Consolidated Statements of Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Operating Revenue	$ 1,743	$ 2,055
Operating Expenses
Fuel for electric generation	130	152
Purchased and interchange power	317	300
Purchased power - related parties	22	21
Cost of gas sold	550	768
Maintenance and other operating expenses	295	279
Depreciation and amortization	172	162
General taxes	69	67
Total operating expenses	1,555	1,749
Operating Income	188	306
Other Income (Expense)
Interest income	1	2
Allowance for equity funds used during construction	2	1
Income (loss) from equity method investees	5	4
Other income	3	4
Other expense	(2)	(2)
Total other income	9	9
Interest Charges
Interest on long-term debt	94	100
Other interest expense	6	6
Allowance for borrowed funds used during construction	(1)	(1)
Total interest charges	99	105
Income Before Income Taxes	98	210
Income Tax Expense	38	77
Income from Continuing Operations	60	133
Income From Discontinued Operations, Net of Tax	7	2
Net Income	67	135
Net income available to common stockholders	67	135
Net Income Attributable to Common Stockholders
Amounts attributable to continuing operations	60	133
Amounts attributable to discontinued operations	7	2
Net income available to common stockholders	67	135
Basic Earnings Per Average Common Share
Basic earnings from continuing operations	$ 0.23	$ 0.53
Basic earnings from discontinued operations	$ 0.03	$ 0.01
Basic earnings attributable to common stock	$ 0.26	$ 0.54
Diluted Earnings Per Average Common Share
Diluted earnings from continuing operations	$ 0.22	$ 0.51
Diluted earnings from discontinued operations	$ 0.03	$ 0.01
Diluted earnings attributable to common stock	$ 0.25	$ 0.52
Dividends Declared Per Common Share	$ 0.24	$ 0.21
Consumers Energy Company [Member]
Operating Revenue	1,675	1,988
Operating Expenses
Fuel for electric generation	106	129
Purchased and interchange power	313	293
Purchased power - related parties	21	21
Cost of gas sold	536	753
Maintenance and other operating expenses	277	265
Depreciation and amortization	171	161
General taxes	68	66
Total operating expenses	1,492	1,688
Operating Income	183	300
Other Income (Expense)
Interest income	1	2
Allowance for equity funds used during construction	2	1
Other income	8	8
Other expense	(2)	(2)
Total other income	9	9
Interest Charges
Interest on long-term debt	61	63
Other interest expense	4	4
Allowance for borrowed funds used during construction	(1)	(1)
Total interest charges	64	66
Income Before Income Taxes	128	243
Income Tax Expense	52	90
Net Income	76	153
Net income available to common stockholders	76	153
Net Income Attributable to Common Stockholders
Net income available to common stockholders	$ 76	$ 153