Regulatory Matters - Schedule of Regulatory Assets (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended	12 Months Ended
		Mar. 23, 2016	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2016	Mar. 31, 2015	Dec. 31, 2008
Regulated Operations [Abstract]
Regulatory Liability, Current			$ 602	$ 602	$ 369
Regulatory Assets [Line Items]
Current regulatory assets			1,342	1,342	759
Noncurrent regulatory assets			10,046	10,046	6,065
Regulatory Assets			11,388	11,388	6,824
Business Combination, Integration Related Costs	[1],[2]			143	87
AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets			477	477	0
UnderFundedStatusDefinedBenefitPostretirement [Member]
Regulatory Assets [Line Items]
Regulatory Assets			1,087	1,087
Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets			4,162	4,162	3,156
Deferred Income Taxes [Member]
Regulatory Assets [Line Items]
Regulatory Assets			2,016	2,016	1,616
AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets			701	701	399
Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			188	188	189
Debt Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			124	124	47
Fair Value Of Long Term Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets			812	812	162
Fair Value Of Supply Contract [Member]
Regulatory Assets [Line Items]
Regulatory Assets			1,085	1,085
Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets			5	5	9
Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Regulatory Assets			111	111	108
Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			305	305	286
Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets			56	56	52
Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets			260	260	247
Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			89	89	84
Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			36	36	2
Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets			10	10	20
Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets			7	7	87
Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			621	$ 621	279
Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period				5 years
Regulatory Assets			25	$ 25	6
Conservation Voltage Reductio [Member]
Regulatory Assets [Line Items]
Regulatory Assets					3
Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Regulatory Assets			27	27	30
Other Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets			49	49	29
CAP Arrearage [Member]
Regulatory Assets [Line Items]
Regulatory Assets			11	11	7
Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			8	8	0
Workers Compensation and Long-Term Disability [Member]
Regulatory Assets [Line Items]
Regulatory Assets			34	34	0
Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets			31	31	6
Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			138	138	0
PECO Energy Co [Member]
Regulated Operations [Abstract]
Regulatory Liability, Current			127	127	112
Regulatory Assets [Line Items]
Current regulatory assets			29	29	34
Noncurrent regulatory assets			1,681	1,681	1,583
Regulatory Assets			1,710	1,710	1,617
Business Combination, Integration Related Costs	[2]			5	4
PECO Energy Co [Member] | AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
PECO Energy Co [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
PECO Energy Co [Member] | Deferred Income Taxes [Member]
Regulatory Assets [Line Items]
Regulatory Assets			1,583	$ 1,583	1,473
PECO Energy Co [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period				10 years
Regulatory Assets			49	$ 49	63
PECO Energy Co [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
PECO Energy Co [Member] | Debt Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			1	1	1
PECO Energy Co [Member] | Fair Value Of Long Term Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
PECO Energy Co [Member] | Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
PECO Energy Co [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Regulatory Assets			23	23	22
PECO Energy Co [Member] | Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			26	26	30
PECO Energy Co [Member] | Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
PECO Energy Co [Member] | Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
PECO Energy Co [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	1
PECO Energy Co [Member] | Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
PECO Energy Co [Member] | Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
PECO Energy Co [Member] | Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
PECO Energy Co [Member] | Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			1	1	1
PECO Energy Co [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
PECO Energy Co [Member] | Conservation Voltage Reductio [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
PECO Energy Co [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
PECO Energy Co [Member] | Other Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets			9	9	13
PECO Energy Co [Member] | CAP Arrearage [Member]
Regulatory Assets [Line Items]
Regulatory Assets			11	11	7
PECO Energy Co [Member] | Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
PECO Energy Co [Member] | Workers Compensation and Long-Term Disability [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
PECO Energy Co [Member] | Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets			7	7	6
PECO Energy Co [Member] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Baltimore Gas and Electric Company [Member]
Regulated Operations [Abstract]
Regulatory Liability, Current			50	50	38
Regulatory Assets [Line Items]
