Short-Term Credit Arrangements and Borrowings (Details Textuals) (USD $)
In Millions, unless otherwise specified
 9 Months Ended
Sep. 30, 2012
ratio
banks
percent
Dec. 31, 2011
Short-term Debt [Line Items]    
Revolving Credit Facilities with a Syndicate Number of Banks 20  
Maximum Percentage of Commitment to Bank in Any Facility 8.50%  
Maximum Total Funded Debt to Total Capitalization Ratio 0.65  
Maximum Total Funded Debt to Total Capitalization Ratio Denominator 1  
Letters of Credit Outstanding, Amount $ 91  
Borrowing Capacity Under Financing Agreement with its Clearing Agent 100  
Maximum Additional Margin Financing 50  
Line of Credit Facility, Increase, Additional Borrowings 40  
Line of Credit Facility Current Borrowing 140  
Other Short-term Borrowings $ 71 $ 56
DTE Energy [Member]
    
Short-term Debt [Line Items]    
Total Funded Debt to Total Capitalization Ratio 0.48  
Total Funded Debt to Total Capitalization Ratio Denominator 1  
Detroit Edison [Member]
    
Short-term Debt [Line Items]    
Total Funded Debt to Total Capitalization Ratio 0.52  
Total Funded Debt to Total Capitalization Ratio Denominator 1  
MichCon [Member]
    
Short-term Debt [Line Items]    
Total Funded Debt to Total Capitalization Ratio 0.45  
Total Funded Debt to Total Capitalization Ratio Denominator 1