| Schedule of Short-term Debt [Table Text Block] |
| | | | | | | | | | | | | | | | | | DTE Energy | | Detroit Edison | | MichCon | | Total | Unsecured letter of credit facility, expiring in May 2013 | $ | 50 |
| | $ | — |
| | $ | — |
| | $ | 50 |
| Unsecured letter of credit facility, expiring in August 2015 | 125 |
| | — |
| | — |
| | 125 |
| Unsecured revolving credit facility, expiring October 2016 | 1,100 |
| | 300 |
| | 400 |
| | 1,800 |
| Total credit facilities at September 30, 2012 | $ | 1,275 |
| | $ | 300 |
| | $ | 400 |
| | $ | 1,975 |
| Amounts outstanding at September 30, 2012: | | | | | | | | Commercial paper issuances | — |
| | — |
| | 98 |
| | 98 |
| Letters of credit | 188 |
| | — |
| | — |
| | 188 |
| | 188 |
| | — |
| | 98 |
| | 286 |
| Net availability at September 30, 2012 | $ | 1,087 |
| | $ | 300 |
| | $ | 302 |
| | $ | 1,689 |
|
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