XML 57 R125.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Related Party Transactions - Consumers (Details) - USD ($)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Jan. 31, 2019
Consumers Energy Company        
Related Party Transaction [Line Items]        
Purchased power – related parties $ 75,000,000 $ 83,000,000 $ 90,000,000  
Due to related parties 26,000,000 20,000,000    
Accounts receivable - related parties 8,000,000 13,000,000    
Investments 1,000,000 1,000,000    
Consumers Energy Company | Credit Agreement        
Related Party Transaction [Line Items]        
Maximum borrowing capacity       $ 300,000,000
Amount outstanding $ 0      
CMS Energy Note Payable        
Related Party Transaction [Line Items]        
Notes payable   $ 146,000,000    
Natural Gas Transportation Agreement | CMS Energy Subsidiary | Consumers Energy Company        
Related Party Transaction [Line Items]        
Direct financing lease term 20 years