Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2020

Asset Retirement Obligation Disclosure [Abstract]

Asset Retirement Obligation Rollforward

The following table provides a rollforward of the nuclear decommissioning ARO reflected in Exelon’s and Generation’s Consolidated Balance Sheets, from January 1, 2019 to December 31, 2020:

Nuclear decommissioning ARO at January 1, 2019	$	10,005
Net increase due to changes in, and timing of, estimated future cash flows	864
Sale of Oyster Creek	(755)
Accretion expense	479
Costs incurred related to decommissioning plants	(89)
Nuclear decommissioning ARO at December 31, 2019(a)	10,504
Net increase due to changes in, and timing of, estimated future cash flows	1,022
Accretion Expense	489
Costs incurred related to decommissioning plants	(93)
Nuclear decommissioning ARO at December 31, 2020(a)	$	11,922

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(a)Includes $80 million and $112 million as the current portion of the ARO at December 31, 2020 and 2019, respectively, which is included in Other current liabilities in Exelon’s and Generation’s Consolidated Balance Sheets.

The following table provides a rollforward of the non-nuclear AROs reflected in the Registrants’ Consolidated Balance Sheets from January 1, 2019 to December 31, 2020:

	Exelon		Generation		ComEd		PECO		BGE		PHI		Pepco		DPL		ACE
Non-nuclear AROs at January 1, 2019	$	471	$	238	$	121	$	28	$	25	$	52	$	37	$	11	$	4
Net increase (decrease) due to changes in, and timing of, estimated future cash flows	17		7		8		—		(2)		4		3		1		—
Development projects	2		2		—		—		—		—		—		—		—
Accretion expense(a)	16		12		1		1		1		1		1		—		—
Asset divestitures	(42)		(42)		—		—		—		—		—		—		—
Payments	(4)		(1)		(1)		(1)		(1)		—		—		—		—
Non-nuclear AROs at December 31, 2019	460		216		129		28		23		57		41		12		4
Net increase (decrease) due to changes in, and timing of, estimated future cash flows	7		2		—		2		1		1		(3)		2		2
Development projects	1		1		—		—		—		—		—		—		—
Accretion expense(a)	16		11		1		1		1		1		1		—		—
Asset divestitures	(4)		(4)		—		—		—		—		—		—		—
Payments	(9)		(4)		(1)		(2)		(2)		—		—		—		—
AROs reclassified to liabilities held for sale(b)	(10)		(10)		—		—		—		—		—		—		—
Non-nuclear AROs at December 31, 2020	$	461	$	212	$	129	$	29	$	23	$	59	$	39	$	14	$	6

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(a)For ComEd, PECO, BGE, PHI, Pepco, and DPL, the majority of the accretion is recorded as an increase to a regulatory asset due to the associated regulatory treatment.

(b)Represents AROs related to Generation's solar business, which were classified as held for sale as a result of the sale agreement. See Note 2 — Mergers, Acquisitions, and Dispositions for additional information.