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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, 2012
|
Sep. 30, 2011
|
Sep. 30, 2012
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Sep. 30, 2011
|
|
| Earnings Per Share - CMS Energy [Abstract] | ||||
| Income from continuing operations | $ 149 | $ 140 | $ 310 | $ 374 |
| Less income attributable to noncontrolling interest | 1 | 1 | 2 | 2 |
| Income from Continuing Operations Available to Common Stockholders - Basic and Diluted | $ 148 | $ 139 | $ 308 | $ 372 |
| Weighted average shares - basic | 262.9 | 251.3 | 259.9 | 250.5 |
| Add dilutive contingently convertible securities | 5.1 | 11.3 | 7.2 | 11.4 |
| Add dilutive non-vested awards and options | 1.0 | 0.6 | 1.0 | 0.4 |
| Add dilutive convertible debentures | 0.7 | |||
| Weighted average shares - diluted | 269.0 | 263.9 | 268.1 | 262.3 |
| Basic | $ 0.56 | $ 0.55 | $ 1.18 | $ 1.48 |
| Diluted | $ 0.55 | $ 0.53 | $ 1.14 | $ 1.42 |