Significant Accounting Policies (Financing Receivables Classified by Internal Grade of Credit Risk) (Details) $ in Millions	Mar. 31, 2020 USD ($)
Notes receivable
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 12
2019	40
2018 and prior	16
Total	68
Notes receivable | Internal grade 1
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2
2019	9
2018 and prior	9
Total	20
Notes receivable | Internal grade 2
Financing Receivable, Credit Quality Indicator [Line Items]
2020	10
2019	31
2018 and prior	7
Total	48
Net investment in leases
Financing Receivable, Credit Quality Indicator [Line Items]
2020	133
2019	0
2018 and prior	44
Total	177
Net investment in leases | Internal grade 1
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018 and prior	43
Total	43
Net investment in leases | Internal grade 2
Financing Receivable, Credit Quality Indicator [Line Items]
2020	133
2019	0
2018 and prior	1
Total	134
DTE Electric | Notes receivable
Financing Receivable, Credit Quality Indicator [Line Items]
Total	11
DTE Electric | Notes receivable | Internal grade 1
Financing Receivable, Credit Quality Indicator [Line Items]
Total	11
DTE Electric | Notes receivable | Internal grade 2
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0
DTE Electric | Net investment in leases
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0
DTE Electric | Net investment in leases | Internal grade 1
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0
DTE Electric | Net investment in leases | Internal grade 2
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 0