Significant Accounting Policies (Roll-Forward of Activity for Financing Receivables Credit Loss Reserves) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2026	Dec. 31, 2025
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning reserve balance	$ 62	$ 72
Current period provision	27	69
Write-offs charged against allowance	(29)	(116)
Recoveries of amounts previously written off	10	37
Ending reserve balance	70	62
DTE Electric
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning reserve balance	41	46
Current period provision	14	44
Write-offs charged against allowance	(20)	(74)
Recoveries of amounts previously written off	6	25
Ending reserve balance	41	41
Trade accounts receivable
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning reserve balance	59	69
Current period provision	27	69
Write-offs charged against allowance	(29)	(116)
Recoveries of amounts previously written off	10	37
Ending reserve balance	67	59
Other receivables
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning reserve balance	3	3
Current period provision	0	0
Write-offs charged against allowance	0	0
Recoveries of amounts previously written off	0	0
Ending reserve balance	$ 3	$ 3