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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, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Property, Plant and Equipment [Line Items] |  |  |
Depreciation expense – plant, property, and equipment | $ 778 | $ 739 | $ 687
Total depreciation and amortization expense | 933 | 881 | 811
Securitized regulatory assets |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Amortization expense | 25 | 25 | 25
Software |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Amortization expense | 127 | 114 | 96
Other intangible assets |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Amortization expense | 3 | 3 | 3
Consumers Energy Company |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Depreciation expense – plant, property, and equipment | 768 | 732 | 680
Total depreciation and amortization expense | 921 | 872 | 803
Consumers Energy Company | Securitized regulatory assets |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Amortization expense | 25 | 25 | 25
Consumers Energy Company | Software |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Amortization expense | 125 | 112 | 95
Consumers Energy Company | Other intangible assets |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Amortization expense | $ 3 | $ 3 | $ 3

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