Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	$ 1,842	$ 1,515	$ 4,160	$ 3,477
Leasing income	66	40	124	86
Financing income	4	3	9	8
Consumers alternative-revenue programs			1
Total operating revenue	1,920	1,558	4,294	3,571
Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,322	1,158	2,560	2,289
Financing income	2	2	5	5
Consumers alternative-revenue programs			1
Total operating revenue	1,325	1,160	2,566	2,294
Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	468	332	1,515	1,133
Financing income	2	1	4	3
Consumers alternative-revenue programs			0
Total operating revenue	477	333	1,519	1,136
Enterprises | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	52	25	85	55
Leasing income	66	40	124	86
Total operating revenue	118	65	209	141
Variable lease income	53	26	97	59
Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,790	1,490	4,075	3,422
Financing income	4	3	9	8
Consumers alternative-revenue programs	8		1
Total operating revenue	1,802	1,493	4,085	3,430
Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,322	1,158	2,560	2,289
Financing income	2	2	5	5
Consumers alternative-revenue programs	1		1
Total operating revenue	1,325	1,160	2,566	2,294
Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	468	332	1,515	1,133
Financing income	2	1	4	3
Consumers alternative-revenue programs	7		0
Total operating revenue	477	333	1,519	1,136
Residential | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	906	781	2,237	1,903
Residential | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	597	561	1,188	1,129
Residential | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	309	220	1,049	774
Commercial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	519	449	1,124	957
Commercial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	420	390	804	735
Commercial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	99	59	320	222
Industrial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	222	161	418	322
Industrial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	207	153	375	291
Industrial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	15	8	43	31
Other
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	52	25	85	55
Other | Enterprises | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	52	25	85	55
Other | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	143	99	296	240
Other | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	98	54	193	134
Other | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	$ 45	$ 45	$ 103	$ 106