Regulatory Matters (Narrative) (Details) (USD $)						1 Months Ended												1 Months Ended
	Sep. 30, 2011	Dec. 31, 2010	Jun. 30, 2011 Consumers Energy Company [Member] 2010 Electric Rate Case [Member]	Dec. 31, 2010 Consumers Energy Company [Member] 2010 Electric Rate Case [Member]	Jun. 30, 2011 2011 Electric Rate Case [Member] Consumers Energy Company [Member]	Jun. 30, 2011 Power Supply Cost Recover (PSCR) [Member] Consumers Energy Company [Member]	Sep. 30, 2011 Consumers Energy Company [Member] Electric Decoupling [Member]	Mar. 31, 2011 Consumers Energy Company [Member] Electric Decoupling [Member]	Mar. 31, 2011 Consumers Energy Company [Member] Uncollectible Expense Tracking Mechanism [Member]	Jun. 30, 2011 Consumers Energy Company [Member] Electric Operation and Maintenance Show-Cause Order [Member]	Dec. 31, 2009 Consumers Energy Company [Member] Electric Operation and Maintenance Show-Cause Order [Member]	May 31, 2011 2010 Gas Rate Case [Member] Consumers Energy Company [Member]	Feb. 28, 2011 2010 Gas Rate Case [Member] Consumers Energy Company [Member]	Jan. 31, 2011 2010 Gas Rate Case [Member] Consumers Energy Company [Member]	Aug. 31, 2010 2010 Gas Rate Case [Member] Consumers Energy Company [Member]	Sep. 30, 2011 2011 Gas Rate Case [Member] Consumers Energy Company [Member]	Sep. 30, 2011 Consumers Energy Company [Member] Gas Decoupling [Member]	Sep. 30, 2011 Consumers Energy Company [Member] Big Rock Decommissioning [Member]	Jul. 31, 2011 Consumers Energy Company [Member] Big Rock Decommissioning [Member]	Apr. 30, 2010 Consumers Energy Company [Member] Big Rock Decommissioning [Member]	Feb. 28, 2010 Consumers Energy Company [Member] Big Rock Decommissioning [Member]	Jun. 30, 2011 Consumers Energy Company [Member] Electric Plant [Member]	Feb. 28, 2010 Consumers Energy Company [Member] Consumers Share of Ludington [Member]	Oct. 31, 2011 Consumers Energy Company [Member]	Sep. 30, 2011 Consumers Energy Company [Member]	Jun. 30, 2011 Consumers Energy Company [Member]	May 31, 2011 Consumers Energy Company [Member]	Apr. 30, 2011 Consumers Energy Company [Member]	Dec. 31, 2010 Consumers Energy Company [Member]
Annual Rate Increase Authorized by the MPSC				$ 146,000,000								$ 31,000,000
Annual Rate Increase Requested by Consumers					195,000,000										55,000,000	49,000,000
Difference Between the Annual Rate Increase Authorized by MPSC and the Annual Rate Increase Self-implemented by Consumers				4,000,000
Amount of rates to be refunded to customers			0							0
Requested Recovery								27,000,000	3,000,000								16,000,000
Regulatory assets	2,002,000,000	2,093,000,000					55,000,000										16,000,000	85,000,000							2,002,000,000				2,093,000,000
Litigation Settlement, Gross																			120,000,000
Proposed Refund Of Spent Nuclear Fuel Disposal Costs Collected																		23,000,000
Remaining Portion of Litigation Settlement																		12,000,000
Percentage of Difference Between Rate Base Expense and Actual Expense To Collect/Refund									80.00%
Difference Between the Operation and Maintenance Expenditures Ordered by the MPSC and the Operation and Maintenance Expenditures Incurred by Consumers During 2007											14,000,000
Imposed fine by MPSC										65,200
Contributions to Fund Decommissioning Costs																					44,000,000
Revenue Collected in Excess of Costs to Decommission Big Rock, Plus Interest, and Ordered for Refund																				85,000,000
Amount Paid to Transfer Ownership and Responsibility																		30,000,000
Nuclear Fuel Storage Costs Incurred as a Result of the DOE's Failure to Accept Spent Nuclear Fuel																		55,000,000
Recommended Disallowance of Renewable Energy Plan Expenditures																										3,000,000
Annual Amount Of Reduction Of Renewable Energy Plan Surcharge Billed To Customers																											54,000,000
Proposed Annual Amount Of Reduction Of Renewable Energy Plan Surcharge Billed To Customers																								3,000,000
Authorized Energy Optimization Incentive for Exceeding 2009 Savings Targets																											6,000,000
Requested Energy Optimization Incentive for Exceeding 2010 Savings Targets																												8,000,000
Increase in Annual Depreciation Requested by Consumers																							9,000,000
Increase in Annual Depreciation Expense Authorized by the MPSC																						19,000,000
Rate of Return on Equity Requested by Consumers					10.70%										11.00%	10.70%
Rate of Return On Equity Authorized by the MPSC												10.50%
Net Over/(Under) Recovery, Including Interest, Authorized by the MPSC						(31,000,000)
Amount Of Proposed Self-implemented Rate Increase														48,000,000
Revised Amount Of Proposed Self-implemented Rate Increase													$ 29,000,000