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Plant, Property, and Equipment (Schedule Of Depreciation And Amortization Expense) (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Property, Plant and Equipment [Line Items] |  |  |
Depreciation expense - plant, property, and equipment | $ 591 | $ 551 | $ 516
Total depreciation and amortization expense | 750 | 685 | 628
Securitized Regulatory Assets [Member] |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Amortization expense | 83 | 75 | 63
Other Regulatory Assets [Member] |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Amortization expense | 2 | 5 | 6
Software [Member] |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Amortization expense | 70 | 50 | 40
Other Intangible Assets [Member] |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Amortization expense | 4 | 4 | 3
Consumers Energy Company [Member] |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Depreciation expense - plant, property, and equipment | 586 | 546 | 511
Total depreciation and amortization expense | 744 | 678 | 622
Consumers Energy Company [Member] | Securitized Regulatory Assets [Member] |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Amortization expense | 83 | 75 | 63
Consumers Energy Company [Member] | Other Regulatory Assets [Member] |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Amortization expense | 2 | 5 | 6
Consumers Energy Company [Member] | Software [Member] |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Amortization expense | 69 | 49 | 39
Consumers Energy Company [Member] | Other Intangible Assets [Member] |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Amortization expense | $ 4 | $ 3 | $ 3

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- Definition The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585 + Details
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- Definition The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585 + Details
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- Definition The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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