Regulatory Matters Regulatory Matters - Schedule of Regulatory Liabilities (Details) - USD ($) $ in Millions		Jun. 30, 2016	Dec. 31, 2015
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		$ 503	$ 369
Noncurrent		4,389	4,201
Regulatory Liabilities		4,892	4,570
Regulatory Assets		11,680	6,824
Electric Transmission And Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		84	95
Other Postretirement Benefits [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		90	94
Nuclear Decommissioning [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		2,642	2,577
Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		1,648	1,527
Deferred Lease Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		42
Energy Efficiency Demand Response Programs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		134	92
Dlc Program Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		9	9
Gas Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		24	28
Over Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		164	131
Over Recovered Decoupling Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		3	1
Regulatory Liabilities Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		52	16
Baltimore Gas and Electric Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		60	38
Noncurrent		137	184
Regulatory Liabilities		197	222
Regulatory Assets		781	781
Baltimore Gas and Electric Company [Member] | Over Recovered Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			14
Baltimore Gas and Electric Company [Member] | Electric Transmission And Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Baltimore Gas and Electric Company [Member] | Abandonment costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		1	1
Baltimore Gas and Electric Company [Member] | Over Recovered Decoupling Gas Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		3	1
Baltimore Gas and Electric Company [Member] | Over Recovered Decoupling Electric Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		26
Baltimore Gas and Electric Company [Member] | Other Postretirement Benefits [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Baltimore Gas and Electric Company [Member] | Nuclear Decommissioning [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Baltimore Gas and Electric Company [Member] | Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		172	195
Baltimore Gas and Electric Company [Member] | Energy Efficiency Demand Response Programs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Baltimore Gas and Electric Company [Member] | Dlc Program Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Baltimore Gas and Electric Company [Member] | Gas Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Baltimore Gas and Electric Company [Member] | Over Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[1]	8	18
Baltimore Gas and Electric Company [Member] | Over Recovered Decoupling Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[2]	3	1
Baltimore Gas and Electric Company [Member] | Regulatory Liabilities Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		14	8
Baltimore Gas and Electric Company [Member] | Over-Recovered Natural Gas Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		8	5
PECO Energy Co [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		128	112
Noncurrent		529	527
Regulatory Liabilities		657	639
Regulatory Assets		1,684	1,617
PECO Energy Co [Member] | Over Recovered NonBypassable Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		7
PECO Energy Co [Member] | Over Recovered Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		2	3
PECO Energy Co [Member] | Electric Transmission And Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		84	95
PECO Energy Co [Member] | Other Postretirement Benefits [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
PECO Energy Co [Member] | Nuclear Decommissioning [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		437	405
PECO Energy Co [Member] | Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
PECO Energy Co [Member] | Energy Efficiency Demand Response Programs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		37	40
PECO Energy Co [Member] | Dlc Program Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		9	9
PECO Energy Co [Member] | Gas Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		24	28
PECO Energy Co [Member] | Over Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[3]	63	60
PECO Energy Co [Member] | Over Recovered Decoupling Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
PECO Energy Co [Member] | Regulatory Liabilities Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		3	2
PECO Energy Co [Member] | Over-Recovered Natural Gas Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		23	22
PECO Energy Co [Member] | Default Service Provider Program [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		31	35
Commonwealth Edison Co [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		153	155
Noncurrent		3,524	3,459
Regulatory Liabilities		3,677	3,614
Regulatory Assets		1,136	1,113
Commonwealth Edison Co [Member] | Over Recovered Energy Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		13
Commonwealth Edison Co [Member] | Electric Transmission And Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Commonwealth Edison Co [Member] | Other Postretirement Benefits [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Commonwealth Edison Co [Member] | Nuclear Decommissioning [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		2,205	2,172
Commonwealth Edison Co [Member] | Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		1,330	1,332
Commonwealth Edison Co [Member] | Energy Efficiency Demand Response Programs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		97	52
Commonwealth Edison Co [Member] | Dlc Program Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			0
Commonwealth Edison Co [Member] | Gas Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Commonwealth Edison Co [Member] | Over Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[4]	41	53
Commonwealth Edison Co [Member] | Over Recovered Decoupling Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Commonwealth Edison Co [Member] | Regulatory Liabilities Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		4	5
Commonwealth Edison Co [Member] | Renewable energy Requirements [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		28	24
Commonwealth Edison Co [Member] | Over Recovered Electric Supply Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			29
PEPCO Holdings Inc [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current			66
Noncurrent			147
Regulatory Liabilities			213
Regulatory Assets			2,582
PEPCO Holdings Inc [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		101
Noncurrent		171
Regulatory Liabilities		272
Regulatory Assets		3,774
PEPCO Holdings Inc [Member] | Electric Transmission And Distribution Tax Repairs [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			0
PEPCO Holdings Inc [Member] | Electric Transmission And Distribution Tax Repairs [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0
PEPCO Holdings Inc [Member] | Other Postretirement Benefits [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			0
PEPCO Holdings Inc [Member] | Other Postretirement Benefits [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0
PEPCO Holdings Inc [Member] | Nuclear Decommissioning [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			0
PEPCO Holdings Inc [Member] | Nuclear Decommissioning [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0
