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Amount of current income tax expense (benefit) pertaining to taxable income (loss) from continuing operations.

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Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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The amount deducted from an entities' taxes, reflecting a percentage of an amount invested in certain assets spread over the useful life of those assets; includes deferred investment tax credits.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Income Taxes - Components of Income Tax Expense (Benefit) from Continuing Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended	12 Months Ended
	Dec. 31, 2018	Mar. 23, 2016	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Income taxes	$ 26			$ 120	$ (126)	$ 753
Exelon Generation Co L L C [Member]
Income Taxes [Line Items]
Income taxes				(108)	(1,376)	282
Commonwealth Edison Co [Member]
Income Taxes [Line Items]
Income taxes				168	417	301
PECO Energy Co [Member]
Income Taxes [Line Items]
Income taxes				6	104	149
Baltimore Gas and Electric Company [Member]
Income Taxes [Line Items]
Income taxes				74	218	174
Potomac Electric Power Company [Member]
Income Taxes [Line Items]
Income taxes				13	105	41
Delmarva Power & Light Company [Member]
Income Taxes [Line Items]
Income taxes				22	71	22
Atlantic City Electric Company [Member]
Income Taxes [Line Items]
Income taxes				12	26	(4)
Pepco Holdings LLC [Member]
Income Taxes [Line Items]
Income taxes				35	217
Pepco Holdings LLC [Member] \| Successor [Member]
Income Taxes [Line Items]
Income taxes			$ 3
Pepco Holdings LLC [Member] \| Predecessor [Member]
Income Taxes [Line Items]
Income taxes		$ 17
Internal Revenue Service (IRS) [Member]
Income Taxes [Line Items]
Current				226	194	60
Deferred				(98)	(471)	600
Investment Tax Credit				(24)	(25)	(24)
Internal Revenue Service (IRS) [Member] \| Exelon Generation Co L L C [Member]
Income Taxes [Line Items]
Current				337	584	513
Deferred				(347)	(2,005)	(254)
Investment Tax Credit				(21)	(21)	(20)
Internal Revenue Service (IRS) [Member] \| Commonwealth Edison Co [Member]
Income Taxes [Line Items]
Current				(63)	(191)	(135)
Deferred				145	523	379
Investment Tax Credit				(2)	(2)	(2)
Internal Revenue Service (IRS) [Member] \| PECO Energy Co [Member]
Income Taxes [Line Items]
Current				11	71	63
Deferred				10	28	72
Investment Tax Credit				0	0	0
Internal Revenue Service (IRS) [Member] \| Baltimore Gas and Electric Company [Member]
Income Taxes [Line Items]
Current				(5)	74	51
Deferred				47	101	88
Investment Tax Credit				0	(1)	(1)
Internal Revenue Service (IRS) [Member] \| Potomac Electric Power Company [Member]
Income Taxes [Line Items]
Current				28	(20)	(118)
Deferred				(21)	114	136
Investment Tax Credit				0	0	0
Internal Revenue Service (IRS) [Member] \| Delmarva Power & Light Company [Member]
Income Taxes [Line Items]
Current				(3)	(24)	(88)
Deferred				13	82	97
Investment Tax Credit				0	0	0
Internal Revenue Service (IRS) [Member] \| Atlantic City Electric Company [Member]
Income Taxes [Line Items]
Current				(14)	(12)	(26)
Deferred				18	34	22
Investment Tax Credit				0	0	0
Internal Revenue Service (IRS) [Member] \| Pepco Holdings LLC [Member]
Income Taxes [Line Items]
Current				(4)	(60)
Deferred				24	250
Investment Tax Credit				(1)	(1)
Internal Revenue Service (IRS) [Member] \| Pepco Holdings LLC [Member] \| Successor [Member]
Income Taxes [Line Items]
Current			(281)
Deferred			283
Investment Tax Credit			(1)
Internal Revenue Service (IRS) [Member] \| Pepco Holdings LLC [Member] \| Predecessor [Member]
Income Taxes [Line Items]
Current		0
Deferred		10
Investment Tax Credit		0
State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Current				(1)	14	39
Deferred				17	162	78
State and Local Jurisdiction [Member] \| Exelon Generation Co L L C [Member]
Income Taxes [Line Items]
Current				6	65	45
Deferred				(83)	1	(2)
State and Local Jurisdiction [Member] \| Commonwealth Edison Co [Member]
Income Taxes [Line Items]
Current				(29)	(49)	(4)
Deferred				117	136	63
State and Local Jurisdiction [Member] \| PECO Energy Co [Member]
Income Taxes [Line Items]
Current				1	14	9
Deferred				(16)	(9)	5
State and Local Jurisdiction [Member] \| Baltimore Gas and Electric Company [Member]
Income Taxes [Line Items]
Current				0	(5)	5
Deferred				32	49	31
State and Local Jurisdiction [Member] \| Potomac Electric Power Company [Member]
Income Taxes [Line Items]
Current				0	(2)	7
Deferred				6	13	16
State and Local Jurisdiction [Member] \| Delmarva Power & Light Company [Member]
Income Taxes [Line Items]
Current				0	0	1
Deferred				12	13	12
State and Local Jurisdiction [Member] \| Atlantic City Electric Company [Member]
Income Taxes [Line Items]
Current				0	0	0
Deferred				8	4	$ 0
State and Local Jurisdiction [Member] \| Pepco Holdings LLC [Member]
Income Taxes [Line Items]
Current				7	(4)
Deferred				$ 9	$ 32
State and Local Jurisdiction [Member] \| Pepco Holdings LLC [Member] \| Successor [Member]
Income Taxes [Line Items]
Current			(11)
Deferred			$ 13
State and Local Jurisdiction [Member] \| Pepco Holdings LLC [Member] \| Predecessor [Member]
Income Taxes [Line Items]
Current		0
Deferred		$ 7