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Consolidated Statements Of Changes In Equity - USD ($) $ in Millions | Consumers Energy Company [Member] CMS Energy Common Stock [Member] | Consumers Energy Company [Member] Other Paid-in Capital [Member] | Consumers Energy Company [Member] Accumulated Other Comprehensive Income (Loss) [Member] | Consumers Energy Company [Member] Retirement Benefits Liability [Member] | Consumers Energy Company [Member] Investments [Member] | Consumers Energy Company [Member] Retained Earnings (Accumulated Deficit) [Member] | Consumers Energy Company [Member] Preferred Stock [Member] | Consumers Energy Company [Member] | CMS Energy Common Stock [Member] | Other Paid-in Capital [Member] | Accumulated Other Comprehensive Income (Loss) [Member] | Retirement Benefits Liability [Member] | Investments [Member] | Derivative Instruments [Member] | Retained Earnings (Accumulated Deficit) [Member] | Noncontrolling Interest [Member] | Total
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Total Equity, beginning at Dec. 31, 2013 | $ 841 | $ 3,257 | $ (2) | $ (17) | $ 15 | $ 724 | $ 37 | $ 4,857 | $ 3 | $ 4,715 | $ (22) | $ (21) |  | $ (1) | $ (1,242) | $ 37 | $ 3,491
Beginning of period, shares at Dec. 31, 2013 |  |  |  |  |  |  |  |  | 266,137,000 |  |  |  |  |  |  |  |
Common stock issued |  |  |  |  |  |  |  |  |  | 59 |  |  |  |  |  |  |
Number of Shares Issued |  |  |  |  |  |  |  |  | 9,371,000 |  |  |  |  |  |  |  |
Common stock repurchased |  |  |  |  |  |  |  |  |  | (7) |  |  |  |  |  |  |
Common stock repurchased, shares |  |  |  |  |  |  |  |  | (271,000) |  |  |  |  |  |  |  |
Common stock reissued |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock reissued, shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Conversion option on convertible debt |  |  |  |  |  |  |  |  |  | 7 |  |  |  |  |  |  |
Common stock reacquired, value |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock reacquired, shares |  |  |  |  |  |  |  |  | (53,000) |  |  |  |  |  |  |  |
Stockholder contribution |  | 495 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Return of stockholder contribution |  | (178) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net gain arising during the period |  |  |  | (11) |  |  |  | (11) |  |  |  | (29) |  |  |  |  | (29)
Amortization of net actuarial loss, net of tax |  |  |  | 2 |  |  |  | 2 |  |  |  | 3 |  |  |  |  | 3
Amortization of prior service credit |  |  |  |  |  |  |  |  |  |  |  | (1) |  |  |  |  | (1)
Unrealized gain (loss) on investments, net of tax |  |  |  |  | 4 |  |  | 4 |  |  |  |  | (1) |  |  |  | (1)
Reclassification adjustments included in net income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reclassification adjustments included in net income |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 |  |  | (1)
Net income attributable to CMS Energy |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 477 |  | 477
Net income |  |  |  |  |  | 567 |  | 567 |  |  |  |  |  |  |  |  | 479
Dividends declared on common stock |  |  |  |  |  | (457) |  |  |  |  |  |  |  |  | (293) |  |
Dividends declared on preferred stock |  |  |  |  |  | (2) |  |  |  |  |  |  |  |  |  |  |
Income Attributable to Noncontrolling Interests |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 | 2
Distributions, and other changes in noncontrolling interests |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (2) |
End of period, shares at Dec. 31, 2014 |  |  |  |  |  |  |  |  | 275,184,000 |  |  |  |  |  |  |  |
Total Equity, end at Dec. 31, 2014 | 841 | 3,574 | (7) | (26) | 19 | 832 | 37 | 5,277 | $ 3 | 4,774 | (49) | (48) | (1) |  | (1,058) | 37 | 3,707
Common stock issued |  |  |  |  |  |  |  |  |  | 65 |  |  |  |  |  |  | $ 30
Number of Shares Issued |  |  |  |  |  |  |  |  | 2,062,000 |  |  |  |  |  |  |  | 888,610
Common stock repurchased |  |  |  |  |  |  |  |  |  | (12) |  |  |  |  |  |  |
Common stock repurchased, shares |  |  |  |  |  |  |  |  | (306,000) |  |  |  |  |  |  |  |
Common stock reissued |  |  |  |  |  |  |  |  |  | 10 |  |  |  |  |  |  |
Common stock reissued, shares |  |  |  |  |  |  |  |  | 288,000 |  |  |  |  |  |  |  |
Conversion option on convertible debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock reacquired, value |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock reacquired, shares |  |  |  |  |  |  |  |  | (65,000) |  |  |  |  |  |  |  |
Stockholder contribution |  | 150 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Return of stockholder contribution |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net gain arising during the period |  |  |  | 3 |  |  |  | 3 |  |  |  | 1 |  |  |  |  | $ 1
Amortization of net actuarial loss, net of tax |  |  |  | 4 |  |  |  | 4 |  |  |  | 5 |  |  |  |  | 5
Amortization of prior service credit |  |  |  |  |  |  |  |  |  |  |  | (1) |  |  |  |  | (1)
