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New Accounting Standards (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2016
Dec. 31, 2014
Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]      
Unamortized debt issuance costs $ 45   $ 41
Cumulative effect of change in accounting principle 33    
Debt retirement premium payments 18 $ 36  
New Accounting Pronouncement, Early Adoption, Effect [Member]      
New Accounting Pronouncements or Change in Accounting Principle [Line Items]      
Excess tax benefit related to stock 7    
Debt retirement premium payments   36  
Retained Earnings (Accumulated Deficit) [Member]      
New Accounting Pronouncements or Change in Accounting Principle [Line Items]      
Cumulative effect of change in accounting principle 33    
CMS Energy [Member]      
New Accounting Pronouncements or Change in Accounting Principle [Line Items]      
Debt retirement premium payments 18 20  
Consumers Energy Company [Member]      
New Accounting Pronouncements or Change in Accounting Principle [Line Items]      
Unamortized debt issuance costs 25   $ 23
Debt retirement premium payments   16  
Consumers Energy Company [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member]      
New Accounting Pronouncements or Change in Accounting Principle [Line Items]      
Excess tax benefit related to stock $ 7    
Debt retirement premium payments   $ 16