Current regulatory assets			208	208	267
Noncurrent regulatory assets			504	504	514
Regulatory Assets			712	712	781
Business Combination, Integration Related Costs	[2],[3]			(1)	5
Baltimore Gas and Electric Company [Member] | AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
Baltimore Gas and Electric Company [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets			4	4	12
Baltimore Gas and Electric Company [Member] | UnderRecoveredElectricEnergyCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets			28	28	28
Baltimore Gas and Electric Company [Member] | Legacy AMI [Member]
Regulatory Assets [Line Items]
Regulatory Assets			54	54
Baltimore Gas and Electric Company [Member] | Recoverable Smart Meter Related Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			32	32
Baltimore Gas and Electric Company [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Baltimore Gas and Electric Company [Member] | Deferred Income Taxes [Member]
Regulatory Assets [Line Items]
Regulatory Assets			98	98	79
Baltimore Gas and Electric Company [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets			230	230
Regulatory Assets			230	230	196
Baltimore Gas and Electric Company [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Baltimore Gas and Electric Company [Member] | Debt Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			7	7	8
Baltimore Gas and Electric Company [Member] | Fair Value Of Long Term Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Baltimore Gas and Electric Company [Member] | Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets			5	5	9
Baltimore Gas and Electric Company [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Regulatory Assets			12	12	19
Baltimore Gas and Electric Company [Member] | Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			1	1	1
Baltimore Gas and Electric Company [Member] | Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Baltimore Gas and Electric Company [Member] | Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Baltimore Gas and Electric Company [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			38	38	40
Baltimore Gas and Electric Company [Member] | Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			1	1	2
Baltimore Gas and Electric Company [Member] | Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets			10	10	20
Baltimore Gas and Electric Company [Member] | Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets			7	7	87
Baltimore Gas and Electric Company [Member] | Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			285	285	278
Baltimore Gas and Electric Company [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			10	10	6	$ 6	$ 4
Baltimore Gas and Electric Company [Member] | Conservation Voltage Reductio [Member]
Regulatory Assets [Line Items]
Regulatory Assets					3
Baltimore Gas and Electric Company [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Regulatory Assets			3	3	30
Baltimore Gas and Electric Company [Member] | Other Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets			5	5	3
Baltimore Gas and Electric Company [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Business Combination, Integration Related Costs				6
Baltimore Gas and Electric Company [Member] | CAP Arrearage [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
Baltimore Gas and Electric Company [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets			38	38	16
Baltimore Gas and Electric Company [Member] | Advanced Metering Infrastructure Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			144	144
Baltimore Gas and Electric Company [Member] | Over-Recovered Natural Gas Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			3	3
Baltimore Gas and Electric Company [Member] | Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Baltimore Gas and Electric Company [Member] | Workers Compensation and Long-Term Disability [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Baltimore Gas and Electric Company [Member] | Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Baltimore Gas and Electric Company [Member] | Abandonment costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			3	3
Baltimore Gas and Electric Company [Member] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Pepco Holdings LLC [Member]
Regulatory Assets [Line Items]
Business Combination, Integration Related Costs	[2],[3]			28	3
Pepco Holdings LLC [Member] | Predecessor [Member]
Regulated Operations [Abstract]
Regulatory Liability, Current					66
Regulatory Assets [Line Items]
Current regulatory assets					305
Noncurrent regulatory assets					2,277
Regulatory Assets					2,582
Business Combination, Integration Related Costs	[3]	$ 29		19
Pepco Holdings LLC [Member] | Successor [Member]
Regulated Operations [Abstract]
Regulatory Liability, Current			79	79
Regulatory Assets [Line Items]
Current regulatory assets			653	653
Noncurrent regulatory assets			2,851	2,851
Regulatory Assets			3,504	3,504
Business Combination, Integration Related Costs	[3]		69
Pepco Holdings LLC [Member] | AssetRemovalCosts [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					369
Pepco Holdings LLC [Member] | AssetRemovalCosts [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			477	477
Pepco Holdings LLC [Member] | Other Postretirement Benefits [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					910
Pepco Holdings LLC [Member] | Other Postretirement Benefits [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0
Pepco Holdings LLC [Member] | Deferred Income Taxes [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					214
