Long-Term Debt (Debt Issuances) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013 Electric [Member] Senior Notes [Member]	Apr. 30, 2013 Gas [Member] Senior Notes [Member]	Mar. 31, 2013 Thirty Years [Member] Electric [Member] Mortgages [Member]	Aug. 31, 2013 Eleven Years [Member] Electric [Member] Mortgages [Member]	Nov. 30, 2013 Ten Years [Member] DTE Energy [Member] Senior Notes [Member]	Sep. 30, 2013 Ten Years [Member] Gas [Member] Mortgages [Member]	Sep. 30, 2013 Twelve Years [Member] Gas [Member] Mortgages [Member]	Sep. 30, 2013 Fifteen Years [Member] Gas [Member] Mortgages [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		6.40%	5.26%	4.00%	3.65%	3.85%	3.64%	3.74%	3.94%
Debt Instrument, Face Amount	$ 1,245			$ 375	$ 400	$ 300	$ 50	$ 70	$ 50