Financings and Capitalization (Summary of Long-Term Debt) (Details) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended
	Dec. 01, 2030	Jun. 01, 2030	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Total principal amount outstanding			$ 16,545	$ 15,648
Current amounts			(1,192)	(975)
Long-term debt - related parties principal amount outstanding			(1,790)
Unamortized discounts			(29)	(30)
Unamortized issuance costs			(130)	(135)
Long-term debt			15,194	14,508
Consumers Energy Company
Debt Instrument [Line Items]
Total principal amount outstanding			12,205	11,294
Current amounts			(452)	(725)
Long-term debt - related parties principal amount outstanding			(1,300)
Unamortized discounts			(27)	(28)
Unamortized issuance costs			(73)	(73)
Consumers Energy Company | Related Party
Debt Instrument [Line Items]
Long-term debt - related parties principal amount outstanding			(835)	(431)
Long-term debt			823	424
Consumers Energy Company | Nonrelated Party
Debt Instrument [Line Items]
Long-term debt			10,818	10,037
First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Total principal amount outstanding			11,395	10,397
First mortgage bonds | Consumers Energy Company | Related Party
Debt Instrument [Line Items]
Long-term debt - related parties principal amount outstanding			(404)	(431)
Unamortized discounts			(5)	(3)
Unamortized issuance costs			(7)	(4)
Tax-exempt revenue bonds | Consumers Energy Company
Debt Instrument [Line Items]
Total principal amount outstanding			110	110
Securitization bonds | Consumers Energy Company
Debt Instrument [Line Items]
Total principal amount outstanding			$ 700	787
3.125% First Mortgage Bonds Due 2024 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			3.125%
Total principal amount outstanding			$ 0	250
3.190% First Mortgage Bonds Due 2024 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			3.19%
Total principal amount outstanding			$ 0	52
5.240 First Mortgage Bonds Due 2026 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			5.24%
Total principal amount outstanding			$ 115	115
3.680% First Mortgage Bonds Due 2027 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			3.68%
Total principal amount outstanding			$ 100	100
3.390 % First Mortgage Bonds Due 2027 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			3.39%
Total principal amount outstanding			$ 35	35
4.650% First Mortgage Bonds Due 2028 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			4.65%
Total principal amount outstanding			$ 425	425
3.800% First Mortgage Bonds Due 2028 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			3.80%
Total principal amount outstanding			$ 300	300
4.900% First Mortgage Bonds Due 2029 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			4.90%
Total principal amount outstanding			$ 500	500
5.070% First Mortgage Bonds Due 2029 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			5.07%
Total principal amount outstanding			$ 50	50
4.600% First Mortgage Bonds Due 2029 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			4.60%
Total principal amount outstanding			$ 600	0
4.700% First Mortgage Bonds Due 2030 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			4.70%
Total principal amount outstanding			$ 700	0
5.170% First Mortgage Bonds Due 2032 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			5.17%
Total principal amount outstanding			$ 95	95
3.600% First Mortgage Bonds Due 2032 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			3.60%
Total principal amount outstanding			$ 350	350
3.180% First Mortgage Bonds Due 2032 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			3.18%
Total principal amount outstanding			$ 100	100
4.625% First Mortgage Bonds Due 2033 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			4.625%
Total principal amount outstanding			$ 700	700
5.800 % First Mortgage Bonds Due 2035 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			5.80%
Total principal amount outstanding			$ 175	175
5.380% First Mortgage Bonds Due 2037 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			5.38%
Total principal amount outstanding			$ 140	140
3.520% First Mortgage Bonds Due 2037 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			3.52%
Total principal amount outstanding			$ 335	335
4.010% First Mortgage Bonds Due 2038 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			4.01%
Total principal amount outstanding			$ 215	215
6.170% First Mortgage Bonds Due 2040 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			6.17%
Total principal amount outstanding			$ 50	50
4.970% First Mortgage Bonds Due 2040 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			4.97%
Total principal amount outstanding			$ 50	50
4.310% First Mortgage Bonds Due 2042 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			4.31%
Total principal amount outstanding			$ 263	263
3.950% First Mortgage Bonds Due 2043 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			3.95%
Total principal amount outstanding			$ 425	425
4.100% First Mortgage Bonds Due 2045 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			4.10%
Total principal amount outstanding			$ 250	250
3.250% First Mortgage Bonds Due 2046 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			3.25%
Total principal amount outstanding			$ 450	450
3.950% First Mortgage Bonds Due 2047 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			3.95%
Total principal amount outstanding			$ 350	350
4.050% First Mortgage Bonds Due 2048 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			4.05%
Total principal amount outstanding			$ 550	550
4.350% First Mortgage Bonds Due 2049 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			4.35%
Total principal amount outstanding			$ 550	550
3.750% First Mortgage Bonds Due 2050 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			3.75%
Total principal amount outstanding			$ 300	300
3.100% First Mortgage Bonds Due 2050 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			3.10%
