Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	$ 1,576	$ 1,514	$ 3,720	$ 3,762
Leasing income	24	27	51	58
Financing income	4	4	8	9
Alternative-revenue programs			4	10
Total operating revenue	1,607	1,555	3,783	3,839
Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,221	1,115	2,350	2,204
Financing income	2	3	4	5
Alternative-revenue programs			4	10
Total operating revenue	1,226	1,128	2,358	2,219
Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	305	356	1,268	1,472
Financing income	2	1	4	4
Alternative-revenue programs			0	0
Total operating revenue	307	357	1,272	1,476
NorthStar Clean Energy | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	50	43	102	86
Leasing income	24	27	51	58
Total operating revenue	74	70	153	144
Variable lease income	13	16	29	38
Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,526	1,471	3,618	3,676
Financing income	4	4	8	9
Alternative-revenue programs	3	10	4	10
Total operating revenue	1,533	1,485	3,630	3,695
Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,221	1,115	2,350	2,204
Financing income	2	3	4	5
Alternative-revenue programs	3	10	4	10
Total operating revenue	1,226	1,128	2,358	2,219
Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	305	356	1,268	1,472
Financing income	2	1	4	4
Alternative-revenue programs	0	0	0	0
Total operating revenue	307	357	1,272	1,476
Residential | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	753	742	1,943	2,046
Residential | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	547	513	1,072	1,041
Residential | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	206	229	871	1,005
Commercial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	497	461	1,064	1,055
Commercial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	433	393	793	740
Commercial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	64	68	271	315
Industrial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	182	167	362	359
Industrial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	174	159	330	320
Industrial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	8	8	32	39
Other
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	50	43	102	86
Other | NorthStar Clean Energy | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	50	43	102	86
Other | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	94	101	249	216
Other | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	67	50	155	103
Other | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	$ 27	$ 51	$ 94	$ 113