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Plant, Property, and Equipment (Schedule Of Plant, Property, and Equipment) (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Plant, property, and equipment, gross |  | $ 21,010 | $ 18,943 | $ 17,721
Construction work in progress |  | 761 | 1,509 |
Less accumulated depreciation and amortization |  | (6,056) | (5,747) |
Total plant, property, and equipment | [1] | 15,715 | 14,705 |
Consumers Energy Company [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Plant, property, and equipment, gross |  | 20,838 | 18,797 | $ 17,580
Construction work in progress |  | 759 | 1,467 |
Less accumulated depreciation and amortization |  | (5,994) | (5,676) |
Total plant, property, and equipment | [1] | 15,603 | 14,588 |
Public Utilities, Property Plant and Equipment Additions |  | 2,300 | 1,400 |
Public Utilities, Property Plant and Equipment Disposals |  | $ 285 | 187 |
Consumers Energy Company [Member] | Minimum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Consumers |  | 5 years |  |
Consumers Energy Company [Member] | Maximum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Consumers |  | 125 years |  |
Electricity Generation Plant, Non-Nuclear [Member] | Consumers Energy Company [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Public Utilities, Property, Plant and Equipment, Generation or Processing |  | $ 5,900 | 4,925 |
Electricity Generation Plant, Non-Nuclear [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Generation |  | 22 years |  |
Electricity Generation Plant, Non-Nuclear [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Generation |  | 125 years |  |
Electric Distribution [Member] | Consumers Energy Company [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Public Utilities, Property, Plant and Equipment, Distribution |  | $ 7,149 | 6,809 |
Electric Distribution [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Distribution |  | 20 years |  |
Electric Distribution [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Distribution |  | 75 years |  |
Electric Transmission [Member] | Consumers Energy Company [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Public Utilities, Property, Plant and Equipment, Transmission |  | $ 59 |  |
Electric Transmission [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Transmission |  | 46 years |  |
Electric Transmission [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Transmission |  | 75 years |  |
Electric Other [Member] | Consumers Energy Company [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment |  | $ 1,137 | 1,039 |
Electric Other [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Other |  | 5 years |  |
Electric Other [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Other |  | 50 years |  |
Electric Capital Leases [Member] | Consumers Energy Company [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Capital leases and financing obligation | [1] | $ 295 | 286 |
Gas Distribution [Member] | Consumers Energy Company [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Public Utilities, Property, Plant and Equipment, Distribution |  | $ 3,806 | 3,497 |
Gas Distribution [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Distribution |  | 28 years |  |
Gas Distribution [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Distribution |  | 80 years |  |
Gas Transmission [Member] | Consumers Energy Company [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Public Utilities, Property, Plant and Equipment, Transmission |  | $ 1,124 | 981 |
Gas Transmission [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Transmission |  | 17 years |  |
Gas Transmission [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Transmission |  | 75 years |  |
Gas Underground Storage Facilities [Member] | Consumers Energy Company [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment | [2] | $ 630 | 601 |
Gas Underground Storage Facilities [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Other | [2] | 29 years |  |
Gas Underground Storage Facilities [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Other | [2] | 65 years |  |
Gas Other [Member] | Consumers Energy Company [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment |  | $ 708 | 630 |
Gas Other [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Other |  | 5 years |  |
Gas Other [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Other |  | 50 years |  |
Gas Capital Leases [Member] | Consumers Energy Company [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Capital leases and financing obligation |  | $ 15 | 14 |
Natural Gas [Member] | Gas Underground Storage Facilities [Member] | Consumers Energy Company [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment |  | 26 | 26 |
Enterprises IPP [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Plant, property, and equipment, gross |  | $ 141 | 95 |
Enterprises IPP [Member] | Minimum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Other |  | 3 years |  |
Enterprises IPP [Member] | Maximum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Other |  | 30 years |  |
Enterprises Other [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Plant, property, and equipment, gross |  | $ 16 | 25 |
Enterprises Other [Member] | Minimum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Other |  | 3 years |  |
Enterprises Other [Member] | Maximum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Other |  | 40 years |  |
Other [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Other non-utility property |  | $ 15 | 26 |
Other [Member] | Minimum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Other |  | 1 year |  |
Other [Member] | Maximum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Other |  | 7 years |  |
Other [Member] | Consumers Energy Company [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Other non-utility property |  | $ 15 | $ 15 |
Other [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Other |  | 8 years |  |
Other [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Depreciable Life in Years, Other |  | 51 years |  |
[1] | For the year ended December 31, 2016, Consumers' plant additions were $2.3 billion and plant retirements were $285 million. For the year ended December 31, 2015, Consumers' plant additions were $1.4 billion and plant retirements were $187 million.
[2] | Underground storage includes base natural gas of $26 million at December 31, 2016 and 2015. Base natural gas is not subject to depreciation.

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