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Financings And Capitalization (Major Long-Term Debt Transactions) (Details) (USD $) | 12 Months Ended
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Dec. 31, 2013
Debt Issuance [Member] |
Debt Instrument [Line Items] |
Debt issuance, principal | $ 1,000,000,000
Debt Issuance [Member] | CMS Energy [Member] |
Debt Instrument [Line Items] |
Debt issuance, principal | 250,000,000
Debt Issuance [Member] | Consumers Energy Company [Member] |
Debt Instrument [Line Items] |
Debt issuance, principal | 750,000,000
Debt Issuance [Member] | Senior Notes 4.70% Due March 2043 [Member] | CMS Energy [Member] |
Debt Instrument [Line Items] |
Debt issuance, principal | 250,000,000
Interest rate | 4.70%
Debt issuance date | March 2013
Maturity date | March 2043
Debt Issuance [Member] | FMBs 3.95% Due May 2043 [Member] | Consumers Energy Company [Member] |
Debt Instrument [Line Items] |
Debt issuance, principal | 425,000,000
Interest rate | 3.95%
Debt issuance date | May 2013
Maturity date | May 2043
Debt Issuance [Member] | FMBs 3.375% Due August 2023 [Member] | Consumers Energy Company [Member] |
Debt Instrument [Line Items] |
Debt issuance, principal | 325,000,000
Interest rate | 3.375%
Debt issuance date | August 2013
Maturity date | August 2023
Debt Retirements [Member] |
Debt Instrument [Line Items] |
Debt retirement, principal | 675,000,000
Debt Retirements [Member] | CMS Energy [Member] |
Debt Instrument [Line Items] |
Debt retirement, principal | 250,000,000
Debt Retirements [Member] | Consumers Energy Company [Member] |
Debt Instrument [Line Items] |
Debt retirement, principal | 425,000,000
Debt Retirements [Member] | Senior Notes 2.750% Due May 2014 [Member] | CMS Energy [Member] |
Debt Instrument [Line Items] |
Debt retirement, principal | 250,000,000
Interest rate | 2.75%
Debt retirement date | September 2013
Maturity date | May 2014
Debt Retirements [Member] | FMB's 6% Due February 2014 [Member] | Consumers Energy Company [Member] |
Debt Instrument [Line Items] |
Debt retirement, principal | 200,000,000
Interest rate | 6.00%
Debt retirement date | June 2013
Maturity date | February 2014
Debt Retirements [Member] | FMB's 5% Due March 2015 [Member] | Consumers Energy Company [Member] |
Debt Instrument [Line Items] |
Debt retirement, principal | $ 225,000,000
Interest rate | 5.00%
Debt retirement date | June 2013
Maturity date | March 2015

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- Definition Debt Instrument Issuance Date 2 + References No definition available. + Details
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Period Type: | duration

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- Definition Date when the debt instrument was partially or fully repaid, which may be presented in a variety of ways (year, month and year, day, month and year, quarter, etc.). + References No definition available. + Details
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- Definition Maturity date of the debt instrument. + References No definition available. + Details
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Balance Type: | na
Period Type: | duration

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- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400 + Details
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- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Details
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- Definition The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations. + References No definition available. + Details
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