Significant Accounting Policies (Financing Receivables Classified by Internal Grade of Credit Risk) (Details) $ in Millions	Sep. 30, 2024 USD ($)
Notes receivable
Financing receivables by year of origination
2024	$ 426
2023	8
2022 and Prior	29
Total	463
Notes receivable | DTE Electric
Financing receivables by year of origination
Total	2
Notes receivable | Internal grade 1
Financing receivables by year of origination
2024	0
2023	1
2022 and Prior	4
Total	5
Notes receivable | Internal grade 1 | DTE Electric
Financing receivables by year of origination
Total	1
Notes receivable | Internal grade 2
Financing receivables by year of origination
2024	426
2023	7
2022 and Prior	25
Total	458
Notes receivable | Internal grade 2 | DTE Electric
Financing receivables by year of origination
Total	1
Net investment in leases
Financing receivables by year of origination
2024	160
2023	0
2022 and Prior	279
Total	439
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
2024	0
2023	0
2022 and Prior	36
Total	36
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
2024	160
2023	0
2022 and Prior	243
Total	403
Net investment in leases | Internal grade 2 | DTE Electric
Financing receivables by year of origination
Total	$ 0