Regulatory Matters Regulatory Matters - Schedule of Regulatory Assets (Details) - USD ($) $ in Millions		3 Months Ended			6 Months Ended			12 Months Ended
		Jun. 30, 2016		Jun. 30, 2015	Jun. 30, 2016		Jun. 30, 2015	Dec. 31, 2015
Regulatory Assets [Line Items]
Current		$ 1,559			$ 1,559			$ 759
Noncurrent		10,121			10,121			6,065
Regulatory Assets		11,680			11,680			6,824
Regulatory Liabilities		4,892			4,892			4,570
Business Combination, Integration Related Costs		1		$ (87)	103		$ 21
Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets		4,160	[1]		4,160	[1]		3,156
Deferred Income Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1,928			1,928			1,616
AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets		712			712			399
Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		207			207			189
Loss on Reacquired Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		130			130			47
Fair Value Of Long Term Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		847			847			162	[2]
Fair Value Of Supply Contract [Member]
Regulatory Assets [Line Items]
Current		1,350			1,350
Employee Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets		7			7			9
Asset Retirement Obligation Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		117			117			108
Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		290			290			286
Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets		54			54			52
Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets		226			226			247
Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		103			103			84
Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		43			43			2
Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets		15			15			20
Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets		54			54			87
Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		634			634			279
Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		23			23			6
ConservativeVoltageReductionProgram [Member]
Regulatory Assets [Line Items]
Regulatory Assets								3
Regulatory Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets		44			44			29
Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Current		40			40
Regulatory Assets								30
Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		10			10			0
Workers Compensation and Long-Term Disability [Member]
Regulatory Assets [Line Items]
Regulatory Assets		31			31			0
Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets		47			47			6
Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		169			169			0
CAP Arrearage [Member]
Regulatory Assets [Line Items]
Regulatory Assets		7			7			7
AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		425			425
Under funded Benefit Post Retirement Obligation [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1,087			1,087
Alternative Energy Credits [Member]
Regulatory Assets [Line Items]
Regulatory Assets		7			7
Commonwealth Edison Co [Member]
Regulatory Assets [Line Items]
Current		213			213			218
Noncurrent		923			923			895
Regulatory Assets		1,136			1,136			1,113
Regulatory Liabilities		3,677			3,677			3,614
Business Combination, Integration Related Costs		1		3	(7)		6
Commonwealth Edison Co [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets		19			19			15
Commonwealth Edison Co [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets		30			30
Commonwealth Edison Co [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Commonwealth Edison Co [Member] | Deferred Income Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory Assets		70	[3]		70	[3]		64
Commonwealth Edison Co [Member] | Recoverable Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		44			44			47
Commonwealth Edison Co [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets								140
Commonwealth Edison Co [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[4]	207			207			189
Business Combination, Integration Related Costs					11			11
Commonwealth Edison Co [Member] | Loss on Reacquired Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		44			44			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] | Employee Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Commonwealth Edison Co [Member] | Asset Retirement Obligation Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		74			74			67
Commonwealth Edison Co [Member] | Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		262			262			255
Commonwealth Edison Co [Member] | Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets		54			54			52
Commonwealth Edison Co [Member] | Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets		221			221			247
Commonwealth Edison Co [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[5]	41			41			43
Business Combination, Integration Related Costs					7			7
Commonwealth Edison Co [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		28			28			36
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
Commonwealth Edison Co [Member] | ConservativeVoltageReductionProgram [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
Commonwealth Edison Co [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets		7			7			10
Business Combination, Integration Related Costs					8
Commonwealth Edison Co [Member] | Advanced Metering Infrastructure Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		5			5
Commonwealth Edison Co [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
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] | Annual Reconciliations [Member]
Regulatory Assets [Line Items]
Regulatory Assets		163			163			142
Commonwealth Edison Co [Member] | Under-Recovered Electric Supply Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		4			4			5
Commonwealth Edison Co [Member] | ElectricTransmissionCostsUnderRecovery [Member]
Regulatory Assets [Line Items]
Regulatory Assets								31
Commonwealth Edison Co [Member] | Recoverable Smart Meter Related Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		156			156
PECO Energy Co [Member]
Regulatory Assets [Line Items]
Current		48			48			34
Noncurrent		1,636			1,636			1,583
Regulatory Assets		1,684			1,684			1,617
Regulatory Liabilities		657			657			639
Business Combination, Integration Related Costs		1		1	2		2
PECO Energy Co [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
PECO Energy Co [Member] | Deferred Income Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1,536			1,536			1,473
PECO Energy Co [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets								63
PECO Energy Co [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
PECO Energy Co [Member] | Loss on Reacquired Debt [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] | Fair Value Of Supply Contract [Member]
Regulatory Assets [Line Items]
Current		0			0
PECO Energy Co [Member] | Employee Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
PECO Energy Co [Member] | Asset Retirement Obligation Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		22			22			22
