Reportable Segments (Schedule of Financial Information by Reportable Segments, Consumers) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Operating Revenue	$ 2,021	$ 1,743	$ 6,306	$ 5,526
Power supply cost	687	560	1,905	1,527
Operating Income	481	367	1,292	1,062
Total other income	62	84	249	283
Total interest charges	203	178	588	528
Income (Loss) Before Income Taxes	340	273	953	817
Income Tax Expense	68	26	193	125
Net Income	277	253	782	738
Other segment items	3	4	15	39
Net Income (Loss) Available to Common Stockholders	275	251	775	731
Total assets	38,008	34,817	38,008	34,817	$ 35,920
Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue	1,913	1,661	6,007	5,291
Power supply cost	624	515	1,707	1,408
Cost of gas sold	40	31	545	447
Maintenance and other operating expenses	388	381	1,137	1,136
Depreciation and amortization	274	261	925	878
General taxes	104	95	369	346
Total operating expenses	1,430	1,283	4,683	4,215
Operating Income	483	378	1,324	1,076
Total other income	55	60	161	175
Total interest charges	145	131	416	386
Income (Loss) Before Income Taxes	393	307	1,069	865
Income Tax Expense	79	34	221	139
Net Income	314	273	848	726
Other segment items			(1)	(1)
Net Income (Loss) Available to Common Stockholders	314	273	847	725
Property, plant, and equipment, gross	35,021	32,695	35,021	32,695	33,434
Total assets	35,780	33,160	35,780	33,160	$ 34,088
Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue	2,021	1,743	6,306	5,526
Power supply cost	687	560	1,905	1,527
Operating Income	484	371	1,300	1,072
Total other income	60	63	168	186
Total interest charges	144	133	413	388
Income (Loss) Before Income Taxes	400	301	1,055	870
Income Tax Expense	68	17	207	128
Other segment items	5	6	22	46
Net Income (Loss) Available to Common Stockholders	337	290	870	788
Total assets	37,866	34,742	37,866	34,742
Operating Segments | Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue	1,913	1,661	6,007	5,291
Power supply cost	624	515	1,707	1,408
Cost of gas sold	40	31	545	447
Maintenance and other operating expenses	388	381	1,137	1,136
Depreciation and amortization	274	261	925	877
General taxes	104	95	369	346
Total operating expenses	1,430	1,283	4,683	4,214
Operating Income	483	378	1,324	1,077
Total other income	56	60	161	175
Total interest charges	145	131	415	385
Income (Loss) Before Income Taxes	394	307	1,070	867
Income Tax Expense	68	23	214	131
Net Income			856	736
Other segment items			(1)	(1)
Net Income (Loss) Available to Common Stockholders	326	284	855	735
Property, plant, and equipment, gross	34,985	32,666	34,985	32,666
Total assets	35,734	33,131	35,734	33,131
Operating Segments | Electric Utility
Segment Reporting Information [Line Items]
Operating Revenue	1,679	1,448	4,337	3,806
Power supply cost	624	515	1,707	1,408
Operating Income	450	347	915	752
Total other income	34	35	97	105
Total interest charges	92	82	263	242
Income (Loss) Before Income Taxes	392	300	749	615
Income Tax Expense	66	27	131	74
Other segment items	0	0	(1)	(1)
Net Income (Loss) Available to Common Stockholders	326	273	617	540
Total assets	21,917	20,222	21,917	20,222
Operating Segments | Electric Utility | Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue	1,679	1,448	4,337	3,806
Power supply cost	624	515	1,707	1,408
Cost of gas sold	0	0	0	0
Maintenance and other operating expenses	285	282	806	781
Depreciation and amortization	239	229	682	651
General taxes	81	75	227	214
Total operating expenses	1,229	1,101	3,422	3,054
Operating Income	450	347	915	752
Total other income	34	35	97	105
Total interest charges	92	82	263	242
Income (Loss) Before Income Taxes	392	300	749	615
Income Tax Expense	66	27	131	74
Net Income			618	541
Other segment items			(1)	(1)
Net Income (Loss) Available to Common Stockholders	326	273	617	540
Property, plant, and equipment, gross	21,095	19,826	21,095	19,826
Total assets	21,972	20,279	21,972	20,279
Operating Segments | Gas Utility
Segment Reporting Information [Line Items]
Operating Revenue	234	213	1,670	1,485
Power supply cost	0	0	0	0
Operating Income	33	31	409	325
Total other income	22	25	64	70
Total interest charges	53	49	152	143
Income (Loss) Before Income Taxes	2	7	321	252
Income Tax Expense	2	(4)	83	57
Other segment items	0	0	0	0
Net Income (Loss) Available to Common Stockholders	0	11	238	195
Total assets	13,720	12,809	13,720	12,809
Operating Segments | Gas Utility | Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue	234	213	1,670	1,485
Power supply cost	0	0	0	0
Cost of gas sold	40	31	545	447
Maintenance and other operating expenses	103	99	331	355
Depreciation and amortization	35	32	243	226
General taxes	23	20	142	132
Total operating expenses	201	182	1,261	1,160
Operating Income	33	31	409	325
Total other income	22	25	64	70
Total interest charges	53	49	152	143
Income (Loss) Before Income Taxes	2	7	321	252
Income Tax Expense	2	(4)	83	57
Net Income			238	195
Other segment items			0	0
Net Income (Loss) Available to Common Stockholders	0	11	238	195
Property, plant, and equipment, gross	13,890	12,840	13,890	12,840
Total assets	13,762	12,852	13,762	12,852
Other Reconciling Items
Segment Reporting Information [Line Items]
Operating Revenue	0	0	0	0
Power supply cost	0	0	0	0
Operating Income	(3)	(4)	(8)	(10)
Total other income	2	21	81	97
Total interest charges	59	45	175	140
Income (Loss) Before Income Taxes	(60)	(28)	(102)	(53)
Income Tax Expense	0	9	(14)	(3)
Other segment items	(2)	(2)	(7)	(7)
Net Income (Loss) Available to Common Stockholders	(62)	(39)	(95)	(57)
Total assets	142	75	142	75
Other Reconciling Items | Consumers Energy Company
Segment Reporting Information [Line Items]
Operating Revenue	0	0	0	0
Power supply cost	0	0	0	0
Cost of gas sold	0	0	0	0
Maintenance and other operating expenses	0	0	0	0
Depreciation and amortization	0	0	0	1
General taxes	0	0	0	0
Total operating expenses	0	0	0	1
Operating Income	0	0	0	(1)
Total other income	(1)	0	0	0
Total interest charges	0	0	1	1
Income (Loss) Before Income Taxes	(1)	0	(1)	(2)
Income Tax Expense	11	11	7	8
Net Income			(8)	(10)
Other segment items			0	0
Net Income (Loss) Available to Common Stockholders	(12)	(11)	(8)	(10)
Property, plant, and equipment, gross	36	29	36	29
Total assets	$ 46	$ 29	$ 46	$ 29