Commitments and Contingencies (Other Commitments) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013
Midwest Generation LLC \| Capital addition purchase commitments
Other Commitments
Minimum commitments, Remainder of 2013	$ 8
Minimum commitments, 2014	1
Midwest Generation LLC \| Other contractual obligations
Other Commitments
Minimum commitments, Remainder of 2013	4
Minimum commitments, 2014	15
Total Minimum commitments	19
Other EME Subsidiaries \| Other contractual obligations
Other Commitments
Minimum commitments, Remainder of 2013	5
Minimum commitments, 2014	31
Minimum commitments, 2015	27
Minimum commitments, 2016	17
Minimum commitments, 2017	7
Minimum commitments, after 2017	1
Total Minimum commitments	$ 88

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fifth fiscal year following the latest fiscal year.

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 47

-Paragraph 7

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the four fiscal year following the latest fiscal year.

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the second fiscal year following the latest fiscal year.

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the third fiscal year following the latest fiscal year.

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- Definition

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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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing after the fifth fiscal year following the latest fiscal year.

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the remainder of the fiscal year following the latest fiscal year ended.

+ References

No definition available.

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