Unrealized gain (loss) on investments, net of tax |  |  |  |  | (1) |  |  | (1) |  |  |  |  | (3) |  |  |  | (3)
Reclassification adjustments included in net income |  |  |  |  | (5) |  |  | 5 |  |  |  |  |  |  |  |  |
Reclassification adjustments included in net income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net income attributable to CMS Energy |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 523 |  | 523
Net income |  |  |  |  |  | 594 |  | $ 594 |  |  |  |  |  |  |  |  | 525
Dividends declared on common stock |  |  |  |  |  | (474) |  |  |  |  |  |  |  |  | (320) |  |
Dividends declared on preferred stock |  |  |  |  |  | (2) |  |  |  |  |  |  |  |  |  |  |
Income Attributable to Noncontrolling Interests |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 | $ 2
Distributions, and other changes in noncontrolling interests |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (2) |
End of period, shares at Dec. 31, 2015 |  |  |  |  |  |  |  | 84,100,000 | 277,163,000 |  |  |  |  |  |  |  | 277,200,000
Total Equity, end at Dec. 31, 2015 | 841 | 3,724 | (6) | (19) | 13 | 950 | 37 | $ 5,546 | $ 3 | 4,837 | (47) | (43) | (4) |  | (855) | 37 | $ 3,975
Total Equity, beginning at Dec. 31, 2014 | 841 | 3,574 | (7) | (26) | 19 | 832 | 37 | $ 5,277 | $ 3 | 4,774 | (49) | (48) | (1) |  | (1,058) | 37 | 3,707
Beginning of period, shares at Dec. 31, 2014 |  |  |  |  |  |  |  |  | 275,184,000 |  |  |  |  |  |  |  |
Common stock issued |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 90
Number of Shares Issued |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,337,781
End of period, shares at Dec. 31, 2016 |  |  |  |  |  |  |  | 84,100,000 | 279,206,000 |  |  |  |  |  |  |  | 279,200,000
Total Equity, end at Dec. 31, 2016 | 841 | 3,999 | (3) | (21) | 18 | 1,065 | 37 | $ 5,939 | $ 3 | 4,916 | (50) | (50) |  |  | (616) | 37 | $ 4,290
Total Equity, beginning at Dec. 31, 2015 | 841 | 3,724 | (6) | (19) | 13 | 950 | 37 | $ 5,546 | $ 3 | 4,837 | (47) | (43) | (4) |  | (855) | 37 | $ 3,975
Beginning of period, shares at Dec. 31, 2015 |  |  |  |  |  |  |  | 84,100,000 | 277,163,000 |  |  |  |  |  |  |  | 277,200,000
Common stock issued |  |  |  |  |  |  |  |  |  | 90 |  |  |  |  |  |  | $ 60
Number of Shares Issued |  |  |  |  |  |  |  |  | 2,580,000 |  |  |  |  |  |  |  | 1,449,171
Common stock repurchased |  |  |  |  |  |  |  |  |  | (11) |  |  |  |  |  |  |
Common stock repurchased, shares |  |  |  |  |  |  |  |  | (292,000) |  |  |  |  |  |  |  |
Common stock reissued |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock reissued, shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Conversion option on convertible debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock reacquired, value |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock reacquired, shares |  |  |  |  |  |  |  |  | (245,000) |  |  |  |  |  |  |  |
Stockholder contribution |  | 275 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Return of stockholder contribution |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net gain arising during the period |  |  |  | (3) |  |  |  | $ (3) |  |  |  | (8) |  |  |  |  | $ (8)
Amortization of net actuarial loss, net of tax |  |  |  | 1 |  |  |  | 1 |  |  |  | 2 |  |  |  |  | 2
Amortization of prior service credit |  |  |  |  |  |  |  |  |  |  |  | (1) |  |  |  |  | (1)
Unrealized gain (loss) on investments, net of tax |  |  |  |  | 3 |  |  | 3 |  |  |  |  | 1 |  |  |  | 1
Reclassification adjustments included in net income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other-than-temporary impairment included in net income |  |  |  |  | 2 |  |  | 2 |  |  |  |  | 3 |  |  |  | 3
Reclassification adjustments included in net income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net income attributable to CMS Energy |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 551 |  | 551
Net income |  |  |  |  |  | 616 |  | $ 616 |  |  |  |  |  |  |  |  | 553
Dividends declared on common stock |  |  |  |  |  | (499) |  |  |  |  |  |  |  |  | (345) |  |
Dividends declared on preferred stock |  |  |  |  |  | (2) |  |  |  |  |  |  |  |  |  |  |
Income Attributable to Noncontrolling Interests |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 | $ 2
Distributions, and other changes in noncontrolling interests |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (2) |
End of period, shares at Dec. 31, 2016 |  |  |  |  |  |  |  | 84,100,000 | 279,206,000 |  |  |  |  |  |  |  | 279,200,000
Total Equity, end at Dec. 31, 2016 | $ 841 | $ 3,999 | $ (3) | $ (21) | $ 18 | $ 1,065 | $ 37 | $ 5,939 | $ 3 | $ 4,916 | $ (50) | $ (50) |  |  | (616) | $ 37 | $ 4,290
Cumulative effect of change in accounting principle |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 33 |  | $ 33

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