Consolidated Statements of Cash Flows (USD $) In Millions	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Cash Flows from Operating Activities
Net Income	$ 376	$ 318
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	404	436
Deferred income taxes and investment tax credit	149	205
Postretirement benefits expense	124	169
Other non-cash operating activities	65	54
Postretirement benefits contributions	(56)	(171)
Changes in other assets and liabilities:
Decrease in accounts receivable, notes receivable, and accrued revenue	280	239
Decrease in accrued power supply revenue	15	2
Decrease (increase) in inventories	(106)	(88)
Decrease in deferred property taxes	133	127
Increase (decrease) in accounts payable	10	(9)
Decrease in accrued expenses	(227)	(187)
Decrease (increase) in other current and non-current assets	(23)	(12)
Increase (decrease) in other current and non-current liabilities	51	(85)
Net cash provided by operating activities	1,195	998
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(624)	(611)
Cost to retire property	(43)	(31)
Cash effect of deconsolidation of partnerships	0	(10)
Increase in EnerBank loans receivable	(60)	(75)
Other investing activities	(25)	1
Net cash used in investing activities	(752)	(726)
Cash Flows from Financing Activities
Proceeds from issuance of long-term debt	375	850
Proceeds from EnerBank notes, net	58	105
Issuance of common stock	26	7
Retirement of long-term debt	(300)	(436)
Payment of net DOE liability	(43)	0
Payment of common stock dividends	(159)	(103)
Payment of preferred stock dividends	0	(8)
Redemption of preferred stock	0	(13)
Payment of capital and finance lease obligations	(18)	(18)
Other financing costs	(8)	(49)
Net cash (used in) provided by financing activities	(69)	335
Net Increase (Decrease) in Cash and Cash Equivalents, Including Assets Held for Sale	374	607
Decrease (Increase) in Cash and Cash Equivalents Included in Assets Held for Sale	2	(1)
Net Increase in Cash and Cash Equivalents	376	606
Cash and Cash Equivalents, Beginning of Period	247	90
Cash and Cash Equivalents, End of Period	623	696
Consumers Energy Company [Member]
Cash Flows from Operating Activities
Net Income	400	355
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	401	432
Deferred income taxes and investment tax credit	85	107
Postretirement benefits expense	117	166
Other non-cash operating activities	52	44
Postretirement benefits contributions	(53)	(161)
Changes in other assets and liabilities:
Decrease in accounts receivable, notes receivable, and accrued revenue	268	241
Decrease in accrued power supply revenue	15	2
Decrease (increase) in inventories	(109)	(90)
Decrease in deferred property taxes	133	127
Increase (decrease) in accounts payable	27	(9)
Decrease in accrued expenses	(126)	(195)
Decrease (increase) in other current and non-current assets	(25)	(9)
Increase (decrease) in other current and non-current liabilities	60	(110)
Net cash provided by operating activities	1,245	900
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(618)	(608)
Cost to retire property	(43)	(31)
Other investing activities	(22)	(1)
Net cash used in investing activities	(683)	(640)
Cash Flows from Financing Activities
Proceeds from issuance of long-term debt	0	300
Retirement of long-term debt	(27)	(335)
Payment of net DOE liability	(43)	0
Payment of common stock dividends	(292)	(259)
Payment of preferred stock dividends	(2)	(2)
Stockholder's contribution	125	250
Payment of capital and finance lease obligations	(18)	(18)
Other financing costs	(3)	(2)
Net cash (used in) provided by financing activities	(260)	(66)
Net Increase in Cash and Cash Equivalents	302	194
Cash and Cash Equivalents, Beginning of Period	71	39
Cash and Cash Equivalents, End of Period	$ 373	$ 233