Consolidated Statements Of Income - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Operating Revenue $ 1,587 $ 1,486 $ 4,759 $ 4,947
Operating Expenses        
Fuel for electric generation 145 161 367 462
Purchased and interchange power 454 392 1,165 1,082
Purchased power - related parties 22 21 65 61
Cost of gas sold 45 52 490 754
Maintenance and other operating expenses 290 311 859 906
Depreciation and amortization 183 173 597 564
General taxes 62 59 209 200
Total operating expenses 1,201 1,169 3,752 4,029
Operating Income 386 317 1,007 918
Other Income (Expense)        
Interest income 1 1 4 3
Allowance for equity funds used during construction 3 3 9 7
Income from equity method investees 5 4 12 9
Other income 2 2 7 8
Other expense (6) (3) (13) (11)
Total other income 5 7 19 16
Interest Charges        
Interest on long-term debt 103 95 306 288
Other interest expense 8 7 22 20
Allowance for borrowed funds used during construction (1) (1) (4) (3)
Total interest charges 110 101 324 305
Income Before Income Taxes 281 223 702 629
Income Tax Expense 95 75 227 211
Net Income 186 148 475 418
Income Attributable to Noncontrolling Interests     1 1
Net Income Available to Common Stockholders $ 186 $ 148 $ 474 $ 417
Basic Earnings Per Average Common Share $ 0.67 $ 0.53 $ 1.71 $ 1.51
Diluted Earnings Per Average Common Share 0.67 0.53 1.70 1.51
Dividends Declared Per Common Share $ 0.31 $ 0.29 $ 0.93 $ 0.87
Consumers Energy Company [Member]        
Operating Revenue $ 1,498 $ 1,417 $ 4,514 $ 4,726
Operating Expenses        
Fuel for electric generation 118 138 290 381
Purchased and interchange power 445 389 1,148 1,072
Purchased power - related parties 23 21 66 61
Cost of gas sold 39 46 477 737
Maintenance and other operating expenses 265 289 788 845
Depreciation and amortization 182 172 592 560
General taxes 61 57 207 194
Total operating expenses 1,133 1,112 3,568 3,850
Operating Income 365 305 946 876
Other Income (Expense)        
Interest income 1 1 3 3
Interest and dividend income - related parties     1  
Allowance for equity funds used during construction 3 3 9 7
Other income 2 2 7 17
Other expense (6) (3) (13) (11)
Total other income   3 7 16
Interest Charges        
Interest on long-term debt 65 62 195 188
Other interest expense 3 4 9 11
Allowance for borrowed funds used during construction (1) (1) (4) (3)
Total interest charges 67 65 200 196
Income Before Income Taxes 298 243 753 696
Income Tax Expense 103 83 254 237
Net Income 195 160 499 459
Preferred Stock Dividends     1 1
Net Income Available to Common Stockholders $ 195 $ 160 $ 498 $ 458