PEPCO Holdings Inc [Member] | Removal Costs [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			150
PEPCO Holdings Inc [Member] | Removal Costs [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		146
PEPCO Holdings Inc [Member] | Deferred Lease Revenue [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[5]	42
PEPCO Holdings Inc [Member] | Energy Efficiency Demand Response Programs [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			1
PEPCO Holdings Inc [Member] | Energy Efficiency Demand Response Programs [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0
PEPCO Holdings Inc [Member] | Dlc Program Cost [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			0
PEPCO Holdings Inc [Member] | Dlc Program Cost [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0
PEPCO Holdings Inc [Member] | Gas Distribution Tax Repairs [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			0
PEPCO Holdings Inc [Member] | Gas Distribution Tax Repairs [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0
PEPCO Holdings Inc [Member] | Over Recovered Energy And Transmission Costs [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			27
PEPCO Holdings Inc [Member] | Over Recovered Energy And Transmission Costs [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		52
PEPCO Holdings Inc [Member] | Over Recovered Decoupling Revenue [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			0
PEPCO Holdings Inc [Member] | Over Recovered Decoupling Revenue [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0
PEPCO Holdings Inc [Member] | Regulatory Liabilities Other [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			35
PEPCO Holdings Inc [Member] | Regulatory Liabilities Other [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		32
Potomac Electric Power Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		27	15
Noncurrent		24	29
Regulatory Liabilities		51	44
Regulatory Assets		798	801
Potomac Electric Power Company [Member] | Over Recovered Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		12	14
Potomac Electric Power Company [Member] | Electric Transmission And Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Potomac Electric Power Company [Member] | Other Postretirement Benefits [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Potomac Electric Power Company [Member] | Nuclear Decommissioning [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Potomac Electric Power Company [Member] | Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		20	21
Potomac Electric Power Company [Member] | Energy Efficiency Demand Response Programs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Potomac Electric Power Company [Member] | Dlc Program Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Potomac Electric Power Company [Member] | Gas Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Potomac Electric Power Company [Member] | Over Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[6]	22	16
Potomac Electric Power Company [Member] | Over Recovered Decoupling Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Potomac Electric Power Company [Member] | Regulatory Liabilities Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		9	7
Potomac Electric Power Company [Member] | Over Recovered Electric Supply Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		10	2
Delmarva Power and Light Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		53	49
Noncurrent		102	111
Regulatory Liabilities		155	160
Regulatory Assets		358	371
Delmarva Power and Light Company [Member] | Over Recovered Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		7	11
Delmarva Power and Light Company [Member] | Electric Transmission And Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Delmarva Power and Light Company [Member] | Other Postretirement Benefits [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Delmarva Power and Light Company [Member] | Nuclear Decommissioning [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Delmarva Power and Light Company [Member] | Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		126	129
Delmarva Power and Light Company [Member] | Energy Efficiency Demand Response Programs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Delmarva Power and Light Company [Member] | Dlc Program Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Delmarva Power and Light Company [Member] | Gas Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Delmarva Power and Light Company [Member] | Over Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[7]	21	19
Delmarva Power and Light Company [Member] | Over Recovered Decoupling Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Delmarva Power and Light Company [Member] | Regulatory Liabilities Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		8	12
Delmarva Power and Light Company [Member] | Over-Recovered Natural Gas Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		4	4
Delmarva Power and Light Company [Member] | Over Recovered Electric Supply Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		10	4
Atlantic City Electric Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		21	18
Noncurrent		2	7
Regulatory Liabilities		23	25
Regulatory Assets		515	512
Atlantic City Electric Company [Member] | Electric Transmission And Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Atlantic City Electric Company [Member] | Other Postretirement Benefits [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Atlantic City Electric Company [Member] | Nuclear Decommissioning [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Atlantic City Electric Company [Member] | Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Atlantic City Electric Company [Member] | Energy Efficiency Demand Response Programs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	1
Atlantic City Electric Company [Member] | Dlc Program Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Atlantic City Electric Company [Member] | Gas Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Atlantic City Electric Company [Member] | Over Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[8]	9	8
Atlantic City Electric Company [Member] | Over Recovered Decoupling Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Atlantic City Electric Company [Member] | Regulatory Liabilities Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		14	16
Under Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets		103	84
Under Recovered Energy And Transmission Costs [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets	[1]	36	40
Under Recovered Energy And Transmission Costs [Member] | PECO Energy Co [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets		0	1	[3]
Under Recovered Energy And Transmission Costs [Member] | Commonwealth Edison Co [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets	[4]	41	43
Under Recovered Energy And Transmission Costs [Member] | PEPCO Holdings Inc [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets			33
Under Recovered Energy And Transmission Costs [Member] | PEPCO Holdings Inc [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets		26
Under Recovered Energy And Transmission Costs [Member] | Potomac Electric Power Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets		0	9	[6]
Under Recovered Energy And Transmission Costs [Member] | Delmarva Power and Light Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets	[7]	6	11
Under Recovered Energy And Transmission Costs [Member] | Atlantic City Electric Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets	[8]	$ 20	$ 13

