Long-Term Debt (Debt Issuances) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 1,300
DTE Energy [Member] | Senior Notes [Member] | May 2014 3.50% Senior Notes Maturing in 2024 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.50%
Debt Instrument, Face Amount	350
Electric [Member] | Mortgages [Member] | June 2014 3.77% Mortgage Bonds Maturing in 2026 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.77%
Debt Instrument, Face Amount	100
Electric [Member] | Mortgages [Member] | June 2014 4.60% Mortgage Bonds Maturing in 2044 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.60%
Debt Instrument, Face Amount	150
Electric [Member] | Mortgages [Member] | July 2014 3.375% Mortgage Bonds Maturing in 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.375%
Debt Instrument, Face Amount	350
Electric [Member] | Mortgages [Member] | July 2014 4.30% Mortgage Bonds Maturing in 2044 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.30%
Debt Instrument, Face Amount	$ 350