PECO Energy Co [Member] | Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		27			27			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	[6]
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
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] | ConservativeVoltageReductionProgram [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PECO Energy Co [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets		13			13			13
PECO Energy Co [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
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		21			21			6
PECO Energy Co [Member] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
PECO Energy Co [Member] | CAP Arrearage [Member]
Regulatory Assets [Line Items]
Regulatory Assets		7			7			7
PECO Energy Co [Member] | Recoverable Smart Meter Related Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		56			56
Baltimore Gas and Electric Company [Member]
Regulatory Assets [Line Items]
Current		261			261			267
Noncurrent		520			520			514
Regulatory Assets		781			781			781
Regulatory Liabilities		197			197			222
Business Combination, Integration Related Costs		(5)		1	(4)		3
Baltimore Gas and Electric Company [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets		30			30			16
Baltimore Gas and Electric Company [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets		6			6			12
Baltimore Gas and Electric Company [Member] | UnderRecoveredElectricEnergyCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		29			29			28
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 Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory Assets		94	[3]		94	[3]		79
Baltimore Gas and Electric Company [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Noncurrent		240			240			196
Regulatory Assets	[7]							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] | Loss on Reacquired Debt [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] | Employee Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets		7			7			9
Baltimore Gas and Electric Company [Member] | Asset Retirement Obligation Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		20			20			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	[8]	36			36			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		15			15			20
Baltimore Gas and Electric Company [Member] | Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets		54			54			87
Baltimore Gas and Electric Company [Member] | Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		264			264			278
Baltimore Gas and Electric Company [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[9]	11			11			6
Baltimore Gas and Electric Company [Member] | Merger Integration Costs [Member] | Pepco Holdings [Member]
Regulatory Assets [Line Items]
Regulatory Assets		6			6
Baltimore Gas and Electric Company [Member] | ConservativeVoltageReductionProgram [Member]
Regulatory Assets [Line Items]
Regulatory Assets								3
Baltimore Gas and Electric Company [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets		5			5			3
Business Combination, Integration Related Costs					6
Baltimore Gas and Electric Company [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Current	[10]	26			26
Regulatory Assets	[10]							30
Baltimore Gas and Electric Company [Member] | Under-Recovered Electric Revenue Decoupling [Member]
Regulatory Assets [Line Items]
Regulatory Assets								30
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] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Baltimore Gas and Electric Company [Member] | Recoverable Smart Meter Related Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		240			240
Baltimore Gas and Electric Company [Member] | Legacy AMI [Member]
Regulatory Assets [Line Items]
Regulatory Assets		56			56
Baltimore Gas and Electric Company [Member] | AMI Post Test Year [Member]
Regulatory Assets [Line Items]
Regulatory Assets		32			32
PEPCO Holdings Inc [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Current								305
Noncurrent								2,277
Regulatory Assets								2,582
Regulatory Liabilities								213
PEPCO Holdings Inc [Member] | Successor [Member]
Regulatory Assets [Line Items]
Current		730			730
Noncurrent		3,044			3,044
Regulatory Assets		3,774			3,774
Regulatory Liabilities		272			272
PEPCO Holdings Inc [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets								5
PEPCO Holdings Inc [Member] | Other Postretirement Benefits [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								910
PEPCO Holdings Inc [Member] | Other Postretirement Benefits [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[1]	0			0
PEPCO Holdings Inc [Member] | Deferred Income Tax Charge [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								214
PEPCO Holdings Inc [Member] | Deferred Income Tax Charge [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		228			228
PEPCO Holdings Inc [Member] | AMI Expenses [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								267
PEPCO Holdings Inc [Member] | AMI Expenses [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		260			260
PEPCO Holdings Inc [Member] | Under Recovered Distribution Service Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Under Recovered Distribution Service Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
PEPCO Holdings Inc [Member] | Loss on Reacquired Debt [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								36
PEPCO Holdings Inc [Member] | Loss on Reacquired Debt [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[11]	85			85
PEPCO Holdings Inc [Member] | Fair Value Of Long Term Debt [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Fair Value Of Long Term Debt [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[2]	698			698
PEPCO Holdings Inc [Member] | Fair Value Of Supply Contract [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[12]	1,350			1,350
PEPCO Holdings Inc [Member] | Employee Severance [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Employee Severance [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
PEPCO Holdings Inc [Member] | Asset Retirement Obligation Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								1
PEPCO Holdings Inc [Member] | Asset Retirement Obligation Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1			1
PEPCO Holdings Inc [Member] | Environmental Restoration Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Environmental Restoration Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
PEPCO Holdings Inc [Member] | Under Recovered Uncollectible Accounts Expense [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Under Recovered Uncollectible Accounts Expense [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
PEPCO Holdings Inc [Member] | Renewable Energy And Associated REC [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								6
