Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	$ 1,639	$ 1,955	$ 5,401	$ 6,115
Leasing income	30	68	88	192
Financing income	3	4	12	13
Consumers alternative-revenue programs			11	(2)
Total operating revenue	1,673	2,024	5,512	6,318
Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,348	1,591	3,552	4,151
Financing income	2	3	7	8
Consumers alternative-revenue programs			11	1
Total operating revenue	1,351	1,594	3,570	4,160
Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	243	294	1,715	1,809
Financing income	1	1	5	5
Consumers alternative-revenue programs			0	(3)
Total operating revenue	244	292	1,720	1,811
NorthStar Clean Energy | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	48	70	134	155
Leasing income	30	68	88	192
Total operating revenue	78	138	222	347
Variable lease income	19	57	57	154
Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,591	1,885	5,267	5,960
Financing income	3	4	12	13
Consumers alternative-revenue programs	1	(3)	11	(2)
Other non-segment revenue	1		1
Total operating revenue	1,596	1,886	5,291	5,971
Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,348	1,591	3,552	4,151
Financing income	2	3	7	8
Consumers alternative-revenue programs	1	0	11	1
Total operating revenue	1,351	1,594	3,570	4,160
Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	243	294	1,715	1,809
Financing income	1	1	5	5
Consumers alternative-revenue programs	0	(3)	0	(3)
Total operating revenue	244	292	1,720	1,811
Residential | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	821	957	2,867	3,194
Residential | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	666	767	1,707	1,955
Residential | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	155	190	1,160	1,239
Commercial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	481	566	1,536	1,690
Commercial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	443	515	1,183	1,319
Commercial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	38	51	353	371
Industrial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	180	236	539	654
Industrial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	175	226	495	601
Industrial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	5	10	44	53
Other
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	48	70	134	155
Other | NorthStar Clean Energy | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	48	70	134	155
Other | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	109	126	325	422
Other | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	64	83	167	276
Other | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	$ 45	$ 43	$ 158	$ 146