[1] As of June 30, 2016, BGE's regulatory asset of $36 million included $6 million of costs associated with transmission costs recoverable through its FERC approved formula rate, $29 million related to under-recovered electric energy costs, and $1 million of abandonment costs to be recovered upon FERC approval. As of June 30, 2016, BGE's regulatory liability of $8 million related to $8 million of over-recovered natural gas costs. As of December 31, 2015, BGE’s regulatory asset of $40 million included $12 million of costs associated with transmission costs recoverable through its FERC approved formula rate and $28 million related to under-recovered electric energy costs. As of December 31, 2015, BGE’s regulatory liability of $18 million related to $14 million of over-recovered transmission costs and $5 million of over-recovered natural gas costs, offset by $1 million of abandonment costs to be recovered upon FERC approval.

[2] Represents the electric and natural gas distribution costs recoverable from customers under BGE’s decoupling mechanism. As of June 30, 2016, BGE had a regulatory asset of $26 million related to under-recovered electric revenue decoupling and a regulatory liability of $3 million related to over-recovered natural gas revenue decoupling. As of December 31, 2015, BGE had a regulatory asset of $30 million related to under-recovered electric revenue decoupling and a regulatory liability of $1 million related to over-recovered natural gas revenue decoupling.

[3] As of June 30, 2016, PECO's regulatory liability of $63 million included $31 million related to over-recovered costs under the DSP program, $23 million related to the over-recovered natural gas costs under the PGC, $7 million related to over-recovered non-bypassable transmission service charges and$2 million related to over-recovered electric transmission costs. As of December 31, 2015, PECO's regulatory asset of $1 million related to under-recovered non-bypassable transmission service charges. As of December 31, 2015, PECO's regulatory liability of $60 million included $35 million related to over-recovered costs under the DSP program, $22 million related to the over-recovered natural gas costs under the PGC and $3 million related to the over-recovered electric transmission costs.

[4] As of June 30, 2016, ComEd’s regulatory asset of $41 million included $4 million related to under-recovered energy costs, $30 million associated with transmission costs recoverable through its FERC approved formula rate, and $7 million of Constellation merger and integration costs to be recovered upon FERC approval. As of June 30, 2016, ComEd’s regulatory liability of $41 million included $13 million related to over-recovered energy costs and $28 million associated with revenues received for renewable energy requirements. As of December 31, 2015, ComEd’s regulatory asset of $43 million included $5 million related to under-recovered energy costs, $31 million associated with transmission costs recoverable through its FERC approved formula rate, and $7 million of Constellation merger and integration costs to be recovered upon FERC approval. As of December 31, 2015, ComEd’s regulatory liability of $53 million included $29 million related to over-recovered energy costs and $24 million associated with revenues received for renewable energy requirements.

[5] Represents the regulatory liability recorded at Exelon and PHI for deferred rent related to a lease that is recoverable through the ratemaking process at Pepco, DPL and ACE.

[6] As of June 30, 2016, Pepco's regulatory liability of $22 million included $12 million of over-recovered transmission costs and $10 million of over-recovered electric energy costs. As of December 31, 2015, Pepco's regulatory asset of $9 million included $5 million of transmission costs recoverable through its FERC approved formula rate and $4 million of recoverable abandonment costs. As of December 31, 2015, Pepco's regulatory liability of $16 million included $14 million of over-recovered transmission costs and $2 million of over-recovered electric energy costs.

[7] As of June 30, 2016, DPL's regulatory asset of $6 million related to under-recovered electric energy costs. As of June 30, 2016, DPL's regulatory liability of $21 million included $4 million related to over-recovered natural gas costs under the GCR mechanism, $10 million of over-recovered electric energy costs, and $7 million of over-recovered transmission costs. As of December 31, 2015, DPL's regulatory asset of $11 million included $7 million of transmission costs recoverable through its FERC approved formula rate, $3 million of recoverable abandonment costs, and $1 million of under-recovered electric energy costs. As of December 31, 2015, DPL's regulatory liability of $19 million included $4 million related to the over-recovered natural gas costs under the GCR mechanism, $4 million of over-recovered electric energy costs, and $11 million of over-recovered transmission costs.

[8] As of June 30, 2016, ACE's regulatory asset of $20 million related to of under-recovered electric energy costs. As of June 30, 2016, ACE's regulatory liability of $9 million related to over-recovered transmission costs. As of December 31, 2015, ACE's regulatory asset of $13 million included $2 million of transmission costs recoverable through its FERC approved formula rate and $11 million of under-recovered electric energy costs. As of December 31, 2015, ACE's regulatory liability of $8 million related to over-recovered transmission costs.