Consolidated Statements Of Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Operating Revenue	$ 1,445	$ 1,507	$ 4,830	$ 4,583
Operating Expenses
Fuel for electric generation	165	190	466	446
Purchased and interchange power	383	386	1,063	1,037
Purchased power - related parties	21	23	67	65
Cost of gas sold	76	80	849	763
Maintenance and other operating expenses	285	295	871	872
Depreciation and amortization	145	138	463	440
General taxes	54	53	174	170
Gain on asset sales, net	(1)	(1)	(1)	(1)
Total operating expenses	1,128	1,164	3,952	3,792
Operating Income	317	343	878	791
Other Income (Expense)
Interest income	1	1	3	3
Allowance for equity funds used during construction	1	2	5	6
Income from equity method investees	3	5	11	13
Other income	2	3	7	9
Other expense	(7)	(11)	(13)	(16)
Total other income (expense)			13	15
Interest Charges
Interest on long-term debt	96	92	289	280
Other interest expense	3	5	12	16
Allowance for borrowed funds used during construction		(1)	(2)	(3)
Total interest charges	99	96	299	293
Income Before Income Taxes	218	247	592	513
Income Tax Expense	91	98	240	203
Income From Continuing Operations	127	149	352	310
Income From Discontinued Operations, Net				7
Net Income	127	149	352	317
Income Attributable to Noncontrolling Interests	1	1	2	2
Net Income Attributable to Common Stockholders
Amounts attributable to continuing operations	126	148	350	308
Amounts attributable to discontinued operations				7
Net Income Available to Common Stockholders	126	148	350	315
Income Attributable to Noncontrolling Interests
Amounts attributable to continuing operations	1	1	2	2
Amounts attributable to discontinued operations
Income attributable to noncontrolling interests	1	1	2	2
Basic Earnings Per Average Common Share
Basic earnings from continuing operations	$ 0.48	$ 0.56	$ 1.32	$ 1.18
Basic earnings from discontinued operations				$ 0.03
Basic earnings attributable to common stock	$ 0.48	$ 0.56	$ 1.32	$ 1.21
Diluted Earnings Per Average Common Share
Diluted earnings from continuing operations	$ 0.46	$ 0.55	$ 1.29	$ 1.14
Diluted earnings from discontinued operations				$ 0.03
Diluted earnings attributable to common stock	$ 0.46	$ 0.55	$ 1.29	$ 1.17
Dividends Declared Per Common Share	$ 0.255	$ 0.24	$ 0.765	$ 0.72
Consumers Energy Company [Member]
Operating Revenue	1,386	1,448	4,647	4,405
Operating Expenses
Fuel for electric generation	148	166	406	382
Purchased and interchange power	374	379	1,043	1,019
Purchased power - related parties	21	23	67	65
Cost of gas sold	64	74	818	734
Maintenance and other operating expenses	270	284	825	827
Depreciation and amortization	143	137	459	436
General taxes	53	51	170	165
Gain on asset sales, net	(1)		(1)
Total operating expenses	1,072	1,114	3,787	3,628
Operating Income	314	334	860	777
Other Income (Expense)
Interest income			2	2
Interest and dividend income - related parties	1	1	1	1
Allowance for equity funds used during construction	1	2	5	6
Other income	2	3	11	14
Other expense	(3)	(11)	(9)	(16)
Total other income (expense)	1	(5)	10	7
Interest Charges
Interest on long-term debt	58	56	177	175
Other interest expense	2	4	8	12
Allowance for borrowed funds used during construction		(1)	(2)	(3)
Total interest charges	60	59	183	184
Income Before Income Taxes	255	270	687	600
Income Tax Expense	102	107	272	239
Net Income	153	163	415	361
Preferred Stock Dividends and Distribution	1	1	2	2
Net Income Attributable to Common Stockholders
Net Income Available to Common Stockholders	$ 152	$ 162	$ 413	$ 359