Consolidated Statements Of Changes In Equity - USD ($)
shares in Millions, $ in Millions
Consumers Energy Company [Member]
CMS Energy Common Stock [Member]
Consumers Energy Company [Member]
Other Paid-in Capital [Member]
Consumers Energy Company [Member]
Accumulated Other Comprehensive Income (Loss) [Member]
Consumers Energy Company [Member]
Retirement Benefits Liability [Member]
Consumers Energy Company [Member]
Investments [Member]
Consumers Energy Company [Member]
Retained Earnings (Accumulated Deficit) [Member]
Consumers Energy Company [Member]
Preferred Stock [Member]
Consumers Energy Company [Member]
CMS Energy Common Stock [Member]
Other Paid-in Capital [Member]
Accumulated Other Comprehensive Income (Loss) [Member]
Retirement Benefits Liability [Member]
Investments [Member]
Retained Earnings (Accumulated Deficit) [Member]
Noncontrolling Interest [Member]
Total
Total Equity, beginning at Dec. 31, 2014 $ 841 $ 3,574 $ (7) $ (26) $ 19 $ 832 $ 37 $ 5,277 $ 3 $ 4,774 $ (49) $ (48) $ (1) $ (1,058) $ 37 $ 3,707
Common stock issued                   56            
Common stock repurchased                   (11)            
Common stock reissued                   10            
Stockholder contribution   150                            
Amortization of net actuarial loss       3       3       4       4
Amortization of prior service credit                       (1)       (1)
Unrealized gain (loss) on investments         (2)     (2)         (3)     (3)
Reclassification adjustments included in net income         (5)     5                
Net income attributable to CMS Energy                               417
Net income           459   459           417   418
Dividends declared on common stock           (359)               (240)    
Dividends declared on preferred stock           (1)                    
Income Attributable to Noncontrolling Interests                             1 1
Distributions, and other changes in noncontrolling interests                             (1)  
Total Equity, end at Sep. 30, 2015 841 3,724 (11) (23) 12 931 37 5,522 3 4,829 (49) (45) (4) (881)   3,939
Total Equity, beginning at Jun. 30, 2015 841 3,724 (12) (24) 12 876 37 5,466 3 4,812 (48) (46) (2) (949) 37 3,855
Common stock issued                   17            
Common stock repurchased                              
Stockholder contribution                              
Amortization of net actuarial loss       1       1       2       2
Amortization of prior service credit                       (1)       (1)
Unrealized gain (loss) on investments                         (2)     (2)
Reclassification adjustments included in net income                              
Net income attributable to CMS Energy                               148
Net income           160   160           148   148
Dividends declared on common stock           (105)               (80)    
Total Equity, end at Sep. 30, 2015 841 3,724 (11) (23) 12 931 37 5,522 3 4,829 (49) (45) (4) (881)   3,939
Total Equity, beginning at Dec. 31, 2015 841 3,724 (6) (19) 13 950 37 $ 5,546 3 4,837 (47) (43) (4) (855) 37 $ 3,975
Beginning of period, shares at Dec. 31, 2015               84.1               277.2
Common stock issued                   82            
Common stock repurchased                   (11)            
Stockholder contribution   275                            
Amortization of net actuarial loss                     2       $ 2
Amortization of prior service credit                       (1)       (1)
Unrealized gain (loss) on investments         3     $ 3         1     1
Reclassification adjustments included in net income                              
Net income attributable to CMS Energy                               474
Net income           499   $ 499           474   475
Dividends declared on common stock           (361)               (259)    
Dividends declared on preferred stock           (1)                    
Income Attributable to Noncontrolling Interests                             1 $ 1
Distributions, and other changes in noncontrolling interests                             (1)  
End of period, shares at Sep. 30, 2016               84.1               279.1
Total Equity, end at Sep. 30, 2016 841 3,999 (3) (19) 16 1,087 37 $ 5,961 3 4,908 (45) (42) (3) (607)   $ 4,296
Total Equity, beginning at Jun. 30, 2016 841 3,999 (1) (19) 18 1,040 37 5,916 3 4,906 (47) (43) (4) (706) $ 37 4,193
Common stock issued                   3            
Common stock repurchased                   (1)            
Stockholder contribution                              
Amortization of net actuarial loss                     1       1
Unrealized gain (loss) on investments         (2)     (2)         1     1
Reclassification adjustments included in net income                              
Net income attributable to CMS Energy                               186
Net income           195   $ 195           186   $ 186
Dividends declared on common stock           (148)               (87)    
End of period, shares at Sep. 30, 2016               84.1               279.1
Total Equity, end at Sep. 30, 2016 $ 841 $ 3,999 $ (3) $ (19) $ 16 $ 1,087 $ 37 $ 5,961 $ 3 $ 4,908 $ (45) $ (42) $ (3) (607)   $ 4,296
Cumulative effect of change in accounting principle                           $ 33