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Financings and Capitalization (Narrative) (Details) (USD $)
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9 Months Ended | 9 Months Ended | 23 Months Ended | ||||
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Sep. 30, 2013
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Sep. 30, 2013
CMS Energy [Member]
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Sep. 30, 2013
Consumers Energy Company [Member]
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May 31, 2013
Consumers Energy Company [Member]
$4.16 Series [Member]
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Sep. 30, 2013
Short-Term Borrowings [Member]
Consumers Energy Company [Member]
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Apr. 25, 2013
Continuous Equity Program [Member]
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Sep. 30, 2013
Senior Notes 5.5% Due June 2029 [Member]
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| Financing And Capitalization [Line Items] | |||||||
| Amount of Facility | $ 250,000,000 | ||||||
| Accounts receivable sales facility, current borrowing capacity | 250,000,000 | ||||||
| Average short-term borrowings | 7,000,000 | ||||||
| Weighted average annual interest rate | 0.94% | ||||||
| Number of trading days, adjusted trigger price contingencies were met | 20 days | ||||||
| Number of trading days | 30 days | ||||||
| Limitation on payment of stock dividends | 3,400,000,000 | ||||||
| Unrestricted retained earnings | 650,000,000 | ||||||
| Common stock dividends from Consumers | 300,000,000 | ||||||
| Aggregate sales price of an equity offering program | 50,000,000 | ||||||
| Preferred stock, par value | $ 4.16 | ||||||
| Redemption price per share | $ 103.25 | ||||||
| Redemption price | $ 7,000,000 | ||||||
| Preferred shares outstanding | 68,451 |