Pepco Holdings LLC [Member] | Deferred Income Taxes [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			260	260
Pepco Holdings LLC [Member] | AMI Expenses [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					267
Pepco Holdings LLC [Member] | AMI Expenses [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			258	258
Pepco Holdings LLC [Member] | Under Recovered Distribution Service Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
Pepco Holdings LLC [Member] | Under Recovered Distribution Service Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0
Pepco Holdings LLC [Member] | Debt Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			81	81
Pepco Holdings LLC [Member] | Debt Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					36
Pepco Holdings LLC [Member] | Fair Value Of Long Term Debt [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
Pepco Holdings LLC [Member] | Fair Value Of Long Term Debt [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			671	671
Pepco Holdings LLC [Member] | Fair Value Of Supply Contract [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			1,085	1,085
Pepco Holdings LLC [Member] | Severance [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
Pepco Holdings LLC [Member] | Severance [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0
Pepco Holdings LLC [Member] | Asset Retirement Obligations [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					1
Pepco Holdings LLC [Member] | Asset Retirement Obligations [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0
Pepco Holdings LLC [Member] | Environmental Restoration Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
Pepco Holdings LLC [Member] | Environmental Restoration Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0
Pepco Holdings LLC [Member] | Under Recovered Uncollectible Accounts Expense [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
Pepco Holdings LLC [Member] | Under Recovered Uncollectible Accounts Expense [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0
Pepco Holdings LLC [Member] | Renewable Energy And Associated REC [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					6
Pepco Holdings LLC [Member] | Renewable Energy And Associated REC [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			2	2
Pepco Holdings LLC [Member] | Under Recovered Energy And Transmission Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					33
Pepco Holdings LLC [Member] | Under Recovered Energy And Transmission Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			28	28
Pepco Holdings LLC [Member] | Deferred Storm Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					43
Pepco Holdings LLC [Member] | Deferred Storm Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			35	35
Pepco Holdings LLC [Member] | Electric Generation Related Regulatory Asset [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
Pepco Holdings LLC [Member] | Electric Generation Related Regulatory Asset [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0
Pepco Holdings LLC [Member] | Rate Stabilization Deferral [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
Pepco Holdings LLC [Member] | Rate Stabilization Deferral [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0
Pepco Holdings LLC [Member] | Energy Efficiency And Demand Response Programs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					401
Pepco Holdings LLC [Member] | Energy Efficiency And Demand Response Programs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			335	335
Pepco Holdings LLC [Member] | Merger Integration Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
Pepco Holdings LLC [Member] | Merger Integration Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			15	15
Pepco Holdings LLC [Member] | Conservation Voltage Reductio [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
Pepco Holdings LLC [Member] | Under Recovered Decoupling Revenue [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					14
Pepco Holdings LLC [Member] | Under Recovered Decoupling Revenue [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			24	24
Pepco Holdings LLC [Member] | Other Assets [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					32
Pepco Holdings LLC [Member] | Other Assets [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			29	29
Pepco Holdings LLC [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Business Combination, Integration Related Costs				16
Pepco Holdings LLC [Member] | CAP Arrearage [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0
Pepco Holdings LLC [Member] | Deferred Project Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
Pepco Holdings LLC [Member] | Deferred Project Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			8	8
Pepco Holdings LLC [Member] | Workers Compensation and Long-Term Disability [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					31
Pepco Holdings LLC [Member] | Workers Compensation and Long-Term Disability [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			34	34
Pepco Holdings LLC [Member] | Recoverable Vacation Pay [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					23
Pepco Holdings LLC [Member] | Recoverable Vacation Pay [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			24	24
Pepco Holdings LLC [Member] | Stranded Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets					202
Pepco Holdings LLC [Member] | Stranded Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets			138	138
Potomac Electric Power Company [Member]
Regulated Operations [Abstract]
