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

3 Months Ended

Mar. 31, 2015

Exelon Generation Co L L C [Member]

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, 2014 to March 31, 2015:

Nuclear decommissioning ARO at December 31, 2014(a)	$	6,961
Net increase due to changes in, and timing of, estimated future cash flows(b)	55
Accretion expense	94
Nuclear decommissioning ARO at March 31, 2015(a)	$	7,110

(a) Includes $8 million as the current portion of the ARO at March 31, 2015 and December 31, 2014, which is included in Other current liabilities on Exelon’s and Generation’s Consolidated Balance Sheets.

(b) Represents a purchase accounting adjustment to the fair value of the CENG ARO liability as of April 1, 2014, the date of consolidation. See Note 6 — Investment in Constellation Energy Nuclear Group, LLC for additional information.

Unrealized Gains (Losses) on nuclear decommissioning trust funds

The following table provides unrealized gains on NDT funds for the three months ended March 31, 2015 and 2014:

	Exelon and Generation
	Three Months Ended March 31,
	2015		2014
Net unrealized gains on decommissioning trust      funds — Regulatory Agreement Units(a)	$	48	$	61
Net unrealized gains on decommissioning trust      funds — Non-Regulatory Agreement Units(b)(c)	40		13

(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 $10 million of net unrealized gains related to the Zion Station pledged assets for the three months ended March 31, 2015 and 2014. 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

The following table provides the pledged assets and payables to ZionSolutions, and withdrawals by ZionSolutions at March 31, 2015 and December 31, 2014:

	Exelon and Generation
	March 31, 2015		December 31, 2014
Carrying value of Zion Station pledged assets	$	308	$	319
Payable to Zion Solutions(a)	281		292
Current portion of payable to Zion Solutions(b)	145		137
Cumulative withdrawals by Zion Solutions to pay decommissioning costs	687		666

(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.