Significant Accounting Policies (Roll-Forward of Activity for Financing Receivables Credit Loss Reserves) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($)
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 91
Current period provision	75
Write-offs charged against allowance	(120)
Recoveries of amounts previously written off	41
Ending balance	87
Trade accounts receivable
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	87
Current period provision	73
Write-offs charged against allowance	(117)
Recoveries of amounts previously written off	41
Ending balance	84
Other receivables
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	4
Current period provision	2
Write-offs charged against allowance	(3)
Recoveries of amounts previously written off	0
Ending balance	3
DTE Electric
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	46
Current period provision	47
Write-offs charged against allowance	(68)
Recoveries of amounts previously written off	24
Ending balance	$ 49