Consolidated Statements of Cash Flows (USD $) In Millions	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Cash Flows from Operating Activities
Net Income	$ 236	$ 172
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	284	303
Deferred income taxes and investment tax credit	74	107
Postretirement benefits expense	83	88
Other non-cash operating activities	39	41
Postretirement benefits contributions	(39)	(153)
Changes in other assets and liabilities:
Decrease in accounts receivable, notes receivable, and accrued revenue	215	178
Decrease in accrued power supply revenue	15	22
Decrease in inventories	204	230
Increase (decrease) in accounts payable	34	41
Decrease in accrued expenses	(36)	(51)
Decrease in other current and non-current assets	71	88
Increase (decrease) in other current and non-current liabilities	36	(18)
Net cash provided by operating activities	1,216	1,048
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(399)	(424)
Cost to retire property	(28)	(20)
Cash effect of deconsolidation of partnerships	0	(10)
Other investing activities	(44)	(36)
Net cash used in investing activities	(471)	(490)
Cash Flows from Financing Activities
Proceeds from issuance of long-term debt	375	300
Proceeds from EnerBank notes, net	21	66
Issuance of common stock	22	5
Retirement of long-term debt	(292)	(352)
Payment of common stock dividends	(106)	(69)
Payment of preferred stock dividends	0	(5)
Payment of capital and finance lease obligations	(12)	(12)
Other financing costs	(8)	(44)
Net cash used in financing activities	0	(111)
Net Increase (Decrease) in Cash and Cash Equivalents, Including Assets Held for Sale	745	447
Decrease (Increase) in Cash and Cash Equivalents Included in Assets Held for Sale	2	(1)
Net Increase in Cash and Cash Equivalents	747	446
Cash and Cash Equivalents, Beginning of Period	247	90
Cash and Cash Equivalents, End of Period	994	536
Consumers Energy Company [Member]
Cash Flows from Operating Activities
Net Income	245	195
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	282	301
Deferred income taxes and investment tax credit	82	(22)
Postretirement benefits expense	78	87
Other non-cash operating activities	31	32
Postretirement benefits contributions	(37)	(143)
Changes in other assets and liabilities:
Decrease in accounts receivable, notes receivable, and accrued revenue	207	186
Decrease in accrued power supply revenue	15	22
Decrease in inventories	202	229
Increase (decrease) in accounts payable	42	35
Decrease in accrued expenses	(12)	(13)
Decrease in other current and non-current assets	68	92
Increase (decrease) in other current and non-current liabilities	42	(18)
Net cash provided by operating activities	1,245	983
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(394)	(423)
Cost to retire property	(28)	(21)
Other investing activities	(23)
Net cash used in investing activities	(445)	(444)
Cash Flows from Financing Activities
Retirement of long-term debt	(18)	(327)
Payment of common stock dividends	(196)	(168)
Payment of preferred stock dividends	(1)	(1)
Stockholder's contribution	125	250
Payment of capital and finance lease obligations	(12)	(12)
Other financing costs	(3)
Net cash used in financing activities	(105)	(258)
Net Increase in Cash and Cash Equivalents	695	281
Cash and Cash Equivalents, Beginning of Period	71	39
Cash and Cash Equivalents, End of Period	$ 766	$ 320