Consolidated Statements Of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Revenue	$ 6,680	$ 6,845	$ 6,873
Operating Expenses
Fuel for electric generation	375	493	528
Purchased power – related parties	64	75	81
Maintenance and other operating expenses	1,403	1,448	1,417
Depreciation and amortization	1,048	992	933
General taxes	359	333	303
Total operating expenses	5,318	5,606	5,711
Operating Income	1,362	1,239	1,162
Other Income (Expense)
Interest income	4	7	11
Interest and dividend income – related parties	7	0	0
Allowance for equity funds used during construction	6	10	6
Income from equity method investees	5	10	9
Nonoperating retirement benefits, net	118	91	90
Other income	6	4	2
Other expense	(62)	(13)	(48)
Total other income	84	109	70
Interest Charges
Interest on long-term debt	483	439	412
Interest expense – related parties	12	9	0
Other interest expense	68	75	49
Allowance for borrowed funds used during construction	(2)	(4)	(3)
Total interest charges	561	519	458
Income Before Income Taxes	885	829	774
Income Tax Expense	133	147	115
Net Income	752	682	659
Income (Loss) Attributable to Noncontrolling Interests	(3)	2	2
Net Income Available to Common Stockholders	$ 755	$ 680	$ 657
Basic earnings per average common share (in dollars per share)	$ 2.65	$ 2.40	$ 2.33
Diluted earnings per average common share (in dollars per share)	$ 2.64	$ 2.39	$ 2.32
Consumers Energy Company
Operating Revenue	$ 6,189	$ 6,376	$ 6,464
Operating Expenses
Fuel for electric generation	286	375	407
Purchased and interchange power	1,454	1,470	1,587
Purchased power – related parties	64	75	83
Cost of gas sold	568	754	819
Maintenance and other operating expenses	1,224	1,275	1,287
Depreciation and amortization	1,023	975	921
General taxes	349	322	295
Total operating expenses	4,968	5,246	5,399
Operating Income	1,221	1,130	1,065
Other Income (Expense)
Interest income	3	5	8
Interest and dividend income – related parties	5	5	2
Allowance for equity funds used during construction	6	10	6
Nonoperating retirement benefits, net	112	85	83
Other income	5	3	2
Other expense	(43)	(13)	(30)
Total other income	88	95	71
Interest Charges
Interest on long-term debt	299	277	276
Interest expense – related parties	12	9	0
Other interest expense	11	15	16
Allowance for borrowed funds used during construction	(2)	(4)	(3)
Total interest charges	320	297	289
Income Before Income Taxes	989	928	847
Income Tax Expense	173	185	142
Net Income	816	743	705
Preferred Stock Dividends	2	2	2
Net Income Available to Common Stockholders	814	741	703
Purchased and interchange power
Operating Expenses
Cost of goods and services sold	1,492	1,496	1,613
Cost of gas sold
Operating Expenses
Cost of goods and services sold	$ 577	$ 769	$ 836