Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions |
Sep. 30, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Allowances for doubtful accounts receivable | $ 27 | $ 28 |
| Allowances for doubtful notes receivable | $ 12 | $ 9 |
| Common stock, shares authorized | 350,000,000 | 350,000,000 |
| Common stock, shares outstanding | 279,100,000 | 277,200,000 |
| Consumers Energy Company [Member] | ||
| Allowances for doubtful accounts receivable | $ 27 | $ 28 |
| Common stock, shares authorized | 125,000,000 | 125,000,000 |
| Common stock, shares outstanding | 84,100,000 | 84,100,000 |