Nuclear Decommissioning (Tables)

12 Months Ended

Dec. 31, 2013

Schedule Of Nuclear Decommissioning [Line Items]

Nuclear decommissioning asset retirement obligation rollforward

		Exelon and Generation
Nuclear decommissioning ARO at January 1, 2012	$	3,680
Accretion expense		231
Net increase due to changes in, and timing of, estimated future cash flows		833
Costs incurred to decommission retired plants		(3)
Nuclear decommissioning ARO at December 31, 2012 (a)		4,741
Accretion expense		259
Net decrease due to changes in, and timing of, estimated future cash flows		(140)
Costs incurred to decommission retired plants		(5)
Nuclear decommissioning ARO at December 31, 2013 (a)	$	4,855

(a) Includes $9million and$10 million as the current portion of the ARO at December 31, 2013and 2012, respectively, which isincluded in Othercurrent liabilities on Exelon's and Generation's Consolidated Balance Sheets.

Unrealized Gains (Losses) on nuclear decommissioning trust funds

		Exelon and Generation
		For the Years Ended December 31,
		2013		2012		2011
Net unrealized gains (losses) on decommissioning
	trust funds — Regulatory Agreement Units (a)	$	406	$	386	$	(74)
Net unrealized gains (losses) on decommissioning
	trust funds — Non-Regulatory Agreement Units (b) (c)		146		105		(4)

__________

(a)       Net unrealized gains (losses) 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$7 million, $73million and $48million of net unrealized gainsrelated to the Zion Station pledged assets in 2013, 2012 and 2011, respectively. Net unrealized gains related to Zion Station pledged assets are included inthe Payable for Zion Station decommissioning on Exelon's and Generation's Consolidated Balance Sheets.

(c)       Net unrealized gains (losses) 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

	Exelon and Generation
	2013		2012
Carrying value of Zion Station pledged assets	$	458	$	614
Payable to Zion Solutions (a)		414		564
Current portion of payable to Zion Solutions (b)		109		132
Withdrawals by Zion Solutions to pay decommissioning costs (c)		498		335

(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