Regulatory Matters (Schedule of PSCR Reconciliation Filings Pending with the MPSC) (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 of Filing	March 2011
Net Over/(Under) Recovery, Including Interest, Requested by Consumers	$ (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