PEPCO Holdings Inc [Member] | Renewable Energy And Associated REC [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		5			5
PEPCO Holdings Inc [Member] | Under Recovered Energy And Transmission Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								33
PEPCO Holdings Inc [Member] | Under Recovered Energy And Transmission Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		26			26
PEPCO Holdings Inc [Member] | Deferred Storm Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								43
PEPCO Holdings Inc [Member] | Deferred Storm Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		42			42
PEPCO Holdings Inc [Member] | Electric Generation Related Regulatory Asset [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Electric Generation Related Regulatory Asset [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
PEPCO Holdings Inc [Member] | Rate Stabilization Deferral [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Rate Stabilization Deferral [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
PEPCO Holdings Inc [Member] | Energy Efficiency And Demand Response Programs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								401
PEPCO Holdings Inc [Member] | Energy Efficiency And Demand Response Programs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		369			369
PEPCO Holdings Inc [Member] | Merger Integration Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Merger Integration Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		12			12
PEPCO Holdings Inc [Member] | ConservativeVoltageReductionProgram [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Regulatory Assets [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								32
PEPCO Holdings Inc [Member] | Regulatory Assets [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		16			16
PEPCO Holdings Inc [Member] | Under Recovered Decoupling Revenue [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								14
PEPCO Holdings Inc [Member] | Under Recovered Decoupling Revenue [Member] | Successor [Member]
Regulatory Assets [Line Items]
Current		14			14
PEPCO Holdings Inc [Member] | Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		10			10
PEPCO Holdings Inc [Member] | Deferred Project Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Workers Compensation and Long-Term Disability [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								31
PEPCO Holdings Inc [Member] | Workers Compensation and Long-Term Disability [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		31			31
PEPCO Holdings Inc [Member] | Recoverable Vacation Pay [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								23
PEPCO Holdings Inc [Member] | Recoverable Vacation Pay [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		26			26
PEPCO Holdings Inc [Member] | Abandonment costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets								4
PEPCO Holdings Inc [Member] | Stranded Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								202
PEPCO Holdings Inc [Member] | Stranded Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		169			169
PEPCO Holdings Inc [Member] | AssetRemovalCosts [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								369
PEPCO Holdings Inc [Member] | AssetRemovalCosts [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		425			425
PEPCO Holdings Inc [Member] | Alternative Energy Credits [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[13]	7			7
Potomac Electric Power Company [Member]
Regulatory Assets [Line Items]
Current		129			129			140
Noncurrent		669			669			661
Regulatory Assets		798			798			801
Regulatory Liabilities		51			51			44
Potomac Electric Power Company [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets		38			38			36
Potomac Electric Power Company [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0	[1]		0	[1]		0
Potomac Electric Power Company [Member] | Deferred Income Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory Assets		148	[3]		148	[3]		137
Potomac Electric Power Company [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets		174	[7]		174	[7]		180
Potomac Electric Power Company [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
Potomac Electric Power Company [Member] | Loss on Reacquired Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		18			18			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] | Employee Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Potomac Electric Power Company [Member] | Asset Retirement Obligation Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1			1			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		0			0			9	[14]
Potomac Electric Power Company [Member] | Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		17			17			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		266			266			289
Potomac Electric Power Company [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		9	[15]		9	[15]		0
Potomac Electric Power Company [Member] | ConservativeVoltageReductionProgram [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
Potomac Electric Power Company [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets		10			10			14
Business Combination, Integration Related Costs					9
Potomac Electric Power Company [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Current		12			12
Regulatory Assets								10
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		31			31			31
Potomac Electric Power Company [Member] | Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Potomac Electric Power Company [Member] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Potomac Electric Power Company [Member] | AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		112			112			92
Potomac Electric Power Company [Member] | Recoverable Smart Meter Related Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		139			139
Potomac Electric Power Company [Member] | Legacy AMI [Member]
Regulatory Assets [Line Items]
Regulatory Assets		78			78
Potomac Electric Power Company [Member] | AMI Post Test Year [Member]
Regulatory Assets [Line Items]
Regulatory Assets		2			2
Delmarva Power and Light Company [Member]
Regulatory Assets [Line Items]
Current		63			63			72
Noncurrent		295			295			299
Regulatory Assets		358			358			371
Regulatory Liabilities		155			155			160
Business Combination, Integration Related Costs		0		1	16		1
Delmarva Power and Light Company [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets		19			19			18
Delmarva Power and Light Company [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets								7
Delmarva Power and Light Company [Member] | UnderRecoveredElectricEnergyCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets								1
Delmarva Power and Light Company [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0	[1]		0	[1]		0
