed Consolidated Statements of Operations	Three months ended
		March 31,
$ in millions		2022		2021
Net gains on cash flow hedges (Note 4):
	Interest expense	$	(0.2)	$	(0.2)
	Income tax expense	0.1		—
	Net of income taxes	(0.1)		(0.2)
Amortization of defined benefit pension items (Note 7):
	Other expense	0.3		0.6
	Income tax benefit	(0.1)		(0.1)
	Net of income taxes	0.2		0.5
Total reclassifications for the period, net of income taxes		$	0.1	$	0.3

Schedule of Supplemental Financial Information

Accounts receivable were as follows as of March 31, 2022 and December 31, 2021:

	March 31,		December 31,
$ in millions	2022		2021
Accounts receivable, net:
Customer receivables	$	47.4	$	42.3
Unbilled revenue	17.0		19.2
Amounts due from affiliates	3.7		3.1
Due from PJM transmission enhancement settlement	1.7		1.7
Other	4.3		5.5
Allowance for credit losses	(0.2)		(0.3)
Total accounts receivable, net	$	73.9	$	71.5

Accounts Receivable, Allowance for Credit Loss

The following table is a roll forward of our allowance for credit losses related to the accounts receivable balances for the three months ended March 31, 2022 and 2021:

$ in millions	Beginning Allowance Balance		Current Period Provision		Write-offs Charged Against Allowances		Recoveries Collected		Ending Allowance Balance
2022	$	0.3	$	(0.1)	$	(0.2)	$	0.2	$	0.2
2021	$	2.8	$	—	$	(0.7)	$	0.2	$	2.3

The allowance for credit losses primarily relates to utility customer receivables, including unbilled amounts. Expected credit loss estimates are developed by disaggregating customers into those with similar credit risk characteristics and using historical credit loss experience. In addition, we also consider how current and future economic conditions are expected to impact collectability, as applicable, including the economic impacts of the COVID-19 pandemic on our receivable balance as of March 31, 2022. Amounts are written off when reasonable collections efforts have been exhausted. During 2021, the current period provision and allowance for credit losses have decreased due to lower past due customer receivable balances.

New Accounting Pronouncements, Policy [Policy Text Block]

New Accounting Pronouncements Adopted in 2022 – We have assessed and determined that the new accounting pronouncements adopted did not have a material impact on our consolidated financial statements.

New Accounting Pronouncements Issued But Not Yet Effective – The following table provides a brief description of recent accounting pronouncements that could have a material impact on our consolidated financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or are expected to have no material impact on our consolidated financial statements.

ASU Number and Name	Description	Date of Adoption	Effect on the financial statements upon adoption
2020-04 and 2021-01, Reference Rate Form (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting	The amendments in these updates provide optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions that reference to LIBOR or another reference rate expected to be discontinued by reference rate reform, and clarify that certain optional expedients and exceptions in Topic 848 for contract modifications and hedge accounting apply to derivatives that are affected by the discounting transition. These amendments are effective for a limited period of time (March 12, 2020 - December 31, 2022). Implementation - We have established a process to measure and mitigate risks associated with the cessation of LIBOR. As part of this initiative, alternative benchmark rates have been, and continue to be, assessed, and implemented for newly executed agreements. Many of our existing agreements include provisions designed to facilitate an orderly transition from LIBOR. To the extent that the terms of the credit agreements do not align following the cessation of LIBOR rates, we will seek to negotiate contract amendments with counterparties or additional derivatives contracts.	Effective for all entities as of March 12, 2020 through December 31, 2022	We are implementing the reference rate reform and do not expect these amendments to have a material impact on our consolidated financial statements. See Implementation for further details.

Schedule of Cash and Cash Equivalents [Table Text Block]

The following table provides a summary of cash, cash equivalents, and restricted cash amounts reported on the Condensed Consolidated Balance Sheets that reconcile to the total of such amounts as shown on the Condensed Consolidated Statements of Cash Flows:

$ in millions	March 31, 2022		December 31, 2021
Cash and cash equivalents	$	32.1	$	26.6
Restricted cash (included in Prepayments and other current assets)	0.1		0.1
Cash, Cash Equivalents, and Restricted Cash, End of Period	$	32.2	$	26.7

Schedule of New Accounting Pronouncements

New Accounting Pronouncements Issued But Not Yet Effective – The following table provides a brief description of recent accounting pronouncements that could have a material impact on our consolidated financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or are expected to have no material impact on our consolidated financial statements.

ASU Number and Name	Description	Date of Adoption	Effect on the financial statements upon adoption
2020-04 and 2021-01, Reference Rate Form (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting	The amendments in these updates provide optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions that reference to LIBOR or another reference rate expected to be discontinued by reference rate reform, and clarify that certain optional expedients and exceptions in Topic 848 for contract modifications and hedge accounting apply to derivatives that are affected by the discounting transition. These amendments are effective for a limited period of time (March 12, 2020 - December 31, 2022). Implementation - We have established a process to measure and mitigate risks associated with the cessation of LIBOR. As part of this initiative, alternative benchmark rates have been, and continue to be, assessed, and implemented for newly executed agreements. Many of our existing agreements include provisions designed to facilitate an orderly transition from LIBOR. To the extent that the terms of the credit agreements do not align following the cessation of LIBOR rates, we will seek to negotiate contract amendments with counterparties or additional derivatives contracts.	Effective for all entities as of March 12, 2020 through December 31, 2022	We are implementing the reference rate reform and do not expect these amendments to have a material impact on our consolidated financial statements. See Implementation for further details.

