Nuclear Decommissioning (Tables)

3 Months Ended

Mar. 31, 2018

Schedule Of Nuclear Decommissioning [Line Items]

Schedule of Financial Instruments Owned and Pledged as Collateral [Table Text Block]

The following table provides the pledged assets and payables to ZionSolutions, and withdrawals by ZionSolutions at March 31, 2018 and December 31, 2017:

	Exelon and Generation
	March 31, 2018		December 31, 2017
Carrying value of Zion Station pledged assets(a)	$	30	$	39
Payable to Zion Solutions(b)(c)	28		37
Cumulative withdrawals by Zion Solutions to pay decommissioning costs(d)	949		942

_________

(a) Included in Other current assets within Exelon's and Generation's Consolidated Balance sheets.

(b) 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.

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

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

^{[1],[2],[3],[4]}

Schedule of Change in Asset Retirement Obligation [Table Text Block]

The following table provides a rollforward of the nuclear decommissioning ARO reflected on Exelon’s and Generation’s Consolidated Balance Sheets from December 31, 2017 to March 31, 2018:

Nuclear decommissioning ARO at December 31, 2017(a)	$	9,662
Accretion expense	117
Net increase due to changes in, and timing of, estimated future cash flows	32
Costs incurred related to decommissioning plants	(4		)
Nuclear decommissioning ARO at March 31, 2018(a)	$	9,807

_________

(a) Includes $64 million and $13 million for the current portion of the ARO at March 31, 2018 and December 31, 2017, respectively, which is included in Other current liabilities on Exelon’s and Generation’s Consolidated Balance Sheets.

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Unrealized Gain (Loss) on Investments [Table Text Block]

The following table provides net unrealized gains (losses) on NDT funds for the three months ended March 31, 2018 and 2017:

	Exelon and Generation
	Three Months Ended March 31,
	2018			2017
Net unrealized gains (losses) on decommissioning trust funds — Regulatory Agreement Units(a)	$	(75	)	$	222
Net unrealized gains (losses) on decommissioning trust funds — Non-Regulatory Agreement Units(b)(c)	(96		)	166

_________

(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 $(2) million and $(1) million of net unrealized losses related to the Zion Station pledged assets for the three months endedMarch 31, 2018 and 2017, respectively. Net unrealized losses related to Zion Station pledged assets are included in Other current liabilities on Exelon’s and Generation’s Consolidated Balance Sheets in 2018 and 2017, respectively.

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

^[6],[7],[8]

[1] 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.

[2] Included in Other current assets within Exelon's and Generation's Consolidated Balance sheets.

[3] Included in Other current liabilities within Exelon’s and Generation’s Consolidated Balance Sheets.

[4] Includes project expenses to decommission Zion Station and estimated tax payments on Zion Station NDT fund earnings

[5] Includes $64 million and $13 million for the current portion of the ARO at March 31, 2018 and December 31, 2017, respectively, which is included in Other current liabilities on Exelon’s and Generation’s Consolidated Balance Sheets.

[6] Excludes $(2) million and $(1) million of net unrealized losses related to the Zion Station pledged assets for the three months ended March 31, 2018 and 2017, respectively. Net unrealized losses related to Zion Station pledged assets are included in Other current liabilities on Exelon’s and Generation’s Consolidated Balance Sheets in 2018 and 2017, respectively.

[7] 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.

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