Significant Accounting Policies (Intangible Assets) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 170	$ 168
Less accumulated amortization	60	57
Intangible assets, net	110	111
Less current intangible assets	10us-gaap_IntangibleAssetsCurrent	9us-gaap_IntangibleAssetsCurrent
Intangible assets	100us-gaap_FiniteLivedIntangibleAssetsNet	102us-gaap_FiniteLivedIntangibleAssetsNet
DTE Electric
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	47	46
Less current intangible assets	10	9
Intangible assets	37	37
Renewable energy credits
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	46	45
Renewable energy credits \| DTE Electric
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	46	45
Contract intangible assets
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	123	122
Emission allowances
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, gross	1	1
Emission allowances \| DTE Electric
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, gross	$ 1	$ 1

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.

+ References

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

-Publisher FASB

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The current portion of nonphysical assets, excluding financial assets, if these assets are classified into the current and noncurrent portions.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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Amount before accumulated amortization of intangible assets, excluding goodwill.

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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

+ References

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-Publisher FASB

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