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Regulatory Matters (Schedule Of The Components Of Regulatory Assets and Liabilities) (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2015 | Dec. 31, 2014
Regulatory Matters [Line Items] |  |  |
Regulatory assets, current |  | $ 16 | $ 89
Regulatory assets, noncurrent |  | 1,840 | 1,956
Regulatory liabilities, current |  | 82 | 67
Regulatory liabilities, noncurrent |  | 2,088 | 2,095
Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Regulatory assets, current |  | 16 | 89
Regulatory assets, noncurrent |  | 1,840 | 1,956
Total regulatory asset |  | 1,856 | 2,045
Regulatory liabilities, current |  | 82 | 67
Regulatory liabilities, noncurrent |  | 2,088 | 2,095
Total regulatory liabilities |  | 2,170 | 2,162
Cost Of Removal [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Regulatory liabilities, noncurrent |  | $ 1,745 | 1,673
Renewable Energy Plan [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Noncurrent Regulatory Liability, Recovery End Date |  | 2028 |
Regulatory liabilities, noncurrent |  | $ 109 | 131
Income Taxes, Net [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Current Regulatory Liability Recovery End Date |  | 2016 |
Regulatory liabilities, current |  | $ 64 | 64
Regulatory liabilities, noncurrent |  | 64 | 103
ARO [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Regulatory liabilities, noncurrent |  | $ 73 | 83
Renewable Energy Grant [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Noncurrent Regulatory Liability, Recovery End Date |  | 2043 |
Regulatory liabilities, noncurrent |  | $ 60 | 63
Energy Optimization Plan [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Regulatory liabilities, noncurrent |  | $ 26 | 32
Other Regulatory Assets [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Current Regulatory Liability Recovery End Date |  | 2016 |
Regulatory liabilities, current |  | $ 4 | 3
Regulatory liabilities, noncurrent |  | 11 | 10
Postretirement Benefits [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Regulatory assets, noncurrent | [1] | $ 1,096 | 1,195
Securitized Costs [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Regulatory Current Asset, End Date for Recovery | [2] | 2015 |
Current Regulatory Liability Recovery End Date |  | 2016 |
Regulatory assets, current | [2] |  | 61
Regulatory liabilities, current |  | $ 14 |
Costs Of Electric Generating Units To Be Retired And Securitized [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Noncurrent Regulatory Asset Recovery End Date | [2] | 2029 |
Regulatory assets, noncurrent | [2] | $ 348 | 370
Manufactured Gas Plant [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Regulatory assets, noncurrent | [3] | 146 | 147
ARO [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Regulatory assets, noncurrent | [3] | 151 | 139
Unamortized Debt Costs [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Regulatory assets, noncurrent | [3] | 61 | 66
Gas Storage Inventory Adjustments [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Regulatory assets, noncurrent | [3] | $ 18 | 21
Energy Optimization Plan Incentive [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Regulatory Current Asset, End Date for Recovery | [4] | 2016 |
Noncurrent Regulatory Asset Recovery End Date | [3],[4] | 2017 |
Regulatory assets, current | [4] | $ 16 | 17
Regulatory assets, noncurrent | [3],[4] | $ 18 | 17
Major Maintenance [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Regulatory Current Asset, End Date for Recovery | [2] | 2015 |
Regulatory assets, current | [2] |  | 8
Other Regulatory Assets [Member] | Consumers Energy Company [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Regulatory Current Asset, End Date for Recovery | [2] | 2015 |
Regulatory assets, current | [2] |  | 3
Regulatory assets, noncurrent |  | $ 2 | $ 1
[1] | This regulatory asset is offset partially by liabilities. The net amount is included in rate base, thereby providing a return.
[2] | These regulatory assets are included in rate base (or are expected to be included, for costs incurred subsequent to the most recently approved rate case), thereby providing a return on expenditures, or provide a specific return on investment authorized by the MPSC.
[3] | These regulatory assets represent incurred costs for which the MPSC has provided, or Consumers expects, recovery without a return on investment.
[4] | These regulatory assets have arisen from alternative revenue programs and are not associated with incurred costs or capital investments. Therefore, the MPSC has provided for recovery without a return.

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- Definition The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
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- Definition Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
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