Regulatory Matters (Schedule of Power Supply Cost Recovery Reconciliations) (Details) (Power Supply Cost Recover (PSCR) [Member], Consumers Energy Company [Member], USD $) In Millions	12 Months Ended
Dec. 31, 2010
Power Supply Cost Recover (PSCR) [Member] \| Consumers Energy Company [Member]
Date Filed	March 2011
Net Over (Under) Recovery Of Expense Including Interest	$ (15)
PSCR Cost of Power Sold	$ 1,700.0

Total costs related to electricity produced and sold during the reporting period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 5
-Section 03
-Paragraph 2

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2(b))
-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Name:	us-gaap_CostOfGoodsSoldElectric
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration