XML 106 R122.htm IDEA: XBRL DOCUMENT v2.4.0.6
Retirement Benefits and Trusteed Assets (Details Textuals) (USD $)
In Millions, unless otherwise specified
 12 Months Ended 1 Months Ended 3 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended
Dec. 31, 2011
percent
years
Dec. 31, 2010
Dec. 31, 2009
Jan. 31, 2012
Pension Plans, Defined Benefit [Member]
Jan. 31, 2011
Pension Plans, Defined Benefit [Member]
Dec. 31, 2011
Pension Plans, Defined Benefit [Member]
Dec. 31, 2011
Pension Plans, Defined Benefit [Member]
Dec. 31, 2010
Pension Plans, Defined Benefit [Member]
Jan. 31, 2012
Other Postretirement Benefit Plans, Defined Benefit [Member]
Dec. 31, 2011
Other Postretirement Benefit Plans, Defined Benefit [Member]
Dec. 31, 2010
Other Postretirement Benefit Plans, Defined Benefit [Member]
Dec. 31, 2010
DTE Energy [Member]
Dec. 31, 2010
Detroit Edison [Member]
Dec. 31, 2010
MichCon [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]                            
Transfers between Level 2 and Level 3           $ 0 $ 0     $ 0 $ 0      
Transfers between Level 1 and Level 2           0 0     0 0      
Health Care Trend Increase in Percentage Point 1                          
Company contributions       240 200   209 206 140 111 160      
Company Lowered Percentage of Long Term Rate of Return Assumption for Pension Plans 8.25%                          
Defined Contribution Plan, Cost Recognized 35 34 33                      
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year 120                          
Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components 35                          
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation 306                          
Health Care Trend Decrease in Percentage Point 1                          
Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components 23                          
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation 297                          
Net Impact of Remeasurement of Deferred Tax Assets and Liabilities Related to Health Care Legislation Acts                       22 18 3
Prescription Drug Benefit, Effect of Subsidy on Net Periodic Postretirement Benefit Cost 6 7 20                      
Prescription Drug Subsidy Receipts, Year One 6                          
Grantor Trust Balance $ 13                          
Time period to pay benefit payments for qualified and unqualified plans 5                          
Time period for aggregate benefit payments for qualified and non qualtified benefit plans 5