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Leases And Palisades Financing (Schedule of Rent Expense) (Details) - Consumers Energy Company - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Leases [Line Items]      
Contingent rental expense $ 101 $ 96 $ 82
PPAs      
Leases [Line Items]      
Minimum operating lease expense 4 5 6
Other agreements      
Leases [Line Items]      
Minimum operating lease expense $ 11 $ 15 $ 14