Significant Accounting Policies (Intangible Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Finite-Lived Intangible Assets [Line Items]
Accumulated Amortization	$ (137)	$ (119)
Indefinite-lived Intangible Assets [Line Items]
Intangible assets not subject to amortization	19	17
DTE Energy Long-term intangible assets
Gross Carrying Value	325	263
Accumulated Amortization	(137)	(119)
Net Carrying Value	188	144
Carbon offsets
Indefinite-lived Intangible Assets [Line Items]
Intangible assets not subject to amortization	16	14
Renewable energy credits
Indefinite-lived Intangible Assets [Line Items]
Intangible assets not subject to amortization	0	1
Other
Indefinite-lived Intangible Assets [Line Items]
Intangible assets not subject to amortization	3	2
Contract intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	306	246
Accumulated Amortization	(137)	(119)
Net Carrying Value	169	127
DTE Energy Long-term intangible assets
Accumulated Amortization	$ (137)	$ (119)
Contract intangibles | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful Lives	5 years
Contract intangibles | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful Lives	39 years