Income Taxes (Tables)

3 Months Ended

Mar. 31, 2018

Income Tax Disclosure [Abstract]

ScheduleOfRemeasurementsOfDeferredIncomeTaxesDueToTaxReform [Table Text Block]

The one-time impacts recorded by the Registrants to remeasure their deferred income tax balances at the 21% corporate federal income tax rate as of December 31, 2017 are presented below:

	Exelon(b)		Generation		ComEd		PECO		BGE		PHI		Pepco		DPL		ACE
Net Decrease to Deferred Income Tax Liability Balances	$	8,624	$	1,895	$	2,819	$	1,407	$	1,120	$	1,944	$	968	$	540	$	456

	Exelon	Generation	ComEd	PECO(c)	BGE	PHI	Pepco	DPL	ACE
Net Regulatory Liability Recorded(a)	7,315	N/A	2,818	1,394	1,124	1,979	976	545	458

	Exelon(b)		Generation		ComEd		PECO		BGE			PHI			Pepco			DPL			ACE
Net Deferred Income Tax Benefit/(Expense) Recorded	$	1,309	$	1,895	$	1	$	13	$	(4	)	$	(35	)	$	(8	)	$	(5	)	$	(2	)

__________

(a) Reflects the net regulatory liabilities recorded on a pre-tax basis before taking into consideration the income tax benefits associated with the ultimate settlement with customers.

(b) Amounts do not sum across due to deferred tax adjustments recorded at the Exelon Corporation parent company, primarily related to certain employee compensation plans.

(c) Given the regulatory treatment of income tax benefits related to electric and gas distribution repairs, PECO remains in an overall net regulatory asset position as of December 31, 2017 after recording the impacts related to the TCJA. Refer to Note 3 - Regulatory Matters for additional information.

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

The effective income tax rate from continuing operations varies from the U.S. Federal statutory rate principally due to the following:

	Three Months Ended March 31, 2018
	Exelon	Generation	ComEd	PECO	BGE	PHI	Pepco	DPL	ACE
U.S. Federal statutory rate	21.0%	21.0%	21.0%	21.0%	21.0%	21.0%	21.0%	21.0%	21.0%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	4.1	2.4	8.2	(3.9)	6.3	4.6	1.7	6.3	6.6
Qualified nuclear decommissioning trust fund income	(0.4)	(1.3)	—	—	—	—	—	—	—
Amortization of investment tax credit, including deferred taxes on basis difference	(1.3)	(4.3)	(0.2)	(0.1)	(0.1)	(0.2)	(0.1)	(0.2)	(0.3)
Plant basis differences	(2.7)	—	0.1	(14.2)	(0.7)	(2.6)	(3.4)	(1.3)	(2.6)
Production tax credits and other credits	(2.8)	(9.5)	(0.1)	—	—	—	—	—	—
Noncontrolling interests	(0.7)	(2.5)	—	—	—	—	—	—	—
Excess deferred tax amortization	(6.0)	—	(7.5)	(4.8)	(8.6)	(10.6)	(12.8)	(7.9)	(8.7)
Other	(2.8)	(1.3)	0.3	0.2	—	—	(0.3)	0.5	(3.5)
Effective income tax rate	8.4%	4.5%	21.8%	(1.8)%	17.9%	12.2%	6.1%	18.4%	12.5%

	Three Months Ended March 31, 2017(a)
	Exelon	Generation	ComEd	PECO	BGE	PHI	Pepco	DPL	ACE
U.S. Federal statutory rate	35.0%	35.0%	35.0%	35.0%	35.0%	35.0%	35.0%	35.0%	35.0%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	0.9	1.0	4.9	0.1	5.2	4.9	4.6	5.3	5.6
Qualified nuclear decommissioning trust fund income	3.5	7.8	—	—	—	—	—	—	—
Amortization of investment tax credit, including deferred taxes on basis difference	(0.4)	(0.7)	(0.2)	(0.1)	(0.1)	(0.2)	(0.1)	(0.3)	(0.4)
Plant basis differences	(2.4)	—	(0.2)	(13.2)	(0.9)	(3.8)	(5.8)	(1.9)	(3.4)
Production tax credits and other credits	(0.7)	(1.5)	—	—	—	—	—	—	—
Noncontrolling interest	—	0.1	—	—	—	—	—	—	—
Merger expenses(b)	(11.5)	(3.4)	—	—	—	(42.4)	(34.2)	(21.9)	(167.1)
Fitzpatrick bargain purchase gain	(6.6)	(14.8)	—	—	—	—	—	—	—
Other	(0.1)	(0.4)	—	0.3	(0.2)	(0.4)	0.5	—	(3.0)
Effective income tax rate	17.7%	23.1%	39.5%	22.1%	39.0%	(6.9)%	0.0%	16.2%	(133.3)%

_________

(a) Exelon retrospectively adopted the new standard Revenue from Contracts with Customers. The standard was adopted as of January 1, 2018. The effective income tax rates are recast to reflect the impact of the new standard.

(b) Includes a remeasurement of uncertain state income tax positions for Pepco and DPL.

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

The Registrants have the following unrecognized tax benefits as of March 31, 2018 and December 31, 2017:

	Exelon		Generation		ComEd		PECO		BGE		PHI		Pepco		DPL		ACE
March 31, 2018	$	733	$	464	$	2	$	—	$	120	$	125	$	59	$	21	$	14

	Exelon		Generation		ComEd		PECO		BGE		PHI		Pepco		DPL		ACE
December 31, 2017	$	743	$	468	$	2	$	—	$	120	$	125	$	59	$	21	$	14