Commitments and Contingencies (Details Textuals) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2012 years people kWh weeks employees facilities	Dec. 31, 2011
Loss Contingencies [Line Items]
Environmental Capital Expenditures Through Current Year		$ 1,700,000,000
Environmental Capital Expenditures in Current Year	170,000,000
Environmental Capital Expenditures In Future Years	2,000,000,000
EPA is Alleging Detroit Edison Power Plants Violated New Source Performance Standards	5
Possible Additional Capital Expenditures for EPA Regulations	80,000,000	55,000,000
Minimum Amount of Years to Incur Additional Capital Expenditures	4
Maximum Amount of Years to Incur Additional Capital Expenditures	6
Period Gas Utility Can Amortize MGP Costs	10
Company will Pay a Fine to the EPA to Settle Air and Water Issues	1,750,000
Possible Environmental Capital Expenditures to Comply with Requirements	1,500,000
Capital Expenditures Over the Next Few Years	23,000,000
Time Period to Comply with Applicable MACT Standards	3
Number of Defendant Oil Power and Coal Companies In Domestic District Court on Basis of Which Company Named	24
Number of People In Country Claiming Business Activities Contributing to Global Warming Higher Temperatures and Storm Activity	400
Costs Associated with Relocating Village and Unspecified Attorney's Fees and Expenses	400,000,000
Waiting Period of Policy	12
Insurance Coverage for Extra Expense when to Necessitate Power Plant when Unavailable	490,000,000
Period of Coverage of Policy for Extra Expenses	3
Primary Coverage	500,000,000
Coverage for Stabilization Decontamination Debris Removal Repair and Replacement of Property and Decommissioning	2,250,000,000
Combined Coverage Limit for Total Property Damage	2,750,000,000
Insurance Deductible for Nuclear Power Plant	1,000,000
NEIL Policies Against Terrorism Loss	3,200,000,000
Amount per Event Loss Associated with Nuclear Power Plants	31,000,000
Maintenance of Public Liability Insurance for Nuclear Power Plants	375,000,000
Aggregate Limit of Liabilities Arises From Terrorist Act Outside Scope of Trials Subject to One Industry	300,000,000
Deferred Premium Charged Levied Against Each Licensed Nuclear Facility	117,500,000
Limit Deferred Premium Charges Per Year	17,500,000
Company Obligated to Pay DOE Fee of Fermi 2 Electricity Generated and Sold	1
Payment from the DOE for Delaying Acceptance of Spent Nuclear Fuel	48,000,000
Guarantee Obligations Maximum Exposure One	10,000,000
Performance Bonds Outstanding	39,000,000
Number of Represented Employees	5,000
Contract Expiring for Electrical Linemen	500
Long-term Purchase Commitment, Amount	5,300,000,000
Estimated Future Capital Expenditures for Current Year	2,100,000,000
Electric Utility [Member]
Loss Contingencies [Line Items]
Number of Former MGP Sites	3
Accrued for Remediation Related to the Sites	8,000,000	8,000,000
Gas Utility [Member]
Loss Contingencies [Line Items]
Number of Former MGP Sites	15
Accrued for Remediation Related to the Sites	38,000,000	36,000,000
Synthetic Fuel [Member]
Loss Contingencies [Line Items]
Days Obligations will Survive After Expiration of All Applicable Statutes of Limitations	90
Guarantor Obligations, Maximum Exposure, Undiscounted	1,200,000,000
Emissions [Member]
Loss Contingencies [Line Items]
Days Obligations will Survive After Expiration of All Applicable Statutes of Limitations		90
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 61,000,000