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, 2025	Dec. 31, 2024
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning reserve balance	$ 72	$ 63
Current period provision	59	76
Write-offs charged against allowance	(85)	(108)
Recoveries of amounts previously written off	28	41
Ending reserve balance	74	72
DTE Electric
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning reserve balance	46	41
Current period provision	36	49
Write-offs charged against allowance	(55)	(70)
Recoveries of amounts previously written off	19	26
Ending reserve balance	46	46
Trade accounts receivable
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning reserve balance	69	62
Current period provision	59	74
Write-offs charged against allowance	(85)	(108)
Recoveries of amounts previously written off	28	41
Ending reserve balance	71	69
Other receivables
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning reserve balance	3	1
Current period provision	0	2
Write-offs charged against allowance	0	0
Recoveries of amounts previously written off	0	0
Ending reserve balance	$ 3	$ 3