Consolidated Statements Of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Revenue	$ 6,873	$ 6,583	$ 6,399
Operating Expenses
Fuel for electric generation	528	505	499
Purchased power – related parties	81	86	86
Maintenance and other operating expenses	1,417	1,236	1,248
Depreciation and amortization	933	881	811
General taxes	303	284	281
Total operating expenses	5,711	5,245	5,143
Operating Income	1,162	1,338	1,256
Other Income (Expense)
Interest income	11	12	6
Allowance for equity funds used during construction	6	5	12
Income from equity method investees	9	15	13
Nonoperating retirement benefits, net	90	24	41
Other income	2	6	8
Other expense	(48)	(76)	(75)
Total other income (expense)	70	(14)	5
Interest Charges
Interest on long-term debt	412	406	411
Other interest expense	49	34	29
Allowance for borrowed funds used during construction	(3)	(2)	(5)
Total interest charges	458	438	435
Income Before Income Taxes	774	886	826
Income Tax Expense	115	424	273
Net Income	659	462	553
Income Attributable to Noncontrolling Interests	2	2	2
Net Income Available to Common Stockholders	$ 657	$ 460	$ 551
Basic earnings per average common share (in dollars per share)	$ 2.33	$ 1.64	$ 1.99
Diluted earnings per average common share (in dollars per share)	$ 2.32	$ 1.64	$ 1.98
Consumers Energy Company
Operating Revenue	$ 6,464	$ 6,222	$ 6,064
Operating Expenses
Fuel for electric generation	407	398	393
Purchased and interchange power	1,587	1,491	1,486
Purchased power – related parties	83	90	88
Purchased power – related parties	83	90	88
Cost of gas sold	819	730	693
Maintenance and other operating expenses	1,287	1,113	1,127
Depreciation and amortization	921	872	803
Depreciation and amortization	921	872	803
General taxes	295	276	277
Operating Income	1,065	1,252	1,197
Total operating expenses	5,399	4,970	4,867
Other Income (Expense)
Interest income	8	9	4
Interest and dividend income – related parties	2	1	1
Allowance for equity funds used during construction	6	5	12
Nonoperating retirement benefits, net	83	21	37
Other income	2	17	8
Other expense	(30)	(58)	(55)
Total other income (expense)	71	(5)	7
Interest Charges
Interest on long-term debt	276	263	261
Other interest expense	16	15	12
Allowance for borrowed funds used during construction	(3)	(2)	(5)
Total interest charges	289	276	268
Income Before Income Taxes	847	971	936
Income Tax Expense	142	339	320
Net Income	705	632	616
Preferred Stock Dividends	2	2	2
Net Income Available to Common Stockholders	703	630	614
Purchased and interchange power
Operating Expenses
Cost of goods and services sold	1,613	1,503	1,508
Cost of gas sold
Operating Expenses
Cost of goods and services sold	$ 836	$ 750	$ 710