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Leases And Palisades Financing (Narrative) (Details) $ in Millions | 1 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Dec. 31, 2016 USD ($) | Dec. 31, 2016 USD ($) MW | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($)
Consumers Energy Company [Member] |  |  |  |
Leases [Line Items] |  |  |  |
Finance Lease Term |  | 15 years |  |
Coal-Carrying Railcars [Member] | Consumers Energy Company [Member] |  |  |  |
Leases [Line Items] |  |  |  |
Operating leases without extension provisions, remaining term |  | 7 years |  |
Operating leases with extension provisions, remaining term |  | 10 years |  |
Gas Transportation Pipeline into Karn [Member] | Consumers Energy Company [Member] |  |  |  |
Leases [Line Items] |  |  |  |
Capital Lease Term |  | 15 years |  |
Capital Lease Remaining Term |  | 5 years |  |
Gas Transportation Pipeline into Zeeland [Member] | Consumers Energy Company [Member] |  |  |  |
Leases [Line Items] |  |  |  |
Capital Lease Term |  | 5 years |  |
Capital lease renewal term |  | 5 years |  |
Capital Lease Remaining Term |  | 1 year |  |
Minimum [Member] | Coal-Carrying Railcars [Member] | Consumers Energy Company [Member] |  |  |  |
Leases [Line Items] |  |  |  |
Operating leases, term |  | 1 year |  |
Minimum [Member] | Long-term PPAs [Member] | Consumers Energy Company [Member] |  |  |  |
Leases [Line Items] |  |  |  |
Lease term |  | 1 year |  |
Maximum [Member] | Coal-Carrying Railcars [Member] | Consumers Energy Company [Member] |  |  |  |
Leases [Line Items] |  |  |  |
Operating leases, term |  | 15 years |  |
Maximum [Member] | Vehicle Fleet Operations [Member] | Consumers Energy Company [Member] |  |  |  |
Leases [Line Items] |  |  |  |
Capital Lease Term |  | 120 months |  |
Maximum [Member] | Long-term PPAs [Member] | Consumers Energy Company [Member] |  |  |  |
Leases [Line Items] |  |  |  |
Lease term |  | 16 years |  |
Financing Leases [Member] |  |  |  |
Leases [Line Items] |  |  |  |
Finance Leases Lessee Balance Sheet Assets Amortization And Interest Charges | $ | $ 17 | $ 17 | $ 18 | $ 19
Financing Leases [Member] | Consumers Energy Company [Member] |  |  |  |
Leases [Line Items] |  |  |  |
Lease termination cost | $ | $ 172 |  |  |
Palisades PPA [Member] |  |  |  |
Leases [Line Items] |  |  |  |
Unrecorded Unconditional Purchase Obligations, Maximum Quantity | MW |  | 798 |  |
Palisades PPA [Member] | Consumers Energy Company [Member] |  |  |  |
Leases [Line Items] |  |  |  |
Unrecorded Unconditional Purchase Obligations, Maximum Quantity | MW |  | 798 |  |

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