XML 53 R57.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Regulatory Matters (Schedule of PSCR Reconciliation Filings Pending with the MPSC) (Details) (Power Supply Cost Recover (PSCR) [Member], Consumers Energy Company [Member], USD $) | 12 Months Ended
--- | ---
Dec. 31, 2012 | Dec. 31, 2011
Power Supply Cost Recover (PSCR) [Member] | Consumers Energy Company [Member] |  |
Regulatory Matters [Line Items] |  |
Date of Filing | March 2013 |
Net Over Under Recovery Of Expense Including Interest Requested | $ (18,000,000) |
PSCR Cost of Power Sold | $ 1,900,000,000 | $ 1,800,000,000

X
- Definition Date of Filing + References No definition available. + Details
Name: | cms_DateOfFiling
Namespace Prefix: | cms_
Data Type: | invest:dateStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Net over-/(under-) recovery of expense, including interest, requested by Consumers. + References No definition available. + Details
Name: | cms_NetOverUnderRecoveryOfExpenseIncludingInterestRequested
Namespace Prefix: | cms_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | cms_RegulatoryMattersLineItems
Namespace Prefix: | cms_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Total costs related to electricity produced and sold during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 2 -Article 5 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=26872669&loc=d3e20235-122688 + Details
Name: | us-gaap_CostOfGoodsSoldElectric
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration