XML 32 R1.htm IDEA: XBRL DOCUMENT v3.3.1.900
Document And Entity Information - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2015
Jan. 13, 2016
Jun. 30, 2015
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2015    
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2015    
Trading Symbol cms    
Entity Registrant Name CMS Energy Corporation    
Entity Central Index Key 0000811156    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Large Accelerated Filer    
Entity Public Float     $ 8,736
CMS Energy [Member]      
Entity Common Stock, Shares Outstanding   277,970,146  
Consumers Energy Company [Member]      
Entity Registrant Name Consumers Energy Company    
Entity Central Index Key 0000201533    
Entity Filer Category Non-accelerated Filer    
Entity Common Stock, Shares Outstanding   84,108,789