Significant Accounting Policies (Roll-Forward of Activity for Financing Receivables Credit Loss Reserves) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 104	$ 91
Current period provision	30	35
Write-offs charged against allowance	(36)	(52)
Recoveries of amounts previously written off	25	16
Ending balance	123	90
Trade accounts receivable
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	101	87
Current period provision	30	34
Write-offs charged against allowance	(36)	(51)
Recoveries of amounts previously written off	25	16
Ending balance	120	86
Other receivables
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	3	4
Current period provision	0	1
Write-offs charged against allowance	0	(1)
Recoveries of amounts previously written off	0	0
Ending balance	3	4
DTE Electric
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	57	46
Current period provision	12	17
Write-offs charged against allowance	(24)	(30)
Recoveries of amounts previously written off	14	10
Ending balance	$ 59	$ 43