Significant Accounting Policies (Financing Receivables Classified by Internal Grade of Credit Risk) (Details) $ in Millions	Dec. 31, 2020 USD ($)
Notes receivable
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 68
2019	57
2018 and prior	16
Total	141
Notes receivable | DTE Electric
Financing Receivable, Credit Quality Indicator [Line Items]
Total	16
Notes receivable | Internal grade 1
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	14
2018 and prior	10
Total	24
Notes receivable | Internal grade 1 | DTE Electric
Financing Receivable, Credit Quality Indicator [Line Items]
Total	14
Notes receivable | Internal grade 2
Financing Receivable, Credit Quality Indicator [Line Items]
2020	68
2019	43
2018 and prior	6
Total	117
Notes receivable | Internal grade 2 | DTE Electric
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2
Net investment in leases
Financing Receivable, Credit Quality Indicator [Line Items]
2020	137
2019	0
2018 and prior	40
Total	177
Net investment in leases | DTE Electric
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0
Net investment in leases | Internal grade 1
Financing Receivable, Credit Quality Indicator [Line Items]
2020	6
2019	0
2018 and prior	39
Total	45
Net investment in leases | Internal grade 1 | DTE Electric
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0
Net investment in leases | Internal grade 2
Financing Receivable, Credit Quality Indicator [Line Items]
2020	131
2019	0
2018 and prior	1
Total	132
Net investment in leases | Internal grade 2 | DTE Electric
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 0