Consolidated Statements Of Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Operating Revenue	$ 1,406	$ 1,333	$ 3,385	$ 3,076
Operating Expenses
Fuel for electric generation	147	126	301	256
Purchased and interchange power	347	334	680	651
Purchased power - related parties	23	20	46	42
Cost of gas sold	166	133	773	683
Maintenance and other operating expenses	304	282	586	577
Depreciation and amortization	137	130	318	302
General taxes	50	48	120	117
Total operating expenses	1,174	1,073	2,824	2,628
Operating Income	232	260	561	448
Other Income (Expense)
Interest income	2	1	2	2
Allowance for equity funds used during construction	1	2	4	4
Income from equity method investees	3	3	8	8
Other income	2	3	5	6
Other expense	(3)	(3)	(6)	(5)
Total other income	5	6	13	15
Interest Charges
Interest on long-term debt	99	94	193	188
Other interest expense	4	5	9	11
Allowance for borrowed funds used during construction	(1)	(1)	(2)	(2)
Total interest charges	102	98	200	197
Income Before Income Taxes	135	168	374	266
Income Tax Expense	54	67	149	105
Income From Continuing Operations	81	101	225	161
Income From Discontinued Operations, Net				7
Net Income	81	101	225	168
Income Attributable to Noncontrolling Interests	1	1	1	1
Net Income Attributable to Common Stockholders
Amounts attributable to continuing operations	80	100	224	160
Amounts attributable to discontinued operations				7
Net Income Available to Common Stockholders	80	100	224	167
Income Attributable to Noncontrolling Interests
Amounts attributable to continuing operations	1	1	1	1
Amounts attributable to discontinued operations
Income attributable to noncontrolling interests	1	1	1	1
Basic Earnings Per Average Common Share
Basic earnings from continuing operations	$ 0.30	$ 0.38	$ 0.85	$ 0.61
Basic earnings from discontinued operations				$ 0.03
Basic earnings attributable to common stock	$ 0.30	$ 0.38	$ 0.85	$ 0.64
Diluted Earnings Per Average Common Share
Diluted earnings from continuing operations	$ 0.29	$ 0.37	$ 0.83	$ 0.59
Diluted earnings from discontinued operations				$ 0.03
Diluted earnings attributable to common stock	$ 0.29	$ 0.37	$ 0.83	$ 0.62
Dividends Declared Per Common Share	$ 0.255	$ 0.24	$ 0.51	$ 0.48
Consumers Energy Company [Member]
Operating Revenue	1,342	1,282	3,261	2,957
Operating Expenses
Fuel for electric generation	125	110	258	216
Purchased and interchange power	340	327	669	640
Purchased power - related parties	23	21	46	42
Cost of gas sold	154	124	754	660
Maintenance and other operating expenses	289	266	555	543
Depreciation and amortization	136	128	316	299
General taxes	48	46	117	114
Total operating expenses	1,115	1,022	2,715	2,514
Operating Income	227	260	546	443
Other Income (Expense)
Interest income	2	1	2	2
Allowance for equity funds used during construction	1	2	4	4
Other income	2	3	9	11
Other expense	(3)	(3)	(6)	(5)
Total other income	2	3	9	12
Interest Charges
Interest on long-term debt	60	58	119	119
Other interest expense	3	4	6	8
Allowance for borrowed funds used during construction	(1)	(1)	(2)	(2)
Total interest charges	62	61	123	125
Income Before Income Taxes	167	202	432	330
Income Tax Expense	67	80	170	132
Net Income	100	122	262	198
Preferred Stock Dividends and Distribution	1	1	1	1
Net Income Attributable to Common Stockholders
Net Income Available to Common Stockholders	$ 99	$ 121	$ 261	$ 197