Nuclear Decommissioning (Tables) - Exelon Generation Co L L C [Member]

9 Months Ended

Sep. 30, 2016

Schedule Of Nuclear Decommissioning [Line Items]

Nuclear decommissioning asset retirement obligation rollforward

The following table provides a rollforward of the nuclear decommissioning ARO reflected on Exelon’s and Generation’s Consolidated Balance Sheets from December 31, 2015 to September 30, 2016: 

Nuclear decommissioning ARO at December 31, 2015(a)	$	8,246
Accretion expense	325
Net increase due to changes in, and timing of, estimated cash flows	444
Costs incurred to decommission retired plants	(6		)
Nuclear decommissioning ARO at September 30, 2016(a)	$	9,009

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(a) Includes $44 million and $7 million for the current portion of the ARO at September 30, 2016 and December 31, 2015, respectively, which is included in Other current liabilities on Exelon’s and Generation’s Consolidated Balance Sheets.

Unrealized Gains (Losses) on nuclear decommissioning trust funds

The following table provides unrealized gains on NDT funds for the three and nine months ended September 30, 2016 and 2015:

	Exelon and Generation					Exelon and Generation
	Three Months Ended September 30,					Nine Months Ended   September 30,
	2016		2015			2016		2015
Net unrealized gains (losses) on decommissioning trust      funds — Regulatory Agreement Units(a)	$	155	$	(301	)	$	286	$	(385	)
Net unrealized gains (losses) on decommissioning trust      funds — Non-Regulatory Agreement Units(b)(c)	116		(218		)	216		(274		)

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(a) Net unrealized gains related to Generation’s NDT funds associated with Regulatory Agreement Units are included in Regulatory liabilities on Exelon’s Consolidated Balance Sheets and Noncurrent payables to affiliates on Generation’s Consolidated Balance Sheets.

(b) Excludes $(5) million of net unrealized gain related to the Zion Station pledged assets for the three months ended September 30, 2016. Excludes $(2) million and $9 million of net unrealized gain related to the Zion Station pledged assets for the nine months ended September 30, 2016 and 2015, respectively. Net unrealized gains related to Zion Station pledged assets are included in the Payable for Zion Station decommissioning on Exelon’s and Generation’s Consolidated Balance Sheets.

(c) Net unrealized gains related to Generation’s NDT funds with Non-Regulatory Agreement Units are included within Other, net in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income.

Zion Station pledged assets

September 30, 2016 and December 31, 2015:

	Exelon and Generation
	September 30, 2016		December 31, 2015
Carrying value of Zion Station pledged assets	$	135	$	206
Payable to Zion Solutions(a)	124		189
Current portion of payable to Zion Solutions(b)	91		99
Cumulative withdrawals by Zion Solutions to pay decommissioning costs(c)	855		786

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(a) Excludes a liability recorded within Exelon’s and Generation’s Consolidated Balance Sheets related to the tax obligation on the unrealized activity associated with the Zion Station NDT funds. The NDT funds will be utilized to satisfy the tax obligations as gains and losses are realized.

(b) Included in Other current liabilities within Exelon’s and Generation’s Consolidated Balance Sheets.

(c) Includes project expenses to decommission Zion Station and estimated tax payments on Zion Station NDT fund earnings.