Regulatory Liability, Current			11	11	15
Regulatory Assets [Line Items]
Current regulatory assets			162	162	140
Noncurrent regulatory assets			690	690	661
Regulatory Assets			852	852	801
Potomac Electric Power Company [Member] | AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets			134	134	92
Potomac Electric Power Company [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets					5
Potomac Electric Power Company [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Potomac Electric Power Company [Member] | Deferred Income Taxes [Member]
Regulatory Assets [Line Items]
Regulatory Assets			171	171	137
Potomac Electric Power Company [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets			174	174	180
Potomac Electric Power Company [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Potomac Electric Power Company [Member] | Debt Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			17	17	19
Potomac Electric Power Company [Member] | Fair Value Of Long Term Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Potomac Electric Power Company [Member] | Fair Value Of Supply Contract [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0
Potomac Electric Power Company [Member] | Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Potomac Electric Power Company [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	1
Potomac Electric Power Company [Member] | Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Potomac Electric Power Company [Member] | Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Potomac Electric Power Company [Member] | Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Potomac Electric Power Company [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			6	6	9
Potomac Electric Power Company [Member] | Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			12	12	19
Potomac Electric Power Company [Member] | Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Potomac Electric Power Company [Member] | Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Potomac Electric Power Company [Member] | Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			250	250	289
Potomac Electric Power Company [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			11	11	0
Potomac Electric Power Company [Member] | Conservation Voltage Reductio [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
Potomac Electric Power Company [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Regulatory Assets			21	21	10
Potomac Electric Power Company [Member] | Other Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets			22	22	14
Potomac Electric Power Company [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Business Combination, Integration Related Costs				11
Potomac Electric Power Company [Member] | CAP Arrearage [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0
Potomac Electric Power Company [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets			31	31	26
Potomac Electric Power Company [Member] | Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Potomac Electric Power Company [Member] | Workers Compensation and Long-Term Disability [Member]
Regulatory Assets [Line Items]
Regulatory Assets			34	34	31
Potomac Electric Power Company [Member] | Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Potomac Electric Power Company [Member] | Abandonment costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets					4
Potomac Electric Power Company [Member] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Delmarva Power and Light Company [Member]
Regulated Operations [Abstract]
Regulatory Liability, Current			43	43	49
Regulatory Assets [Line Items]
Current regulatory assets			59	59	72
Noncurrent regulatory assets			289	289	299
Regulatory Assets			348	348	371
Business Combination, Integration Related Costs	[2]			20	2
Delmarva Power and Light Company [Member] | AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets			88	88	69
Delmarva Power and Light Company [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets			1	1	7
Delmarva Power and Light Company [Member] | UnderRecoveredElectricEnergyCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets			4	4	1
Delmarva Power and Light Company [Member] | Legacy AMI [Member]
Regulatory Assets [Line Items]
Regulatory Assets			14	14
Delmarva Power and Light Company [Member] | Recoverable Smart Meter Related Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			41	41
Delmarva Power and Light Company [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Delmarva Power and Light Company [Member] | Deferred Income Taxes [Member]
Regulatory Assets [Line Items]
Regulatory Assets			38	38	36
Delmarva Power and Light Company [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets			84	84	87
Delmarva Power and Light Company [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Delmarva Power and Light Company [Member] | Debt Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			9	9	10
Delmarva Power and Light Company [Member] | Fair Value Of Long Term Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Delmarva Power and Light Company [Member] | Fair Value Of Supply Contract [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0
Delmarva Power and Light Company [Member] | Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Delmarva Power and Light Company [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Delmarva Power and Light Company [Member] | Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Delmarva Power and Light Company [Member] | Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Delmarva Power and Light Company [Member] | Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	1
