Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									$ 7,075	$ 6,238	$ 6,403
Leasing income									194	148	174
Financing income									15	17	14
Consumers alternative-revenue programs									45	43	33
Consumers revenues to be refunded										(28)
Total operating revenue	$ 2,033	$ 1,725	$ 1,558	$ 2,013	$ 1,727	$ 1,507	$ 1,382	$ 1,802	7,329	6,418	6,624
Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									4,915	4,348	4,407
Financing income									10	11	9
Consumers alternative-revenue programs									33	29	23
Consumers revenues to be refunded										(16)
Total operating revenue									4,958	4,372	4,439
Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									2,046	1,809	1,922
Financing income									5	6	5
Consumers alternative-revenue programs									12	14	10
Consumers revenues to be refunded										(12)
Total operating revenue									2,063	1,817	1,937
Enterprises | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									114	81	74
Leasing income									194	148	174
Total operating revenue									308	229	248
Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									6,961	6,157	6,329
Financing income									15	17	14
Consumers alternative-revenue programs									45	43	33
Consumers revenues to be refunded										(28)
Total operating revenue									7,021	6,189	6,376
Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									4,915	4,348	4,407
Financing income									10	11	9
Consumers alternative-revenue programs									33	29	23
Consumers revenues to be refunded										(16)
Total operating revenue									4,958	4,372	4,439
Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									2,046	1,809	1,922
Financing income									5	6	5
Consumers alternative-revenue programs									12	14	10
Consumers revenues to be refunded										(12)
Total operating revenue									2,063	1,817	1,937
Residential | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									3,798	3,341	3,304
Residential | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									2,402	2,109	1,988
Residential | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									1,396	1,232	1,316
Commercial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									1,969	1,781	1,874
Commercial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									1,573	1,444	1,502
Commercial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									396	337	372
Industrial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									678	616	720
Industrial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									624	570	669
Industrial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									54	46	51
Other
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									114	81	74
Other | Enterprises | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									114	81	74
Other | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									516	419	431
Other | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									316	225	248
Other | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers									$ 200	$ 194	$ 183