Significant Accounting Policies (Roll-Forward of Activity for Financing Receivables Credit Loss Reserves) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2026	Dec. 31, 2025
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning reserve balance	$ 62	$ 72
Current period provision	76	69
Write-offs charged against allowance	(84)	(116)
Recoveries of amounts previously written off	30	37
Ending reserve balance	84	62
DTE Electric
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning reserve balance	41	46
Current period provision	44	44
Write-offs charged against allowance	(55)	(74)
Recoveries of amounts previously written off	20	25
Ending reserve balance	50	41
Trade accounts receivable
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning reserve balance	59	69
Current period provision	74	69
Write-offs charged against allowance	(84)	(116)
Recoveries of amounts previously written off	30	37
Ending reserve balance	79	59
Other receivables
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning reserve balance	3	3
Current period provision	2	0
Write-offs charged against allowance	0	0
Recoveries of amounts previously written off	0	0
Ending reserve balance	$ 5	$ 3