Reportable Segments (Schedule of Financial Information by Reportable Segments, Consumers) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Operating Revenue	$ 7,515	$ 7,462	$ 8,596
Power supply cost	2,028	2,011	2,909
Operating Income	1,487	1,235	1,224
Total other income	344	362	197
Total interest charges	708	643	519
Income (Loss) Before Income Taxes	1,123	954	902
Income Tax Expense	176	147	93
Net Income	1,003	887	837
Other segment items	46	70	18
Net Income (Loss) Available to Common Stockholders	993	877	827
Total assets	35,920	33,517
Capital expenditures	3,301	3,280
Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue	7,200	7,166	8,151
Power supply cost	1,867	1,841	2,605
Cost of gas sold	637	897	1,243
Maintenance and other operating expenses	1,520	1,586	1,582
Depreciation and amortization	1,191	1,137	1,088
General taxes	470	437	400
Total operating expenses	5,685	5,898	6,918
Operating Income	1,515	1,268	1,233
Total other income	212	208	187
Total interest charges	518	448	335
Income (Loss) Before Income Taxes	1,209	1,028	1,085
Income Tax Expense	200	161	140
Net Income	1,009	867	945
Other segment items	(2)	(2)	(2)
Net Income (Loss) Available to Common Stockholders	1,007	865	943
Plant, property, and equipment, gross	33,434	31,723
Total assets	34,088	31,852
Capital expenditures	3,012	3,145
Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue	7,515	7,462	8,596
Power supply cost	2,028	2,011	2,909
Operating Income	1,506	1,251	1,237
Total other income	226	220	199
Total interest charges	520	448	337
Income (Loss) Before Income Taxes	1,212	1,023	1,099
Income Tax Expense	196	169	144
Other segment items	56	78	24
Net Income (Loss) Available to Common Stockholders	1,072	932	979
Total assets	35,850	33,315
Capital expenditures	3,300	3,278
Operating Segments | Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue	7,199	7,165	8,151
Power supply cost	1,867	1,841	2,605
Cost of gas sold	637	897	1,243
Maintenance and other operating expenses	1,520	1,586	1,582
Depreciation and amortization	1,190	1,135	1,087
General taxes	469	436	399
Total operating expenses	5,683	5,895	6,916
Operating Income	1,516	1,270	1,235
Total other income	212	208	187
Total interest charges	516	446	334
Income (Loss) Before Income Taxes	1,212	1,032	1,088
Income Tax Expense	201	165	141
Net Income	1,011	867	947
Other segment items	(2)	(2)	(2)
Net Income (Loss) Available to Common Stockholders	1,009	865	945
Plant, property, and equipment, gross	33,405	31,685
Total assets	34,056	31,814
Capital expenditures	3,012	3,122
Operating Segments | Electric Utility
Segment Reporting Information [Line Items]
Operating Revenue	5,061	4,745	5,419
Power supply cost	1,867	1,841	2,605
Operating Income	982	772	789
Total other income	126	131	106
Total interest charges	324	285	218
Income (Loss) Before Income Taxes	784	618	677
Income Tax Expense	102	67	109
Other segment items	(1)	(1)	(1)
Net Income (Loss) Available to Common Stockholders	681	550	567
Total assets	20,710	19,358
Capital expenditures	1,871	2,081
Operating Segments | Electric Utility | Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue	5,061	4,745	5,419
Power supply cost	1,867	1,841	2,605
Cost of gas sold	0	0	0
Maintenance and other operating expenses	1,066	1,075	1,028
Depreciation and amortization	865	797	757
General taxes	281	260	240
Total operating expenses	4,079	3,973	4,630
Operating Income	982	772	789
Total other income	126	131	106
Total interest charges	324	285	218
Income (Loss) Before Income Taxes	784	618	677
Income Tax Expense	102	67	109
Net Income	682	551	568
Other segment items	(1)	(1)	(1)
Net Income (Loss) Available to Common Stockholders	681	550	567
Plant, property, and equipment, gross	20,137	19,302
Total assets	20,767	19,417
Capital expenditures	1,871	2,081
Operating Segments | Gas Utility
Segment Reporting Information [Line Items]
Operating Revenue	2,138	2,420	2,732
Power supply cost	0	0	0
Operating Income	534	498	446
Total other income	86	77	81
Total interest charges	192	161	116
Income (Loss) Before Income Taxes	428	414	411
Income Tax Expense	99	98	32
Other segment items	(1)	(1)	(1)
Net Income (Loss) Available to Common Stockholders	328	315	378
Total assets	13,247	12,353
Capital expenditures	1,141	1,041
Operating Segments | Gas Utility | Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue	2,138	2,420	2,732
Power supply cost	0	0	0
Cost of gas sold	637	897	1,243
Maintenance and other operating expenses	454	511	554
Depreciation and amortization	325	338	330
General taxes	188	176	159
Total operating expenses	1,604	1,922	2,286
Operating Income	534	498	446
Total other income	86	77	81
Total interest charges	192	161	116
Income (Loss) Before Income Taxes	428	414	411
Income Tax Expense	99	98	32
Net Income	329	316	379
Other segment items	(1)	(1)	(1)
Net Income (Loss) Available to Common Stockholders	328	315	378
Plant, property, and equipment, gross	13,268	12,383
Total assets	13,289	12,397
Capital expenditures	1,141	1,041
Other Reconciling Items
Segment Reporting Information [Line Items]
Operating Revenue	0	0	0
Power supply cost	0	0	0
Operating Income	(19)	(16)	(13)
Total other income	118	142	(2)
Total interest charges	188	195	182
Income (Loss) Before Income Taxes	(89)	(69)	(197)
Income Tax Expense	(20)	(22)	(51)
Other segment items	(10)	(8)	(6)
Net Income (Loss) Available to Common Stockholders	(79)	(55)	(152)
Total assets	70	202
Capital expenditures	1	2
Other Reconciling Items | Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue	1	1	0
Power supply cost	0	0	0
Cost of gas sold	0	0	0
Maintenance and other operating expenses	0	0	0
Depreciation and amortization	1	2	1
General taxes	1	1	1
Total operating expenses	2	3	2
Operating Income	(1)	(2)	(2)
Total other income	0	0	0
Total interest charges	2	2	1
Income (Loss) Before Income Taxes	(3)	(4)	(3)
Income Tax Expense	(1)	(4)	(1)
Net Income	(2)	0	(2)
Other segment items	0	0	0
Net Income (Loss) Available to Common Stockholders	(2)	0	$ (2)
Plant, property, and equipment, gross	29	38
Total assets	32	38
Capital expenditures	$ 0	$ 23