Reportable Segments (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Operating Revenue	$ 2,033	$ 1,725	$ 1,558	$ 2,013	$ 1,727	$ 1,507	$ 1,382	$ 1,802	$ 7,329	$ 6,418	$ 6,624
Depreciation and amortization									1,114	1,043	989
Income from equity method investees									10	5	10
Interest charges									500	505	460
Income tax expense (benefit)									95	115	131
Net income (loss) available to common stockholders	637	$ 186	$ 176	$ 349	158	$ 218	$ 136	$ 243	1,348	755	680
Plant, property, and equipment, gross	29,893				27,870				29,893	27,870	25,368
Investments in equity method investees	71				70				71	70	71
Total assets	28,753				29,666				28,753	29,666	26,837
Capital expenditures									2,161	2,275	2,139
Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue									7,021	6,189	6,376
Depreciation and amortization									1,077	1,023	975
Interest charges									311	320	297
Income tax expense (benefit)									156	173	185
Net income (loss) available to common stockholders									866	814	741
Plant, property, and equipment, gross	28,771				26,757				28,771	26,757	24,963
Total assets	27,140				25,399				27,140	25,399	23,699
Capital expenditures									2,144	2,167	2,134
Other reconciling items
Segment Reporting Information [Line Items]
Depreciation and amortization									1	1	1
Interest charges									183	179	157
Income tax expense (benefit)									(59)	(54)	(56)
Net income (loss) available to common stockholders									458	(96)	(95)
Plant, property, and equipment, gross	23				21				23	21	20
Total assets	431				3,132				431	3,132	2,740
Capital expenditures									2	1	1
Other reconciling items | Consumers Energy Company
Segment Reporting Information [Line Items]
Depreciation and amortization									1	1	1
Interest charges									0	1	1
Net income (loss) available to common stockholders									(1)	(1)	(1)
Plant, property, and equipment, gross	23				21				23	21	20
Total assets	21				29				21	29	20
Capital expenditures									2	1	1
Electric Utility | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue									4,958	4,372	4,439
Depreciation and amortization									772	739	713
Interest charges									207	217	213
Income tax expense (benefit)									117	115	134
Net income (loss) available to common stockholders									565	554	509
Plant, property, and equipment, gross	18,147				17,155				18,147	17,155	16,158
Total assets	16,493				15,829				16,493	15,829	14,911
Capital expenditures									1,153	1,281	1,162
Electric Utility | Operating Segments | Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue									4,958	4,372	4,439
Depreciation and amortization									772	739	713
Interest charges									207	217	213
Income tax expense (benefit)									117	115	134
Net income (loss) available to common stockholders									565	554	509
Plant, property, and equipment, gross	18,147				17,155				18,147	17,155	16,158
Total assets	16,555				15,893				16,555	15,893	14,973
Capital expenditures									1,153	1,281	1,162
Gas Utility | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue									2,063	1,817	1,937
Depreciation and amortization									304	283	261
Interest charges									104	102	83
Income tax expense (benefit)									39	58	51
Net income (loss) available to common stockholders									302	261	233
Plant, property, and equipment, gross	10,601				9,581				10,601	9,581	8,785
Total assets	10,517				9,429				10,517	9,429	8,659
Capital expenditures									989	885	971
Gas Utility | Operating Segments | Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue									2,063	1,817	1,937
Depreciation and amortization									304	283	261
Interest charges									104	102	83
Income tax expense (benefit)									39	58	51
Net income (loss) available to common stockholders									302	261	233
Plant, property, and equipment, gross	10,601				9,581				10,601	9,581	8,785
Total assets	10,564				9,477				10,564	9,477	8,706
Capital expenditures									989	885	971
Enterprises | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue									308	229	248
Depreciation and amortization									37	20	14
Income from equity method investees									10	5	10
Interest charges									6	7	7
Income tax expense (benefit)									(2)	(4)	2
Net income (loss) available to common stockholders									23	36	33
Plant, property, and equipment, gross	1,122				1,113				1,122	1,113	405
Investments in equity method investees	71				70				71	70	71
Total assets	$ 1,312				$ 1,276				1,312	1,276	527
Capital expenditures									$ 17	$ 108	$ 5