Income Taxes (Income Tax Expense Varied from Statutory Federal Income Tax Rate) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Amount
Income tax expense at U.S. Federal Statutory Tax Rate	$ 326	$ 288	$ 329
Tax Credits
Production tax credits	(161)	(174)	(91)
Investment tax credits	(94)	(128)	(44)
Other	(5)	(4)	(5)
Other Adjustments
TCJA regulatory liability amortization	(65)	(66)	(63)
Other	(4)	4	0
Nontaxable or Nondeductible Items
AFUDC equity	(20)	(17)	(7)
Other	6	(3)	(4)
Changes in Tax Laws or Rates Enacted in the Current Period	16	0	0
Changes in Valuation Allowances	7	6	0
Changes in Prior Year Unrecognized Tax Benefits	0	0	(12)
Foreign Tax Effects	1	1	0
State and Local Income Taxes, Net of Federal Effect	81	59	66
Income Tax Expense (Benefit) at Effective Tax Rate	$ 88	$ (34)	$ 169
Percentage
Income tax expense at U.S. Federal Statutory Tax Rate	21.00%	21.00%	21.00%
Tax Credits
Production tax credits	(10.40%)	(12.70%)	(5.80%)
Investment tax credits	(6.10%)	(9.30%)	(2.80%)
Other	(0.30%)	(0.30%)	(0.30%)
Other Adjustments
TCJA regulatory liability amortization	(4.20%)	(4.80%)	(4.00%)
Other	(0.10%)	0.20%	0.00%
Nontaxable or Nondeductible Items
AFUDC equity	(1.30%)	(1.20%)	(0.50%)
Other	0.50%	(0.30%)	(0.20%)
Changes in Tax Laws or Rates Enacted in the Current Period	1.00%	0.00%	0.00%
Changes in Valuation Allowances	0.40%	0.50%	0.00%
Changes in Prior Year Unrecognized Tax Benefits	0.00%	0.00%	(0.80%)
Foreign Tax Effects	0.00%	0.10%	0.00%
State and Local Income Taxes, Net of Federal Effect	5.20%	4.30%	4.20%
Income Tax Expense (Benefit) at Effective Tax Rate	5.70%	(2.50%)	10.80%
ILLINOIS
Nontaxable or Nondeductible Items
State and Local Income Taxes, Net of Federal Effect	$ 14
DTE Electric
Amount
Income tax expense at U.S. Federal Statutory Tax Rate	257	$ 218	$ 179
Tax Credits
Production tax credits	(77)	(167)	(79)
Investment tax credits	(95)	(70)	(1)
Other	(4)	(4)	(4)
Other Adjustments
TCJA regulatory liability amortization	(53)	(55)	(53)
Other	(1)	2	0
Nontaxable or Nondeductible Items
AFUDC equity	(20)	(16)	(7)
Other	(2)	(2)	(2)
Changes in Valuation Allowances	0	5	0
Changes in Prior Year Unrecognized Tax Benefits	0	0	(7)
State and Local Income Taxes, Net of Federal Effect	66	57	52
Income Tax Expense (Benefit) at Effective Tax Rate	$ 71	$ (32)	$ 78
Percentage
Income tax expense at U.S. Federal Statutory Tax Rate	21.00%	21.00%	21.00%
Tax Credits
Production tax credits	(6.30%)	(16.00%)	(9.30%)
Investment tax credits	(7.70%)	(6.70%)	(0.10%)
Other	(0.40%)	(0.40%)	(0.50%)
Other Adjustments
TCJA regulatory liability amortization	(4.40%)	(5.30%)	(6.20%)
Other	(0.10%)	0.20%	0.00%
Nontaxable or Nondeductible Items
AFUDC equity	(1.60%)	(1.60%)	(0.80%)
Other	(0.10%)	(0.20%)	(0.20%)
Changes in Valuation Allowances	0.00%	0.40%	0.00%
Changes in Prior Year Unrecognized Tax Benefits	0.00%	0.00%	(0.80%)
State and Local Income Taxes, Net of Federal Effect	5.40%	5.50%	6.10%
Income Tax Expense (Benefit) at Effective Tax Rate	5.80%	(3.10%)	9.20%