Consolidated Statements Of Income - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Revenue		$ 6,456	$ 7,179	$ 6,566
Operating Expenses
Fuel for electric generation		593	673	621
Purchased and interchange power		1,406	1,602	1,387
Purchased power - related parties		83	90	90
Cost of gas sold		961	1,493	1,228
Maintenance and other operating expenses		1,238	1,232	1,236
Depreciation and amortization		750	685	628
General taxes		262	252	234
Total operating expenses		5,293	6,027	5,424
Operating Income		1,163	1,152	1,142
Other Income (Expense)
Interest income		12	5	3
Allowance for equity funds used during construction		10	8	6
Income from equity method investees	[1]	14	15	13
Other income		10	11	10
Other expense		(17)	(55)	(20)
Total other income (expense)		29	(16)	12
Interest Charges
Interest on long-term debt		386	393	385
Other interest expense		14	17	16
Allowance for borrowed funds used during construction		(4)	(3)	(3)
Total interest charges		396	407	398
Income Before Income Taxes		796	729	756
Income Tax Expense		271	250	302
Net Income		525	479	454
Income Attributable to Noncontrolling Interests		2	2	2
Net Income Available to Common Stockholders		$ 523	$ 477	$ 452
Basic Earnings Per Average Common Share		$ 1.90	$ 1.76	$ 1.71
Diluted Earnings Per Average Common Share		$ 1.89	$ 1.74	$ 1.66
Consumers Energy Company [Member]
Operating Revenue		$ 6,165	$ 6,800	$ 6,321
Operating Expenses
Fuel for electric generation		497	567	541
Purchased and interchange power		1,376	1,564	1,361
Purchased power - related parties		83	89	89
Cost of gas sold		939	1,375	1,187
Maintenance and other operating expenses		1,149	1,146	1,174
Depreciation and amortization		744	678	622
General taxes		255	246	229
Total operating expenses		5,043	5,665	5,203
Operating Income		1,122	1,135	1,118
Other Income (Expense)
Interest income		11	4	2
Interest and dividend income - related parties		1	1	1
Allowance for equity funds used during construction		10	8	6
Other income		19	10	14
Other expense		(17)	(35)	(16)
Total other income (expense)		24	(12)	7
Interest Charges
Interest on long-term debt		252	243	237
Other interest expense		2	10	11
Allowance for borrowed funds used during construction		(4)	(3)	(3)
Total interest charges		250	250	245
Income Before Income Taxes		896	873	880
Income Tax Expense		302	306	346
Net Income		594	567	534
Preferred Stock Dividends and Distribution		2	2	2
Net Income Available to Common Stockholders		$ 592	$ 565	$ 532

[1] Consumers had no significant equity method investments.