Reportable Segments (Schedule of Financial Information by Reportable Segments, Consumers) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Operating Revenue	$ 2,447	$ 2,176
Power supply cost	615	488
Operating Income	494	412
Total other income	50	86
Total interest charges	186	177
Income (Loss) Before Income Taxes	358	321
Income Tax Expense	63	58
Net Income	304	287
Other segment items	7	22
Net Income (Loss) Available to Common Stockholders	302	285
Total assets	36,295	33,901	$ 35,920
Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue	2,348	2,097
Power supply cost	546	449
Cost of gas sold	382	350
Maintenance and other operating expenses	373	378
Depreciation and amortization	375	356
General taxes	159	152
Total operating expenses	1,835	1,685
Operating Income	513	412
Total other income	46	56
Total interest charges	130	129
Income (Loss) Before Income Taxes	429	339
Income Tax Expense	83	64
Net Income	346	275
Other segment items	0	0
Net Income (Loss) Available to Common Stockholders	346	275
Property, plant, and equipment, gross	33,782	31,820	33,434
Total assets	34,029	32,209	$ 34,088
Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue	2,447	2,176
Power supply cost	615	488
Operating Income	496	415
Total other income	47	62
Total interest charges	130	130
Income (Loss) Before Income Taxes	413	347
Income Tax Expense	103	74
Other segment items	9	24
Net Income (Loss) Available to Common Stockholders	319	297
Total assets	35,877	33,679
Operating Segments | Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue	2,348	2,097
Power supply cost	546	449
Cost of gas sold	382	350
Maintenance and other operating expenses	373	378
Depreciation and amortization	375	356
General taxes	159	152
Total operating expenses	1,835	1,685
Operating Income	513	412
Total other income	46	56
Total interest charges	130	129
Income (Loss) Before Income Taxes	429	339
Income Tax Expense	92	73
Net Income	337	266
Other segment items	0	0
Net Income (Loss) Available to Common Stockholders	337	266
Property, plant, and equipment, gross	33,752	31,792
Total assets	33,998	32,166
Operating Segments | Electric Utility
Segment Reporting Information [Line Items]
Operating Revenue	1,299	1,132
Power supply cost	546	449
Operating Income	202	161
Total other income	27	34
Total interest charges	82	81
Income (Loss) Before Income Taxes	147	114
Income Tax Expense	23	17
Other segment items	0	0
Net Income (Loss) Available to Common Stockholders	124	97
Total assets	20,875	19,759
Operating Segments | Electric Utility | Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue	1,299	1,132
Power supply cost	546	449
Cost of gas sold	0	0
Maintenance and other operating expenses	257	238
Depreciation and amortization	221	213
General taxes	73	71
Total operating expenses	1,097	971
Operating Income	202	161
Total other income	27	34
Total interest charges	82	81
Income (Loss) Before Income Taxes	147	114
Income Tax Expense	23	17
Net Income	124	97
Other segment items	0	0
Net Income (Loss) Available to Common Stockholders	124	97
Property, plant, and equipment, gross	20,340	19,317
Total assets	20,930	19,818
Operating Segments | Gas Utility
Segment Reporting Information [Line Items]
Operating Revenue	1,049	965
Power supply cost	0	0
Operating Income	311	251
Total other income	19	22
Total interest charges	48	48
Income (Loss) Before Income Taxes	282	225
Income Tax Expense	69	56
Other segment items	0	0
Net Income (Loss) Available to Common Stockholders	213	169
Total assets	13,025	12,305
Operating Segments | Gas Utility | Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue	1,049	965
Power supply cost	0	0
Cost of gas sold	382	350
Maintenance and other operating expenses	116	140
Depreciation and amortization	154	143
General taxes	86	81
Total operating expenses	738	714
Operating Income	311	251
Total other income	19	22
Total interest charges	48	48
Income (Loss) Before Income Taxes	282	225
Income Tax Expense	69	56
Net Income	213	169
Other segment items	0	0
Net Income (Loss) Available to Common Stockholders	213	169
Property, plant, and equipment, gross	13,412	12,475
Total assets	13,068	12,348
Other Reconciling Items
Segment Reporting Information [Line Items]
Operating Revenue	0	0
Power supply cost	0	0
Operating Income	(2)	(3)
Total other income	3	24
Total interest charges	56	47
Income (Loss) Before Income Taxes	(55)	(26)
Income Tax Expense	(40)	(16)
Other segment items	(2)	(2)
Net Income (Loss) Available to Common Stockholders	(17)	(12)
Total assets	418	222
Other Reconciling Items | Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue	0	0
Power supply cost	0	0
Cost of gas sold	0	0
Maintenance and other operating expenses	0	0
Depreciation and amortization	0	0
General taxes	0	0
Total operating expenses	0	0
Operating Income	0	0
Total other income	0	0
Total interest charges	0	0
Income (Loss) Before Income Taxes	0	0
Income Tax Expense	(9)	(9)
Net Income	9	9
Other segment items	0	0
Net Income (Loss) Available to Common Stockholders	9	9
Property, plant, and equipment, gross	30	28
Total assets	$ 31	$ 43