Delmarva Power and Light Company [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			5	5	11
Delmarva Power and Light Company [Member] | Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			5	5	6
Delmarva Power and Light Company [Member] | Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Delmarva Power and Light Company [Member] | Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Delmarva Power and Light Company [Member] | Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			85	85	111
Delmarva Power and Light Company [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			4	4	0
Delmarva Power and Light Company [Member] | Conservation Voltage Reductio [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
Delmarva Power and Light Company [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Regulatory Assets			3	3	4
Delmarva Power and Light Company [Member] | Other Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets			5	5	9
Delmarva Power and Light Company [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Business Combination, Integration Related Costs				4
Delmarva Power and Light Company [Member] | CAP Arrearage [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0
Delmarva Power and Light Company [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets			20	20	18
Delmarva Power and Light Company [Member] | Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			8	8	13			$ 41
Delmarva Power and Light Company [Member] | Workers Compensation and Long-Term Disability [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Delmarva Power and Light Company [Member] | Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets			14	14	14
Delmarva Power and Light Company [Member] | Abandonment costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets					3
Delmarva Power and Light Company [Member] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Atlantic City Electric Company [Member]
Regulated Operations [Abstract]
Regulatory Liability, Current			25	25	18
Regulatory Assets [Line Items]
Current regulatory assets			96	96	98
Noncurrent regulatory assets			405	405	414
Regulatory Assets			501	501	512
Business Combination, Integration Related Costs	[2]			19	1
Atlantic City Electric Company [Member] | AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets			255	255	208
Atlantic City Electric Company [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets			6	6	2
Atlantic City Electric Company [Member] | UnderRecoveredElectricEnergyCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets			11	11	11
Atlantic City Electric Company [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Atlantic City Electric Company [Member] | Deferred Income Taxes [Member]
Regulatory Assets [Line Items]
Regulatory Assets			51	51	41
Atlantic City Electric Company [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Atlantic City Electric Company [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Atlantic City Electric Company [Member] | Debt Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			6	6	7
Atlantic City Electric Company [Member] | Fair Value Of Long Term Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Atlantic City Electric Company [Member] | Fair Value Of Supply Contract [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0
Atlantic City Electric Company [Member] | Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Atlantic City Electric Company [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Atlantic City Electric Company [Member] | Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Atlantic City Electric Company [Member] | Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Atlantic City Electric Company [Member] | Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets			2	2	5
Atlantic City Electric Company [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			17	17	13
Atlantic City Electric Company [Member] | Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			18	18	18
Atlantic City Electric Company [Member] | Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Atlantic City Electric Company [Member] | Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Atlantic City Electric Company [Member] | Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	1
Atlantic City Electric Company [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Atlantic City Electric Company [Member] | Conservation Voltage Reductio [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
Atlantic City Electric Company [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Atlantic City Electric Company [Member] | Other Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets			4	4	8
Atlantic City Electric Company [Member] | CAP Arrearage [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0
Atlantic City Electric Company [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets			19	19	15
Atlantic City Electric Company [Member] | Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Atlantic City Electric Company [Member] | Workers Compensation and Long-Term Disability [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Atlantic City Electric Company [Member] | Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets			10	10	9
Atlantic City Electric Company [Member] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			138	138	202
Commonwealth Edison Co [Member]
Regulated Operations [Abstract]
