Long-Term Debt (Debt Issuances) (Details)	Sep. 30, 2015 USD ($)
Debt Instrument [Line Items]
Face amount	$ 965,000,000
Senior Notes | June 2015 3.30% Senior Notes Maturing 2022
Debt Instrument [Line Items]
Interest Rate	3.30%
Face amount	$ 300,000,000
DTE Electric | Mortgages | March 2015 3.70% Mortgage Bonds Maturing 2045
Debt Instrument [Line Items]
Interest Rate	3.70%
Face amount	$ 500,000,000
DTE Gas | Mortgages | August 2015 3.35% Mortgage Bonds Maturing in 2027
Debt Instrument [Line Items]
Interest Rate	3.35%
Face amount	$ 40,000,000
DTE Gas | Mortgages | August 2015 4.21% Mortgage Bonds Maturing in 2045
Debt Instrument [Line Items]
Interest Rate	4.21%
Face amount	$ 125,000,000