Delmarva Power and Light Company [Member] | Deferred Income Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory Assets		36	[3]		36	[3]		36
Delmarva Power and Light Company [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets		86	[7]		86	[7]		87
Delmarva Power and Light Company [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
Delmarva Power and Light Company [Member] | Loss on Reacquired Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		10			10			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] | Employee Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Delmarva Power and Light Company [Member] | Asset Retirement Obligation Costs [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		1			1			1
Delmarva Power and Light Company [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[16]	6			6			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		103			103			111
Delmarva Power and Light Company [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		3	[17]		3	[17]		0
Delmarva Power and Light Company [Member] | ConservativeVoltageReductionProgram [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
Delmarva Power and Light Company [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets		3			3			9
Business Combination, Integration Related Costs					3
Delmarva Power and Light Company [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Current		2			2
Regulatory Assets								4
Delmarva Power and Light Company [Member] | Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		10			10			13
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		15			15			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
Delmarva Power and Light Company [Member] | AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		78			78			69
Delmarva Power and Light Company [Member] | Recoverable Smart Meter Related Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		43			43
Delmarva Power and Light Company [Member] | Legacy AMI [Member]
Regulatory Assets [Line Items]
Regulatory Assets		14			14
Atlantic City Electric Company [Member]
Regulatory Assets [Line Items]
Current		97			97			98
Noncurrent		418			418			414
Regulatory Assets		515			515			512
Regulatory Liabilities		23			23			25
Business Combination, Integration Related Costs		2		$ 1	15		$ 1
Atlantic City Electric Company [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets		17			17			15
Atlantic City Electric Company [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets								2
Atlantic City Electric Company [Member] | UnderRecoveredElectricEnergyCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		20			20			11
Atlantic City Electric Company [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0	[1]		0	[1]		0
Atlantic City Electric Company [Member] | Deferred Income Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory Assets		44	[3]		44	[3]		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
Atlantic City Electric Company [Member] | Loss on Reacquired Debt [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] | Employee Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Atlantic City Electric Company [Member] | Asset Retirement Obligation Costs [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		4			4			5
Atlantic City Electric Company [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[18]	20			20			13
Atlantic City Electric Company [Member] | Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		20			20			18
Atlantic City Electric Company [Member] | Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets		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] | ConservativeVoltageReductionProgram [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
Atlantic City Electric Company [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets		5			5			8
Atlantic City Electric Company [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
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		11			11			9
Atlantic City Electric Company [Member] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		169			169			202
Atlantic City Electric Company [Member] | AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		236			236			208
Renewable energy Requirements [Member] | Commonwealth Edison Co [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		28			28			24
Over Recovered Transmission Costs [Member] | PECO Energy Co [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		2			2			3
Over Recovered Transmission Costs [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities								14
Over Recovered Transmission Costs [Member] | Potomac Electric Power Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		12			12			14
Over Recovered Transmission Costs [Member] | Delmarva Power and Light Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		7			7			11
Over Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		164			164			131
Over Recovered Energy And Transmission Costs [Member] | Commonwealth Edison Co [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities	[5]	41			41			53
Over Recovered Energy And Transmission Costs [Member] | PECO Energy Co [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities	[6]	63			63			60
Over Recovered Energy And Transmission Costs [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities	[8]	8			8			18
Over Recovered Energy And Transmission Costs [Member] | PEPCO Holdings Inc [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities								27
Over Recovered Energy And Transmission Costs [Member] | PEPCO Holdings Inc [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		52			52
Over Recovered Energy And Transmission Costs [Member] | Potomac Electric Power Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities	[14]	22			22			16
Over Recovered Energy And Transmission Costs [Member] | Delmarva Power and Light Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities	[16]	21			21			19
Over Recovered Energy And Transmission Costs [Member] | Atlantic City Electric Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities	[18]	9			9			8
Over Recovered Electric Supply Cost [Member] | Commonwealth Edison Co [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities								29
Over Recovered Electric Supply Cost [Member] | Potomac Electric Power Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		10			10			2
Over Recovered Electric Supply Cost [Member] | Delmarva Power and Light Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		10			10			4
Over-Recovered Natural Gas Costs [Member] | PECO Energy Co [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		23			23			22
Over-Recovered Natural Gas Costs [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		8			8			5
Over-Recovered Natural Gas Costs [Member] | Delmarva Power and Light Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		$ 4			$ 4			$ 4

