Significant Accounting Policies (Financing Receivables Classified by Internal Grade of Credit Risk) (Details) $ in Millions	Sep. 30, 2023 USD ($)
Notes receivable
Financing receivables by year of origination
2023	$ 33
2022	85
2021 and Prior	23
Total	141
Notes receivable | DTE Electric
Financing receivables by year of origination
Total	16
Notes receivable | Internal grade 1
Financing receivables by year of origination
2023	14
2022	0
2021 and Prior	6
Total	20
Notes receivable | Internal grade 1 | DTE Electric
Financing receivables by year of origination
Total	16
Notes receivable | Internal grade 2
Financing receivables by year of origination
2023	19
2022	85
2021 and Prior	17
Total	121
Notes receivable | Internal grade 2 | DTE Electric
Financing receivables by year of origination
Total	0
Net investment in leases
Financing receivables by year of origination
2023	0
2022	65
2021 and Prior	222
Total	287
Net investment in leases | DTE Electric
Financing receivables by year of origination
Total	0
Net investment in leases | Internal grade 1
Financing receivables by year of origination
2023	0
2022	0
2021 and Prior	37
Total	37
Net investment in leases | Internal grade 1 | DTE Electric
Financing receivables by year of origination
Total	0
Net investment in leases | Internal grade 2
Financing receivables by year of origination
2023	0
2022	65
2021 and Prior	185
Total	250
Net investment in leases | Internal grade 2 | DTE Electric
Financing receivables by year of origination
Total	$ 0