Fair Value (Gains and Losses and Proceeds from the Sale of Securities by the Nuclear Decommissioning Trust Funds) (Details) - DTE Electric - Nuclear Decommissioning Trust Fund - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Realized gains	$ 39	$ 54	$ 83
Realized losses	(33)	(33)	(41)
Proceeds from sales of securities	$ 885	$ 1,146	$ 1,118