Significant Accounting Policies (Roll-Forward of Activity for Financing Receivables Credit Loss Reserves) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 91
Current period provision	35	$ 29
Write-offs charged against allowance	(52)
Recoveries of amounts previously written off	16
Ending balance	90
Trade accounts receivable
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	87
Current period provision	34
Write-offs charged against allowance	(51)
Recoveries of amounts previously written off	16
Ending balance	86
Other receivables
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	4
Current period provision	1
Write-offs charged against allowance	(1)
Recoveries of amounts previously written off	0
Ending balance	4
DTE Electric
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	46
Current period provision	17	$ 16
Write-offs charged against allowance	(30)
Recoveries of amounts previously written off	10
Ending balance	$ 43