Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	$ 7,261	$ 8,320	$ 7,075
Leasing income	116	240	194
Financing income	16	16	15
Alternative-revenue programs	69	57	45
Revenues to be refunded		(37)
Total operating revenue	7,462	8,596	7,329
Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	4,686	5,395	4,915
Financing income	10	10	10
Alternative-revenue programs	49	43	33
Revenues to be refunded		(29)
Total operating revenue	4,745	5,419	4,958
Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	2,394	2,720	2,046
Financing income	6	6	5
Alternative-revenue programs	20	14	12
Revenues to be refunded		(8)
Total operating revenue	2,420	2,732	2,063
NorthStar Clean Energy | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	181	205	114
Leasing income	116	240	194
Total operating revenue	297	445	308
Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	7,080	8,115	6,961
Financing income	16	16	15
Alternative-revenue programs	69	57	45
Revenues to be refunded		(37)
Other non-segment revenue	1
Total operating revenue	7,166	8,151	7,021
Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	4,686	5,395	4,915
Financing income	10	10	10
Alternative-revenue programs	49	43	33
Revenues to be refunded		(29)
Total operating revenue	4,745	5,419	4,958
Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	2,394	2,720	2,046
Financing income	6	6	5
Alternative-revenue programs	20	14	12
Revenues to be refunded		(8)
Total operating revenue	2,420	2,732	2,063
Residential | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	3,855	4,402	3,798
Residential | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	2,236	2,523	2,402
Residential | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,619	1,879	1,396
Commercial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	2,039	2,292	1,969
Commercial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,550	1,733	1,573
Commercial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	489	559	396
Industrial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	720	867	678
Industrial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	660	792	624
Industrial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	60	75	54
Other
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	181	205	114
Other | NorthStar Clean Energy | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	181	205	114
Other | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	466	554	516
Other | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	240	347	316
Other | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	$ 226	$ 207	$ 200