Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	$ 2,318	$ 1,962
Leasing income	58	46
Financing income	5	5
Consumers alternative-revenue programs	(7)
Total operating revenue	2,374	2,013
Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,238	1,131
Financing income	3	3
Consumers alternative-revenue programs	0
Total operating revenue	1,241	1,134
Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,047	801
Financing income	2	2
Consumers alternative-revenue programs	(7)
Total operating revenue	1,042	803
Enterprises | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	33	30
Leasing income	58	46
Total operating revenue	91	76
Variable lease income	44	33
Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	2,285	1,932
Financing income	5	5
Consumers alternative-revenue programs	(7)
Total operating revenue	2,283	1,937
Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,238	1,131
Financing income	3	3
Consumers alternative-revenue programs	0
Total operating revenue	1,241	1,134
Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,047	801
Financing income	2	2
Consumers alternative-revenue programs	(7)
Total operating revenue	1,042	803
Residential | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,331	1,122
Residential | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	591	568
Residential | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	740	554
Commercial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	605	508
Commercial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	384	345
Commercial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	221	163
Industrial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	196	161
Industrial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	168	138
Industrial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	28	23
Other
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	33	30
Other | Enterprises | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	33	30
Other | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	153	141
Other | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	95	80
Other | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	$ 58	$ 61