Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash Flows from Operating Activities
Net income	$ 382	$ 352
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	503	463
Deferred income taxes and investment tax credit	178	213
Postretirement benefits expense	17	120
Other non-cash operating activities	64	59
Postretirement benefits contributions	(5)	(109)
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	111	134
Decrease (increase) in inventories	(161)	(6)
Increase (decrease) in accounts payable	(14)	(32)
Other current and non-current assets and liabilities	(113)	(145)
Net cash provided by operating activities	962	1,118
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(1,125)	(900)
Cost to retire property	(62)	(38)
Increase in EnerBank loans receivable	(164)	(53)
Other investing activities	4	(13)
Net cash used in investing activities	(1,347)	(1,004)
Cash Flows from Financing Activities
Proceeds from issuance of long-term debt	1,428	1,025
Proceeds from EnerBank notes, net	147	48
Issuance of common stock	40	32
Retirement of long-term debt	(488)	(705)
Payment of common and preferred stock dividends	(220)	(205)
Decrease in notes payable	(170)	(110)
Payment of capital lease obligations and other financing costs	(31)	(32)
Net cash provided by financing activities	706	53
Net Increase (Decrease) in Cash and Cash Equivalents	321	167
Cash and Cash Equivalents, Beginning of Period	172	93
Cash and Cash Equivalents, End of Period	493	260
Consumers Energy Company [Member]
Cash Flows from Operating Activities
Net income	449	415
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	498	459
Deferred income taxes and investment tax credit	64	141
Postretirement benefits expense	18	117
Other non-cash operating activities	54	52
Postretirement benefits contributions	(3)	(106)
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	120	135
Decrease (increase) in inventories	(163)	(5)
Increase (decrease) in accounts payable	(6)	(22)
Other current and non-current assets and liabilities	(83)	(121)
Net cash provided by operating activities	948	1,134
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(1,123)	(895)
Cost to retire property	(62)	(38)
Other investing activities	3	(12)
Net cash used in investing activities	(1,182)	(945)
Cash Flows from Financing Activities
Proceeds from issuance of long-term debt	878	750
Retirement of long-term debt	(208)	(455)
Payment of common and preferred stock dividends	(376)	(302)
Stockholder contribution	317	150
Decrease in notes payable	(170)	(110)
Payment of capital lease obligations and other financing costs	(25)	(28)
Net cash provided by financing activities	416	5
Net Increase (Decrease) in Cash and Cash Equivalents	182	194
Cash and Cash Equivalents, Beginning of Period	18	5
Cash and Cash Equivalents, End of Period	$ 200	$ 199