Subsidiaries [Member]

Related Party Transaction [Line Items]

Schedule of Accumulated Other Comprehensive Income (Loss)

The changes in the components of Accumulated other comprehensive loss during the three months ended March 31, 2022 are as follows:

$ in millions	Change in Accumulated other comprehensive loss
Balance as of January 1, 2022	$	(31.8)
Amounts reclassified from AOCL to earnings	0.7
Net current period other comprehensive income	0.7
Balance as of March 31, 2022	$	(31.1)

Reclassification out of Accumulated Other Comprehensive Income

The amounts reclassified out of Accumulated other comprehensive loss by component during the three months ended March 31, 2022 and 2021 are as follows:

Details about Accumulated Other Comprehensive Loss components	Affected line item in the Condensed Consolidated Statements of Operations	Three months ended
		March 31,
$ in millions		2022		2021
Amortization of defined benefit pension items (Note 6):
	Other expense	0.9		1.3
	Income tax benefit	(0.2)		(0.3)
	Net of income taxes	0.7		1.0
Total reclassifications for the period, net of income taxes		$	0.7	$	1.0

Schedule of Supplemental Financial Information

Accounts receivable were as follows as of March 31, 2022 and December 31, 2021:

	March 31,		December 31,
$ in millions	2022		2021
Accounts receivable, net:
Customer receivables	46.5		$	41.6
Unbilled revenue	17.0		19.2
Amounts due from affiliates	4.3		4.4
Due from PJM transmission enhancement settlement	1.7		1.7
Other	4.3		5.3
Allowance for credit losses	(0.2)		(0.3)
Total accounts receivable, net	$	73.6	$	71.9

Accounts Receivable, Allowance for Credit Loss

The following table is a roll forward of our allowance for credit losses related to the accounts receivable balances for the three months ended March 31, 2022 and 2021:

$ in millions	Beginning Allowance Balance		Current Period Provision		Write-offs Charged Against Allowances		Recoveries Collected		Ending Allowance Balance
2022	$	0.3	$	(0.1)	$	(0.2)	$	0.2	$	0.2
2021	$	2.8	$	—	$	(0.7)	$	0.2	$	2.3

The allowance for credit losses primarily relates to utility customer receivables, including unbilled amounts. Expected credit loss estimates are developed by disaggregating customers into those with similar credit risk characteristics and using historical credit loss experience. In addition, we also consider how current and future economic conditions are expected to impact collectability, as applicable, including the economic impacts of the COVID-19 pandemic on our receivable balance as of March 31, 2022. Amounts are written off when reasonable collections efforts have been exhausted. During 2021, the current period provision and allowance for credit losses have decreased due to lower past due customer receivable balances.

New Accounting Pronouncements, Policy [Policy Text Block]

New Accounting Pronouncements Adopted in 2022 – We have assessed and determined that the new accounting pronouncements adopted did not have a material impact on our financial statements.

Schedule of Cash and Cash Equivalents [Table Text Block]

The following table provides a summary of cash, cash equivalents, and restricted cash amounts reported on the Condensed Balance Sheets that reconcile to the total of such amounts as shown on the Condensed Statements of Cash Flows:

$ in millions	March 31, 2022		December 31, 2021
Cash and cash equivalents	$	17.9	$	14.4
Restricted cash (included in Prepayments and other current assets)	0.1		0.1
Cash, Cash Equivalents, and Restricted Cash, End of Period	$	18.0	$	14.5

Schedule of New Accounting Pronouncements

New Accounting Pronouncements Issued But Not Yet Effective – The following table provides a brief description of recent accounting pronouncements that could have a material impact on our financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or are expected to have no material impact on our financial statements.

ASU Number and Name	Description	Date of Adoption	Effect on the financial statements upon adoption
2020-04 and 2021-01, Reference Rate Form (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting	The amendments in these updates provide optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions that reference to LIBOR or another reference rate expected to be discontinued by reference rate reform, and clarify that certain optional expedients and exceptions in Topic 848 for contract modifications and hedge accounting apply to derivatives that are affected by the discounting transition. These amendments are effective for a limited period of time (March 12, 2020 - December 31, 2022). Implementation - We have established a process to measure and mitigate risks associated with the cessation of LIBOR. As part of this initiative, alternative benchmark rates have been, and continue to be, assessed, and implemented for newly executed agreements. Many of our existing agreements include provisions designed to facilitate an orderly transition from LIBOR. To the extent that the terms of the credit agreements do not align following the cessation of LIBOR rates, we will seek to negotiate contract amendments with counterparties or additional derivatives contracts.	Effective for all entities as of March 12, 2020 through December 31, 2022	We are implementing the reference rate reform and do not expect these amendments to have a material impact on our financial statements. See Implementation for further details.