Consolidated Statements Of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operating Revenue	$ 1,527	$ 1,587	$ 4,805	$ 4,759
Operating Expenses
Fuel for electric generation	144	145	386	367
Purchased and interchange power	426	454	1,132	1,165
Purchased power - related parties	21	22	64	65
Cost of gas sold	47	45	494	490
Maintenance and other operating expenses	304	301	909	890
Depreciation and amortization	193	183	652	597
General taxes	62	62	209	209
Total operating expenses	1,197	1,212	3,846	3,783
Operating Income	330	375	959	976
Other Income (Expense)
Interest income	3	1	10	4
Allowance for equity funds used during construction	1	3	5	9
Income from equity method investees	3	5	10	12
Nonoperating retirement benefits, net	3	11	10	31
Other income	2	2	4	7
Other expense	(2)	(6)	(6)	(13)
Total other income	10	16	33	50
Interest Charges
Interest on long-term debt	101	103	304	306
Other interest expense	10	8	26	22
Allowance for borrowed funds used during construction		(1)	(2)	(4)
Total interest charges	111	110	328	324
Income Before Income Taxes	229	281	664	702
Income Tax Expense	57	95	200	227
Net Income	172	186	464	475
Income Attributable to Noncontrolling Interests			1	1
Net Income Available to Common Stockholders	$ 172	$ 186	$ 463	$ 474
Basic Earnings Per Average Common Share	$ 0.61	$ 0.67	$ 1.65	$ 1.71
Diluted Earnings Per Average Common Share	0.61	0.67	1.65	1.70
Dividends Declared Per Common Share	$ 0.3325	$ 0.3100	$ 0.9975	$ 0.9300
Consumers Energy Company [Member]
Operating Revenue	$ 1,437	$ 1,498	$ 4,536	$ 4,514
Operating Expenses
Fuel for electric generation	115	118	304	290
Purchased and interchange power	424	445	1,124	1,148
Purchased power - related parties	23	23	67	66
Cost of gas sold	42	39	479	477
Maintenance and other operating expenses	274	274	824	816
Depreciation and amortization	191	182	646	592
General taxes	60	61	203	207
Total operating expenses	1,129	1,142	3,647	3,596
Operating Income	308	356	889	918
Other Income (Expense)
Interest income	2	1	8	3
Interest and dividend income - related parties				1
Allowance for equity funds used during construction	1	3	5	9
Nonoperating retirement benefits, net	3	9	8	28
Other income	1	2	15	7
Other expense	(2)	(6)	(6)	(13)
Total other income	5	9	30	35
Interest Charges
Interest on long-term debt	66	65	198	195
Other interest expense	4	3	11	9
Allowance for borrowed funds used during construction		(1)	(2)	(4)
Total interest charges	70	67	207	200
Income Before Income Taxes	243	298	712	753
Income Tax Expense	62	103	216	254
Net Income	181	195	496	499
Preferred Stock Dividends			1	1
Net Income Available to Common Stockholders	$ 181	$ 195	$ 495	$ 498