Regulatory Matters (Narrative) (Details) (USD $)	12 Months Ended			1 Months Ended	12 Months Ended				1 Months Ended				12 Months Ended			12 Months Ended			1 Months Ended	12 Months Ended			1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended					1 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Consumers Energy Company [Member] site	Dec. 31, 2013 Consumers Energy Company [Member] site	Dec. 31, 2012 Consumers Energy Company [Member]	Dec. 31, 2011 Consumers Energy Company [Member]	Nov. 30, 2013 Consumers Energy Company [Member]	May 31, 2013 Electric Rate Case [Member] Consumers Energy Company [Member]	Mar. 31, 2013 Electric Rate Case [Member] Consumers Energy Company [Member]	Jan. 31, 2013 Electric Rate Case [Member] Consumers Energy Company [Member]	Sep. 30, 2012 Electric Rate Case [Member] Consumers Energy Company [Member]	Dec. 31, 2012 Power Supply Cost Recover (PSCR) [Member] Consumers Energy Company [Member]	Dec. 31, 2011 Power Supply Cost Recover (PSCR) [Member] Consumers Energy Company [Member]	May 31, 2013 Power Supply Cost Recover (PSCR) [Member] Consumers Energy Company [Member]	Mar. 31, 2013 Gas Cost Recover (GCR) [Member] Consumers Energy Company [Member]	Mar. 31, 2012 Gas Cost Recover (GCR) [Member] Consumers Energy Company [Member]	May 31, 2013 Gas Cost Recover (GCR) [Member] Consumers Energy Company [Member]	Aug. 31, 2012 2011-2012 Gas Revenue Decoupling Mechanism [Member] Consumers Energy Company [Member]	Dec. 31, 2013 Electric Energy Optimization Plan [Member] Consumers Energy Company [Member]	Dec. 31, 2013 Gas Energy Optimization Plan [Member] Consumers Energy Company [Member]	Jun. 30, 2012 Cancelled Coal-Fueled Plant Costs [Member] Consumers Energy Company [Member]	Dec. 31, 2013 Coal Fueled Electric Generating Units [Member] Consumers Energy Company [Member] site	Dec. 31, 2013 Coal Fueled Electric Generating Units [Member] Consumers Energy Company [Member] site MW	Dec. 31, 2013 Gas Fueled Electric Generating Units [Member] Consumers Energy Company [Member] site	Dec. 31, 2013 Gas Fueled Electric Generating Units [Member] Consumers Energy Company [Member] site	Dec. 31, 2013 Manufactured Gas Plant [Member] Consumers Energy Company [Member] site	Dec. 31, 2013 Gas Storage Inventory Adjustments [Member] Consumers Energy Company [Member]	Dec. 31, 2012 DOE Settlement [Member] Consumers Energy Company [Member]	Dec. 31, 2011 DOE Settlement [Member] Consumers Energy Company [Member]	Jan. 31, 2013 Renewable Energy Grant [Member] Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Energy optimization incentive authorized for exceeding 2012 savings targets								$ 17,000,000
Percent of savings target achieved																				140.00%	122.00%
Energy optimization incentive requested for exceeding savings targets				18,000,000	18,000,000
Requested recovery																			17,000,000
Authorized recovery, collection period																			4 months								10 years	5 years
Authorized Recovery																						14,000,000
Authorized sale of securitized bonds				389,000,000	389,000,000
Number of units planned to be retired				10	10																		7	7	3	3
Number of former MGPs																											23
Power generation of cancelled plant																								830
Proceeds from government grant	69,000,000				69,000,000																										69,000,000
Litigation settlement, gross																														120,000,000
Approved refund of spent nuclear fuel costs																													23,000,000
Annual rate increase requested											145,000,000	148,000,000
Rate of return on equity requested												10.50%
Annual rate increase authorized									89,000,000
Rate of return on equity authorized									10.30%
Annual rate increase self-implemented										110,000,000
PSCR Cost of Power Sold													1,900,000,000	1,800,000,000
Over recovery authorized by the MPSC															8,000,000			2,000,000
Cost of gas sold	$ 1,228,000,000	$ 1,150,000,000	$ 1,512,000,000		$ 1,187,000,000	$ 1,110,000,000	$ 1,438,000,000									$ 900,000,000	$ 900,000,000