Retirement Benefits and Trusteed Assets (Pension Plan - Pension Cost Inclusions) (Details) - Pension Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 100	$ 83	$ 94
Interest cost	210	212	192
Expected return on plan assets	(296)	(273)	(266)
Amortization of net actuarial loss	205	157	208
Special termination benefits	2	0	0
Net cost (credit)	221	179	228
DTE Electric
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	77	64	73
Interest cost	160	162	146
Expected return on plan assets	(210)	(194)	(184)
Amortization of net actuarial loss	147	110	148
Prior service cost	1	2	1
Special termination benefits	1	0	0
Net cost (credit)	$ 176	$ 144	$ 184