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Plant, Property, and Equipment (Jointly Owned Regulated Utility Facilities) (Details) - Consumers Energy Company
$ in Millions
Dec. 31, 2019
USD ($)
J.H. Campbell Unit 3  
Public Utility, Property, Plant and Equipment [Line Items]  
Ownership share 93.30%
Utility plant in service $ 1,731
Accumulated depreciation (753)
Construction work in progress 16
Net investment $ 994
Ludington  
Public Utility, Property, Plant and Equipment [Line Items]  
Ownership share 51.00%
Utility plant in service $ 486
Accumulated depreciation (166)
Construction work in progress 64
Net investment 384
Other  
Public Utility, Property, Plant and Equipment [Line Items]  
Utility plant in service 233
Accumulated depreciation (68)
Construction work in progress 15
Net investment $ 180