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Nuclear Decommissioning (Tables)

3 Months Ended

Mar. 31, 2014

Schedule Of Nuclear Decommissioning [Line Items]

Nuclear decommissioning asset retirement obligation rollforward

Nuclear decommissioning ARO at December 31, 2013 ^(a)	$	4,855
Accretion expense(a)		66
Costs incurred to decommission retired plants		(1)
Nuclear decommissioning ARO at March 31, 2014 ^(a)	$	4,920

(a) Includes $9 million as the current portion of the ARO at March 31, 2014 and December 31, 2013 which is included in Other current liabilities on Exelon's and Generation's Consolidated Balance Sheets.

Unrealized Gains (Losses) on nuclear decommissioning trust funds

		Three Months Ended
		March 31,
			2014		2013
Net unrealized gains on decommissioning trust funds —
	Regulatory Agreement Units ^(a)	$	61	$	195
Net unrealized gains on decommissioning trust funds —
	Non-Regulatory Agreement Units ^(b)(c)		13		64

(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 and $2 million of net unrealized gains related to the Zion Station pledged assets for the three months ended March 31, 2014 and 2013, respectively. Net unrealized gains (losses) 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

	Exelon and Generation
	March 31,		December 31,
	2014		2013
Carrying value of Zion Station pledged assets	$	429	$	458
Payable to Zion Solutions ^(a)		385		414
Current portion of payable to Zion Solutions ^(b)		103		109
Withdrawals by Zion Solutions to pay decommissioning costs ^(c)		537		498

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.
Included in Other current liabilities within Exelon's and Generation's Consolidated Balance Sheets.
Cumulative withdrawals since September 1, 2010.

Exelon Generation Co L L C [Member]

Schedule Of Nuclear Decommissioning [Line Items]

Nuclear decommissioning asset retirement obligation rollforward

Nuclear decommissioning ARO at December 31, 2013 ^(a)	$	4,855
Accretion expense(a)		66
Costs incurred to decommission retired plants		(1)
Nuclear decommissioning ARO at March 31, 2014 ^(a)	$	4,920

Unrealized Gains (Losses) on nuclear decommissioning trust funds

		Three Months Ended
		March 31,
			2014		2013
Net unrealized gains on decommissioning trust funds —
	Regulatory Agreement Units ^(a)	$	61	$	195
Net unrealized gains on decommissioning trust funds —
	Non-Regulatory Agreement Units ^(b)(c)		13		64

Zion Station pledged assets

	Exelon and Generation
	March 31,		December 31,
	2014		2013
Carrying value of Zion Station pledged assets	$	429	$	458
Payable to Zion Solutions ^(a)		385		414
Current portion of payable to Zion Solutions ^(b)		103		109
Withdrawals by Zion Solutions to pay decommissioning costs ^(c)		537		498

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.
Included in Other current liabilities within Exelon's and Generation's Consolidated Balance Sheets.
Cumulative withdrawals since September 1, 2010.