Significant Accounting Policies (Roll-Forward of Activity for Financing Receivables Credit Loss Reserves) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 104	$ 91
Current period provision	34	103
Write-offs charged against allowance	(61)	(140)
Recoveries of amounts previously written off	38	50
Ending balance	115	104
DTE Electric
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	57	46
Current period provision	17	61
Write-offs charged against allowance	(40)	(80)
Recoveries of amounts previously written off	22	30
Ending balance	56	57
Trade accounts receivable
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	101	87
Current period provision	33	100
Write-offs charged against allowance	(60)	(136)
Recoveries of amounts previously written off	38	50
Ending balance	112	101
Other receivables
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	3	4
Current period provision	1	3
Write-offs charged against allowance	(1)	(4)
Recoveries of amounts previously written off	0	0
Ending balance	$ 3	$ 3