Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	$ 1,975	$ 1,711	$ 6,171	$ 5,431
Leasing income	41	26	117	77
Financing income	3	5	12	13
Total operating revenue	2,021	1,743	6,306	5,526
Operating Segments
Disaggregation of Revenue [Line Items]
Total operating revenue	2,021	1,743	6,306	5,526
Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,675	1,443	4,324	3,793
Financing income	2	4	7	8
Total operating revenue	1,679	1,448	4,337	3,806
Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	233	212	1,665	1,480
Financing income	1	1	5	5
Total operating revenue	234	213	1,670	1,485
NorthStar Clean Energy | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	67	56	182	158
Leasing income	41	26	117	77
Total operating revenue	108	82	299	235
Variable lease income	28	15
NorthStar Clean Energy | Operating Segments | Power Sales Agreement
Disaggregation of Revenue [Line Items]
Variable lease income			82	44
Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,908	1,655	5,989	5,273
Financing income	3	5	12	13
Alternative-revenue programs	2	1	6	5
Total operating revenue	1,913	1,661	6,007	5,291
Consumers Energy Company | Operating Segments
Disaggregation of Revenue [Line Items]
Total operating revenue	1,913	1,661	6,007	5,291
Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	1,675	1,443	4,324	3,793
Financing income	2	4	7	8
Alternative-revenue programs	2	1	6	5
Total operating revenue	1,679	1,448	4,337	3,806
Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	233	212	1,665	1,480
Financing income	1	1	5	5
Alternative-revenue programs	0	0	0	0
Total operating revenue	234	213	1,670	1,485
Residential | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	981	834	3,201	2,777
Residential | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	842	707	2,055	1,779
Residential | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	139	127	1,146	998
Commercial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	622	526	1,842	1,590
Commercial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	577	486	1,468	1,279
Commercial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	45	40	374	311
Industrial | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	210	174	622	536
Industrial | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	204	169	576	499
Industrial | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	6	5	46	37
Other
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	67	56	182	158
Other | NorthStar Clean Energy | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	67	56	182	158
Other | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	95	121	324	370
Other | Consumers Energy Company | Electric Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	52	81	225	236
Other | Consumers Energy Company | Gas Utility | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue recognized from contracts with customers	$ 43	$ 40	$ 99	$ 134