Early Plant Retirements (Tables)

3 Months Ended

Mar. 31, 2019

Property, Plant and Equipment [Abstract]

Schedule of Other Operating Cost and Expense, by Component [Table Text Block]

	Three Months Ended March 31,
Income statement expense (pre-tax)	2019			2018
Depreciation and amortization(a)
Accelerated depreciation(b)	$	74		$	137
Accelerated nuclear fuel amortization	5			15
Operating and maintenance(c)	(83		)	26
Total	$	(4	)	$	178

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(a) Reflects incremental accelerated depreciation and amortization for TMI for the three months ended March 31, 2019. Reflects incremental accelerated depreciation for TMI and Oyster Creek for the three months ended March 31, 2018. The Oyster Creek amounts are from February 2, 2018 through March 31, 2018.

(b) Reflects incremental accelerated depreciation of plant assets, including any ARC.

(c) In 2019, primarily reflects decrease to estimated decommissioning costs for TMI. See Note 13 — Nuclear Decommissioning for additional information on the first quarter 2019 TMI ARO update. In 2018, primarily reflects materials and supplies inventory reserve adjustments, employee related costs and CWIP impairments.

Implications of Potential Early Plant Retirement on Balance Sheet [Table Text Block]

The following table provides the balance sheet amounts as of March 31, 2019 for Exelon's and Generation’s significant assets and liabilities associated with the Mystic Units 8 and 9 and Everett Marine Terminal assets that would potentially be impacted by a decision to permanently cease generation operations in the absence of long-term market rule changes.

	March 31, 2019
Asset Balances
Materials and supplies inventory	$	30
Fuel inventory	22
Completed plant, net	900
Construction work in progress	2
Liability Balances
Asset retirement obligation	(1		)