[1] As of June 30, 2016, the pension and other postretirement benefits regulatory asset at Exelon includes regulatory assets of $1,087 million established at the date of the PHI Merger related to unrecognized costs that are probable of regulatory recovery. The regulatory assets are amortized over periods from 3 to 15 years, depending on the underlying component. Pepco, DPL and ACE are currently recovering these costs through base rates. Pepco, DPL and ACE are not earning a return on the recovery of these costs in base rates.

[2] ncludes the unamortized regulatory assets recorded for the difference between carrying value and fair value of long-term debt of BGE as of the Constellation merger date and at Exelon and PHI for the difference between carrying value and fair value of long-term debt of Pepco, DPL and ACE as of the PHI Merger date.

[3] As of June 30, 2016, includes transmission-related regulatory assets that require FERC approval separate from the transmission formula rate of $19 million, $30 million, $38 million, $19 million and $17 million for ComEd, BGE, Pepco, DPL and ACE, respectively. As of December 31, 2015, includes transmission-related regulatory assets that require FERC approval separate from the transmission formula rate of $15 million, $16 million, $36 million, $18 million and $15 million for ComEd, BGE, Pepco, DPL and ACE, respectively.

[4] As of June 30, 2016, ComEd’s regulatory asset of $207 million was comprised of $163 million for the 2014 - 2016 annual reconciliations and $44 million related to significant one-time events including $28 million of deferred storm costs, $11 million of Constellation and PHI merger and integration related costs and $5 million of smart meter related costs. As of December 31, 2015, ComEd’s regulatory asset of $189 million was comprised of $142 million for the 2014 and 2015 annual reconciliations and $47 million related to significant one-time events, including $36 million of deferred storm costs and $11 million of Constellation merger and integration related costs. See Note 4— Merger, Acquisitions, and Dispositions of the Exelon 2015 Form 10-K for further information.

[5] 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.

[6] 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.

[7] $139 million for Pepco and $43 million for DPL, of which $78 million for Pepco and $14 million for DPL relates to retired legacy meters which are not earning a return

[8] 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.

[9] As of June 30, 2016, BGE's regulatory asset of $11 million included $6 million of previously incurred PHI acquisition costs as authorized by the June 2016 rate case order.

[10] 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.

[11] Includes at Exelon and PHI the regulatory asset recorded at PHI for debt costs that are recoverable through the ratemaking process at Pepco, DPL, and ACE which were eliminated at Exelon and PHI as part of acquisition accounting.

[12] Represents the regulatory asset recorded at Exelon and PHI offsetting the fair value adjustments related to Pepco's, DPL's and ACE's electricity and natural gas energy supply contracts recorded at PHI as of the PHI Merger date. Pepco, DPL and ACE are allowed full recovery of the costs of these contracts through their respective rate making processes.

[13] 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.

[14] 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.

[15] epresents previously incurred PHI acquisition costs expected to be recovered in distribution rates

[16] 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.

[17] .

[18] 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.