Commitments and Contingencies - Fuel Purchase Obligations (Details) $ in Millions	Jun. 30, 2015 USD ($)
Exelon Generation Co L L C [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	$ 1,893
2015	283
2016	583
2017	410
2018	185
2019	130
Thereafter	302
Exelon Generation Co L L C [Member] \| Public Utilities, Inventory, Fuel [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	8,884
2015	726
2016	1,129
2017	1,078
2018	969
2019	880
Thereafter	4,102
PECO Energy Co [Member] \| Public Utilities, Inventory, Fuel [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	375
2015	65
2016	107
2017	66
2018	46
2019	20
Thereafter	71
Baltimore Gas and Electric Company [Member] \| Public Utilities, Inventory, Fuel [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	622
2015	52
2016	103
2017	92
2018	69
2019	61
Thereafter	$ 245

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 440

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308

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Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of the unrecorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts).

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Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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