Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	$ 2,144	$ 2,248
Leasing income	27	31
Financing income	4	5
Alternative-revenue programs	1
Total operating revenue	2,176	2,284
Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,129	1,089
Financing income	2	2
Alternative-revenue programs	1
Total operating revenue	1,132	1,091
Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	963	1,116
Financing income	2	3
Alternative-revenue programs	0
Total operating revenue	965	1,119
NorthStar Clean Energy | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	52	43
Leasing income	27	31
Total operating revenue	79	74
Variable lease income	16	22
Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	2,092	2,205
Financing income	4	5
Alternative-revenue programs	1
Total operating revenue	2,097	2,210
Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,129	1,089
Financing income	2	2
Alternative-revenue programs	1
Total operating revenue	1,132	1,091
Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	963	1,116
Financing income	2	3
Alternative-revenue programs	0
Total operating revenue	965	1,119
Residential | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,190	1,304
Residential | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	525	528
Residential | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	665	776
Commercial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	567	594
Commercial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	360	347
Commercial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	207	247
Industrial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	180	192
Industrial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	156	161
Industrial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	24	31
Other
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	52	43
Other | NorthStar Clean Energy | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	52	43
Other | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	155	115
Other | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	88	53
Other | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	$ 67	$ 62