Significant Accounting Policies (Accumulated Other Comprehensive Loss) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 9,990,000,000	$ 9,499,000,000	$ 8,795,000,000	$ 8,342,000,000
Beginning balance	9,011,000,000
Other comprehensive income	13,000,000	12,000,000	10,000,000
Ending balance	9,990,000,000	9,499,000,000	8,795,000,000
Ending balance	9,512,000,000	9,011,000,000
AOCI including portion attributable to noncontrolling interest
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(120,000,000)	(133,000,000)	(145,000,000)
Other comprehensive income (loss) before reclassifications	(1,000,000)	(3,000,000)
Amounts reclassified from Accumulated other comprehensive income	14,000,000	15,000,000
Other comprehensive income	13,000,000	12,000,000
Ending balance	(120,000,000)	(133,000,000)	(145,000,000)
Net Unrealized Gain (Loss) on Derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(3,000,000)	(4,000,000)	(4,000,000)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from Accumulated other comprehensive income	1,000,000	0
Other comprehensive income	1,000,000	0
Ending balance	(3,000,000)	(4,000,000)	(4,000,000)
Net Unrealized Gain (Loss) on Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(2,000,000)	(3,000,000)	(4,000,000)
Other comprehensive income (loss) before reclassifications	1,000,000	0
Amounts reclassified from Accumulated other comprehensive income	0	1,000,000
Other comprehensive income	1,000,000	1,000,000
Ending balance	(2,000,000)	(3,000,000)	(4,000,000)
Benefit Obligations
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(110,000,000)	(120,000,000)	(131,000,000)
Other comprehensive income (loss) before reclassifications	(3,000,000)	(3,000,000)
Amounts reclassified from Accumulated other comprehensive income	13,000,000	14,000,000
Other comprehensive income	10,000,000	11,000,000
Ending balance	(110,000,000)	(120,000,000)	(131,000,000)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(5,000,000)	(6,000,000)	(6,000,000)
Other comprehensive income (loss) before reclassifications	1,000,000	0
Amounts reclassified from Accumulated other comprehensive income	0	0
Other comprehensive income	1,000,000	0
Ending balance	(5,000,000)	(6,000,000)	(6,000,000)
AOCI attributable to parent
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(120,000,000)	(133,000,000)	(145,000,000)	$ (155,000,000)
Ending balance	(120,000,000)	(133,000,000)	(145,000,000)
Net Unrealized Gain on Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Amounts reclassified from Accumulated other comprehensive income	0	0
DTE Electric
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	5,995,000,000	5,673,000,000	5,196,000,000
Other comprehensive income	1,000,000	0	28,000,000
Ending balance	6,265,000,000	5,995,000,000	5,673,000,000
DTE Electric | AOCI attributable to parent
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	2,000,000	2,000,000	(26,000,000)
Ending balance	3,000,000	2,000,000	$ 2,000,000
DTE Electric | Net Unrealized Gain on Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Amounts reclassified from Accumulated other comprehensive income	$ 0	$ 0