Earnings Per Share - CMS Energy (Basic And Diluted EPS Computations) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
|
| Earnings Per Share - CMS Energy [Abstract] | ||||
| Net income | $ 186 | $ 148 | $ 475 | $ 418 |
| Less income attributable to noncontrolling interest | 1 | 1 | ||
| Net Income Available to Common Stockholders | $ 186 | $ 148 | $ 474 | $ 417 |
| Weighted average shares - basic | 278.2 | 276.0 | 277.7 | 275.4 |
| Add dilutive non-vested stock awards | 1.0 | 0.9 | 1.1 | 0.9 |
| Weighted average shares - diluted | 279.2 | 276.9 | 278.8 | 276.3 |
| Basic | $ 0.67 | $ 0.53 | $ 1.71 | $ 1.51 |
| Diluted | $ 0.67 | $ 0.53 | $ 1.70 | $ 1.51 |