Average Maturity of Debt Securities

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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash

-URI http://asc.fasb.org/extlink&oid=6506951

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash Equivalents

-URI http://asc.fasb.org/extlink&oid=6507016

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- Definition

Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bb)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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- Definition

Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

+ References

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- Definition

Amount of transfers of liabilities measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

+ References

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- Definition

Amount of transfers of liabilities measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

+ References

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- Definition

Amount of transfers of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset) into (out of) level 3 of the fair value hierarchy.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19279-110258

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- Definition

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.

+ References

No definition available.

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Trading Securities

-URI http://asc.fasb.org/extlink&oid=6526789

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 35

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24584-111560

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Available-for-Sale Securities

-URI http://asc.fasb.org/extlink&oid=6505594

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph a, f, g

-Article 7

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- Definition

Amount after tax of reclassification adjustments of other comprehensive income (loss).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 14A

-URI http://asc.fasb.org/extlink&oid=36458714&loc=SL7669686-108580

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 55

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=51821188&loc=d3e1436-108581

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- Definition

Amount of gain (loss) realized from securities classified as trading.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.7(c))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Trading Securities

-URI http://asc.fasb.org/extlink&oid=6526789

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Fair Value (Details Textuals) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
Fair Value (Details Textuals) - USD ($)	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Fair Value, Option, Quantitative Disclosures [Line Items]
Assets Level 1 to Level 2	$ 0	$ 0	$ 0	$ 0
Assets Level 2 to Level 1	0	0	0	0
Liabilities Level 1 to Level 2	0	0	0	0
Liabilities Level 2 to Level 1	0	0	0	0
Trading securities realized gain (loss)			1,000,000	8,000,000
Accumulated Net Unrealized Investment Gain (Loss)
Fair Value, Option, Quantitative Disclosures [Line Items]
Unrealized losses on available for sale securities	0	0	0	0
DTE Electric
Fair Value, Option, Quantitative Disclosures [Line Items]
Transfers between Level 3			0	0
Trading securities realized gain (loss)			1,000,000	7,000,000
DTE Electric \| Accumulated Net Unrealized Investment Gain (Loss)
Fair Value, Option, Quantitative Disclosures [Line Items]
Unrealized losses on available for sale securities	0	$ 0	0	$ 0
DTE Electric \| Nuclear decommissioning trust fund
Fair Value, Option, Quantitative Disclosures [Line Items]
Cash and cash equivalents	7,000,000		$ 7,000,000		$ 11,000,000
Average maturity of debt securities			6 years		7 years
Recurring
Fair Value, Option, Quantitative Disclosures [Line Items]
Cash and cash equivalents	12,000,000		$ 12,000,000		$ 112,000,000
Recurring \| DTE Electric
Fair Value, Option, Quantitative Disclosures [Line Items]
Cash and cash equivalents	7,000,000		7,000,000		104,000,000
Restricted assets \| Recurring
Fair Value, Option, Quantitative Disclosures [Line Items]
Cash and cash equivalents	5,000,000		5,000,000		105,000,000
Restricted assets \| Recurring \| DTE Electric
Fair Value, Option, Quantitative Disclosures [Line Items]
Cash and cash equivalents					96,000,000
Other investments \| Recurring
Fair Value, Option, Quantitative Disclosures [Line Items]
Cash and cash equivalents	7,000,000		7,000,000		7,000,000
Other investments \| Recurring \| DTE Electric
Fair Value, Option, Quantitative Disclosures [Line Items]
Cash and cash equivalents					8,000,000
Other investments \| Recurring \| Equity
Fair Value, Option, Quantitative Disclosures [Line Items]
Other investments	$ 149,000,000		$ 149,000,000		$ 150,000,000