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Plant, Property, and Equipment (Schedule Of Plant, Property, and Equipment) (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Plant, property, and equipment, gross | $ 24,400 | $ 22,506 | $ 21,010
Construction work in progress | 763 | 765 |
Accumulated depreciation and amortization | (7,037) | (6,510) |
Total plant, property, and equipment | 18,126 | 16,761 |
Consumers Energy Company |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Plant, property, and equipment, gross | 23,963 | 22,318 | $ 20,838
Construction work in progress | 756 | 753 |
Accumulated depreciation and amortization | (6,958) | (6,441) |
Total plant, property, and equipment | 17,761 | 16,630 |
Plant additions | 1,800 | 1,700 |
Plant retirements | $ 190 | 214 |
Consumers Energy Company | Minimum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, consumers | 3 years |  |
Consumers Energy Company | Maximum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, consumers | 125 years |  |
Independent power production |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Plant, property, and equipment, gross | $ 410 | 163 |
Independent power production | Minimum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, other | 3 years |  |
Independent power production | Maximum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, other | 35 years |  |
Other |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Plant, property, and equipment, gross | $ 2 | 4 |
Other | Minimum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, other | 3 years |  |
Other | Maximum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, other | 5 years |  |
Other non‑utility property |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Other | $ 25 | 21 |
Other non‑utility property | Minimum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, other | 1 year |  |
Other non‑utility property | Maximum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, other | 7 years |  |
Other non‑utility property | Consumers Energy Company |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Other | $ 17 | 17 |
Other non‑utility property | Consumers Energy Company | Minimum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, other | 3 years |  |
Other non‑utility property | Consumers Energy Company | Maximum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, other | 51 years |  |
Generation | Consumers Energy Company |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Generation | $ 6,305 | 6,025 |
Generation | Consumers Energy Company | Minimum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, generation | 22 years |  |
Generation | Consumers Energy Company | Maximum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, generation | 125 years |  |
Distribution | Consumers Energy Company |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Distribution | $ 7,957 | 7,603 |
Distribution | Consumers Energy Company | Minimum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, distribution | 20 years |  |
Distribution | Consumers Energy Company | Maximum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, distribution | 75 years |  |
Transmission | Consumers Energy Company |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Transmission | $ 154 | 66 |
Transmission | Consumers Energy Company | Minimum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, transmission | 46 years |  |
Transmission | Consumers Energy Company | Maximum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, transmission | 75 years |  |
Other | Consumers Energy Company |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Other | $ 1,316 | 1,229 |
Other | Consumers Energy Company | Minimum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, other | 5 years |  |
Other | Consumers Energy Company | Maximum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, other | 50 years |  |
Assets under capital leases and financing obligation | Consumers Energy Company |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Capital leases and financing obligation | $ 295 | 298 |
Distribution | Consumers Energy Company |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Distribution | $ 4,651 | 4,182 |
Distribution | Consumers Energy Company | Minimum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, distribution | 20 years |  |
Distribution | Consumers Energy Company | Maximum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, distribution | 85 years |  |
Transmission | Consumers Energy Company |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Transmission | $ 1,521 | 1,278 |
Transmission | Consumers Energy Company | Minimum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, transmission | 17 years |  |
Transmission | Consumers Energy Company | Maximum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, transmission | 75 years |  |
Underground Storage Facilities | Consumers Energy Company |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Other | $ 910 | 842 |
Underground Storage Facilities | Consumers Energy Company | Minimum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, other | 27 years |  |
Underground Storage Facilities | Consumers Energy Company | Maximum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, other | 75 years |  |
Other | Consumers Energy Company |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Other | $ 823 | 764 |
Other | Consumers Energy Company | Minimum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, other | 5 years |  |
Other | Consumers Energy Company | Maximum |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Estimated depreciable life in years, other | 50 years |  |
Capital Leases | Consumers Energy Company |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Capital leases and financing obligation | $ 14 | 14 |
Natural Gas | Underground Storage Facilities | Consumers Energy Company |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Other | $ 26 | $ 26 |

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