Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	$ 1,514	$ 1,842	$ 3,762	$ 4,160
Leasing income	27	66	58	124
Financing income	4	4	9	9
Consumers alternative-revenue programs			10	1
Total operating revenue	1,555	1,920	3,839	4,294
Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,115	1,322	2,204	2,560
Financing income	3	2	5	5
Consumers alternative-revenue programs			10	1
Total operating revenue	1,128	1,325	2,219	2,566
Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	356	468	1,472	1,515
Financing income	1	2	4	4
Consumers alternative-revenue programs			0	0
Total operating revenue	357	477	1,476	1,519
NorthStar Clean Energy | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	43	52	86	85
Leasing income	27	66	58	124
Total operating revenue	70	118	144	209
Variable lease income	16	53	38	97
Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,471	1,790	3,676	4,075
Financing income	4	4	9	9
Consumers alternative-revenue programs	10	8	10	1
Total operating revenue	1,485	1,802	3,695	4,085
Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,115	1,322	2,204	2,560
Financing income	3	2	5	5
Consumers alternative-revenue programs	10	1	10	1
Total operating revenue	1,128	1,325	2,219	2,566
Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	356	468	1,472	1,515
Financing income	1	2	4	4
Consumers alternative-revenue programs	0	7	0	0
Total operating revenue	357	477	1,476	1,519
Residential | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	742	906	2,046	2,237
Residential | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	513	597	1,041	1,188
Residential | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	229	309	1,005	1,049
Commercial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	461	519	1,055	1,124
Commercial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	393	420	740	804
Commercial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	68	99	315	320
Industrial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	167	222	359	418
Industrial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	159	207	320	375
Industrial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	8	15	39	43
Other
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	43	52	86	85
Other | NorthStar Clean Energy | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	43	52	86	85
Other | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	101	143	216	296
Other | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	50	98	103	193
Other | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	$ 51	$ 45	$ 113	$ 103