Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash Flows from Operating Activities
Net income	$ 479us-gaap_ProfitLoss	$ 454us-gaap_ProfitLoss	$ 384us-gaap_ProfitLoss
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	685	628	598
Deferred income taxes and investment tax credit	227	268	227
Postretirement benefits expense	23	144	187
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Postretirement benefits contributions	(32)	(229)	(72)
Proceeds from government grant		69cms_ProceedsFromGovernmentGrant
Cash provided by (used in) changes in assets and liabilities
Decrease (increase) in accounts receivable, notes receivable, and accrued revenue	(31)	(120)	(147)
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Increase (decrease) in accounts payable	50	4	(35)
Other current and non-current assets and liabilities	(15)	(88)	(78)
Net cash provided by operating activities	1,447	1,421	1,241
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(1,577)	(1,325)	(1,227)
Cost to retire property	(75)	(56)	(49)
Increase in EnerBank notes receivable	(255)	(139)	(63)
Other investing activities	(3)	(12)	(11)
Net cash used in investing activities	(1,910)	(1,532)	(1,350)
Cash Flows from Financing Activities
Proceeds from issuance of long-term debt	1,428	1,025	1,650
Proceeds from EnerBank notes, net	233	125	65
Issuance of common stock	43	36	30
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Payment of capital lease obligations and other financing costs	(51)	(42)	(35)
Increase (decrease) in notes payable	(110)	60	110
Net cash provided by (used in) financing activities	498	190	41
Net Increase (Decrease) in Cash and Cash Equivalents	35	79	(68)
Cash and Cash Equivalents, Beginning of Period	172	93	161
Cash and Cash Equivalents, End of Period	207	172	93
Cash transactions
Interest paid (net of amounts capitalized)	380us-gaap_InterestPaidNet	382us-gaap_InterestPaidNet	377us-gaap_InterestPaidNet
Income taxes paid	22us-gaap_IncomeTaxesPaidNet	34us-gaap_IncomeTaxesPaidNet	19us-gaap_IncomeTaxesPaidNet
Non-Cash Transactions
Capital expenditures not paid	201	176	110
Other assets placed under capital lease	7us-gaap_CapitalLeaseObligationsIncurred	6us-gaap_CapitalLeaseObligationsIncurred	9us-gaap_CapitalLeaseObligationsIncurred
Consumers Energy Company [Member]
Cash Flows from Operating Activities
Net income	567	534	439
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	678	622	592
Deferred income taxes and investment tax credit	263	164	150
Postretirement benefits expense	24	142	184
Bad debt expense	72	63	53
Other non-cash operating activities	10	12	14
Postretirement benefits contributions	(29)	(222)	(68)
Proceeds from government grant		69
Cash provided by (used in) changes in assets and liabilities
Decrease (increase) in accounts receivable, notes receivable, and accrued revenue	(16)	(116)	(145)
Decrease (increase) in inventories	(36)	205	107
Increase (decrease) in accounts payable	47	12	(23)
Other current and non-current assets and liabilities	(242)	(134)	50
Net cash provided by operating activities	1,338	1,351	1,353
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(1,573)	(1,320)	(1,222)
Cost to retire property	(75)	(56)	(49)
Other investing activities	(5)	(11)	(8)
Net cash used in investing activities	(1,653)	(1,387)	(1,279)
Cash Flows from Financing Activities
Proceeds from issuance of long-term debt	878	750	1,075
Retirement of long-term debt	(220)	(466)	(1,064)
Payment of common and preferred stock dividends	(459)	(408)	(395)
Stockholder contribution	495	150	150
Return of stockholder contribution	(178)
Payment of capital lease obligations and other financing costs	(38)	(37)	(30)
Increase (decrease) in notes payable	(110)	60	110
Net cash provided by (used in) financing activities	368	49	(154)
Net Increase (Decrease) in Cash and Cash Equivalents	53	13	(80)
Cash and Cash Equivalents, Beginning of Period	18	5	85
Cash and Cash Equivalents, End of Period	71	18	5
Cash transactions
Interest paid (net of amounts capitalized)	233	236	224
Income taxes paid	266	225	63
Non-Cash Transactions
Capital expenditures not paid	201	176	110
Other assets placed under capital lease	$ 7	$ 6	$ 9

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- Definition

The cash inflow associated with the amount received by a corporation from a shareholder during the period.

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The cash inflow from the additional capital contribution to the entity.

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The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

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The net cash inflow or outflow from other financing activities. This element is used when there is not a more specific and appropriate element in the taxonomy.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Amount of cash inflow (outflow) from long-term debt supported by a written promise to pay an obligation.

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The net cash inflow or outflow for borrowing having initial term of repayment within one year or the normal operating cycle, if longer.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

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