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