Regulatory Liability, Current			329	329	155
Regulatory Assets [Line Items]
Current regulatory assets			190	190	218
Noncurrent regulatory assets			977	977	895
Regulatory Assets			1,167	1,167	1,113
Business Combination, Integration Related Costs	[2],[3]			(6)	9
Commonwealth Edison Co [Member] | AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Commonwealth Edison Co [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Commonwealth Edison Co [Member] | Deferred Income Taxes [Member]
Regulatory Assets [Line Items]
Regulatory Assets			75	75	64
Commonwealth Edison Co [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets			164	164	140
Commonwealth Edison Co [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			188	188	189
Business Combination, Integration Related Costs				11	11
Commonwealth Edison Co [Member] | Debt Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			42	42	46
Commonwealth Edison Co [Member] | Fair Value Of Long Term Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Commonwealth Edison Co [Member] | Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Commonwealth Edison Co [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Regulatory Assets			76	76	67
Commonwealth Edison Co [Member] | Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			278	278	255
Commonwealth Edison Co [Member] | Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets			56	56	52
Commonwealth Edison Co [Member] | Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets			258	258	247
Commonwealth Edison Co [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			23	23	43
Business Combination, Integration Related Costs				8	7
Commonwealth Edison Co [Member] | Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Commonwealth Edison Co [Member] | Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Commonwealth Edison Co [Member] | Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Commonwealth Edison Co [Member] | Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Commonwealth Edison Co [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Commonwealth Edison Co [Member] | Conservation Voltage Reductio [Member]
Regulatory Assets [Line Items]
Regulatory Assets					0
Commonwealth Edison Co [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Commonwealth Edison Co [Member] | Other Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets			7	7	10
Commonwealth Edison Co [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Business Combination, Integration Related Costs				8
Commonwealth Edison Co [Member] | CAP Arrearage [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Commonwealth Edison Co [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets			22	22	15
Commonwealth Edison Co [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			20	20	36
Commonwealth Edison Co [Member] | Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Commonwealth Edison Co [Member] | Workers Compensation and Long-Term Disability [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Commonwealth Edison Co [Member] | Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Commonwealth Edison Co [Member] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			0	0	0
Commonwealth Edison Co [Member] | Recoverable Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets			54	54	47
Over Recovered Energy And Transmission Costs [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Assets [Line Items]
Regulatory Assets			9	9	19
Over Recovered Transmission Costs [Member] | Potomac Electric Power Company [Member]
Regulated Operations [Abstract]
Regulatory Liability, Current			5	5	14
Over Recovered Transmission Costs [Member] | Delmarva Power and Light Company [Member]
Regulated Operations [Abstract]
Regulatory Liability, Current			3	3	11
Over Recovered Transmission Costs [Member] | Atlantic City Electric Company [Member]
Regulated Operations [Abstract]
Regulatory Liability, Current			4	4
Over Recovered Electric Supply Cost [Member] | Potomac Electric Power Company [Member]
Regulated Operations [Abstract]
Regulatory Liability, Current			3	3	2
Over Recovered Electric Supply Cost [Member] | Delmarva Power and Light Company [Member]
Regulated Operations [Abstract]
Regulatory Liability, Current			2	2	4
Over Recovered Electric Supply Cost [Member] | Atlantic City Electric Company [Member]
Regulated Operations [Abstract]
Regulatory Liability, Current			1	1
Over Recovered Electric Supply Cost [Member] | Commonwealth Edison Co [Member]
Regulated Operations [Abstract]
Regulatory Liability, Current			$ 30	$ 30	29
Over-Recovered Natural Gas Costs [Member] | Delmarva Power and Light Company [Member]
Regulated Operations [Abstract]
Regulatory Liability, Current					$ 4

[1] Reflects costs (benefits) recorded at Exelon related to financing, including mark-to-market activity on forward-starting interest rate swaps.

[2] The costs incurred are classified primarily within Operating and maintenance expense in the Registrants’ respective Consolidated Statements of Operations and Comprehensive Income, with the exception of the financing costs, which are included within Interest expense. Costs do not include merger commitments discussed above.

[3] , includes the reversal of previously incurred acquisition, integration and financing costs of $8 million, $6 million, $11 million, $4 million, and $16 million incurred at ComEd, BGE, Pepco, DPL and PHI, respectively, that have been deferred and recorded as a regulatory asset for anticipated recovery. See Note 3 - Regulatory Matters for more information.