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Earnings Per Share - CMS Energy (Basic And Diluted EPS Computations) (Details) (USD $)
In Millions, except Per Share data, unless otherwise specified |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
|
Sep. 30, 2013
|
Sep. 30, 2012
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Sep. 30, 2013
|
Sep. 30, 2012
|
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| Earnings Per Share - CMS Energy [Abstract] | ||||
| Income From continuing operations | $ 127 | $ 149 | $ 352 | $ 310 |
| Income attributable to noncontrolling interests | 1 | 1 | 2 | 2 |
| Income from Continuing operations available to common stockholders basic and diluted | $ 126 | $ 148 | $ 350 | $ 308 |
| Weighted average shares - basic | 264.8 | 262.9 | 264.3 | 259.9 |
| Add dilutive contingently convertible securities | 6.2 | 5.1 | 6.2 | 7.2 |
| Add dilutive non-vested awards | 1.0 | 1.0 | 1.1 | 1.0 |
| Weighted average shares - diluted | 272.0 | 269.0 | 271.6 | 268.1 |
| Basic | $ 0.48 | $ 0.56 | $ 1.32 | $ 1.18 |
| Diluted | $ 0.46 | $ 0.55 | $ 1.29 | $ 1.14 |