Carrying amount as of the balance sheet date of obligations due all related parties. For classified balance sheets, represents the current portion of such liabilities (due within one year or within the normal operating cycle if longer).

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Balance held at close of period in number of shares.

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Related Party Transactions - Consumers (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			9 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Nov. 30, 2014
Related Party Transaction [Line Items]
Purchased power - related parties	$ 90cms_PurchasedPowerRelatedParties	$ 90cms_PurchasedPowerRelatedParties	$ 87cms_PurchasedPowerRelatedParties
Accounts payable - related parties	10us-gaap_DueToRelatedPartiesCurrent	10us-gaap_DueToRelatedPartiesCurrent
Consumers Energy Company [Member]
Related Party Transaction [Line Items]
Purchased power - related parties	89	89	86
Accounts payable - related parties	12	13
Investment Owned, Balance, Shares	1.1
Investments	38	29
Future purchase power, related parties				3
Consumers Energy Company [Member] \| Credit Agreement [Member]
Related Party Transaction [Line Items]
Maximum borrowing capacity					300
Amount outstanding	$ 0