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Leases (Narrative) (Details) (Consumers Energy Company [Member]) | 12 Months Ended
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Dec. 31, 2012
Coal-Carrying Railcars [Member] |
Operating Leases Without Extension Provisions Expiration Time Period Remaining | 11 years
Operating Leases With Extension Provisions Expiration Time Period Remaining | 14 years
Vehicle Fleet Operations [Member] |
Capital Lease Term | 120 months
Gas Transportation Pipeline into Karn [Member] |
Capital Lease Term | 15 years
Capital Lease Remaining Term | 9 years
Gas Transportation Pipeline into Zeeland [Member] |
Capital Lease Term | 12 years
Capital Lease Remaining Term | 5 years
Capital lease renewal term | 5 years
Minimum [Member] | Long-term PPAs [Member] |
Capital Lease Term | 1 year
Maximum [Member] | Long-term PPAs [Member] |
Capital Lease Term | 20 years

X
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X
- Definition Capital lease renewal term + References No definition available. + Details
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- Definition Term of capital lease contract. + References No definition available. + Details
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X
- Definition Time period remaining over which operating leases are expiring with extension provisions in the contracts. + References No definition available. + Details
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