Total principal amount outstanding			$ 550	550
3.500 First Mortgage Bonds Due 2051 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			3.50%
Total principal amount outstanding			$ 575	575
2.650 First Mortgage Bonds Due 2052 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			2.65%
Total principal amount outstanding			$ 300	300
4.200% First Mortgage Bonds Due 2052 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			4.20%
Total principal amount outstanding			$ 450	450
3.860% First Mortgage Bonds Due 2052 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			3.86%
Total principal amount outstanding			$ 50	50
4.280% First Mortgage Bonds Due 2057 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			4.28%
Total principal amount outstanding			$ 185	185
2.500% First Mortgage Bonds Due 2060 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			2.50%
Total principal amount outstanding			$ 525	525
4.350% First Mortgage Bonds Due 2064 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			4.35%
Total principal amount outstanding			$ 250	250
Variable Rate First Mortgage Bonds Due 2069 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Total principal amount outstanding			$ 76	$ 76
Interest rate at period end			4.32%	5.346%
Variable Rate First Mortgage Bonds Due 2070 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Total principal amount outstanding			$ 134	$ 134
Interest rate at period end			4.483%	5.329%
Variable Rate First Mortgage Bonds Due 2070 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Total principal amount outstanding			$ 127	$ 127
Interest rate at period end			4.551%	5.368%
0.875% Tax Exempt Revenue Bonds Due 2035 | Tax-exempt revenue bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			0.875%
Total principal amount outstanding			$ 35	$ 35
3.350% Tax Exempt Revenue Bonds Due 2049 | Tax-exempt revenue bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest Rate (%)			3.35%
Total principal amount outstanding			$ 75	75
3.528% Securitization Bonds | Securitization bonds | Consumers Energy Company
Debt Instrument [Line Items]
Total principal amount outstanding			$ 112	$ 141
Weighted average interest rate			3.528%	3.421%
5.322% Securitization Bonds | Securitization bonds | Consumers Energy Company
Debt Instrument [Line Items]
Total principal amount outstanding			$ 588	$ 646
Weighted average interest rate			5.322%	5.342%
Variable Rate First Mortgage Bonds | First mortgage bonds | Consumers Energy Company | SOFR
Debt Instrument [Line Items]
Basis spread on variable rate			0.038%
CMS Energy
Debt Instrument [Line Items]
Total principal amount outstanding			$ 5,025	$ 4,785
Current amounts			(740)	(250)
Long-term debt - related parties principal amount outstanding			(490)
Long-term debt			4,226	4,471
CMS Energy | Consumers Energy Company
Debt Instrument [Line Items]
Total principal amount outstanding			11,370	10,863
CMS Energy | Senior notes
Debt Instrument [Line Items]
Total principal amount outstanding			1,725	1,975
CMS Energy | Junior subordinated notes
Debt Instrument [Line Items]
Total principal amount outstanding			2,010	2,010
CMS Energy | Term loan facility
Debt Instrument [Line Items]
Total principal amount outstanding			$ 490	0
CMS Energy | 3.875% Senior Notes Due 2024 | Senior notes
Debt Instrument [Line Items]
Interest Rate (%)			3.875%
Total principal amount outstanding			$ 0	250
CMS Energy | 3.600% Senior Notes Due 2025 | Senior notes
Debt Instrument [Line Items]
Interest Rate (%)			3.60%
Total principal amount outstanding			$ 250	250
CMS Energy | 3.000% Senior Notes Due 2026 | Senior notes
Debt Instrument [Line Items]
Interest Rate (%)			3.00%
Total principal amount outstanding			$ 300	300
CMS Energy | 2.950% Senior Notes Due 2027 | Senior notes
Debt Instrument [Line Items]
Interest Rate (%)			2.95%
Total principal amount outstanding			$ 275	275
CMS Energy | 3.450% Senior Notes Due 2027 | Senior notes
Debt Instrument [Line Items]
Interest Rate (%)			3.45%
Total principal amount outstanding			$ 350	350
CMS Energy | 4.700% Senior Notes Due 2043 | Senior notes
Debt Instrument [Line Items]
Interest Rate (%)			4.70%
Total principal amount outstanding			$ 250	250
CMS Energy | 4.875% Senior Notes Due 2044 | Senior notes
Debt Instrument [Line Items]
Interest Rate (%)			4.875%
Total principal amount outstanding			$ 300	300
CMS Energy | 3.375% Convertible Senior Notes Due 2028 | Convertible debt
Debt Instrument [Line Items]
Interest Rate (%)			3.375%
Total principal amount outstanding			$ 800	800
CMS Energy | 4.750% Junior Subordinated Notes Due 2050 | Junior subordinated notes
Debt Instrument [Line Items]
Interest Rate (%)			4.75%
Total principal amount outstanding			$ 500	500
CMS Energy | 4.750% Junior Subordinated Notes Due 2050 | Junior subordinated notes | US Treasury (UST) Interest Rate | Forecast
Debt Instrument [Line Items]
Basis spread on variable rate		4.116%
CMS Energy | 3.750% Junior Subordinated Notes Due 2050 | Junior subordinated notes
Debt Instrument [Line Items]
Interest Rate (%)			3.75%
Total principal amount outstanding			$ 400	400
CMS Energy | 3.750% Junior Subordinated Notes Due 2050 | Junior subordinated notes | US Treasury (UST) Interest Rate | Forecast
Debt Instrument [Line Items]
Basis spread on variable rate	2.90%
CMS Energy | 5.625% Junior Subordinated Notes Due 2078 | Junior subordinated notes
Debt Instrument [Line Items]
Interest Rate (%)			5.625%
Total principal amount outstanding			$ 200	200
CMS Energy | 5.875% Junior Subordinated Notes Due 2078 | Junior subordinated notes
Debt Instrument [Line Items]
Interest Rate (%)			5.875%
Total principal amount outstanding			$ 280	280
CMS Energy | 5.875% Junior Subordinated Notes Due 2079 | Junior subordinated notes
Debt Instrument [Line Items]
Interest Rate (%)			5.875%
Total principal amount outstanding			$ 630	630
CMS Energy | 5.245% Delayed Draw Unsecured Term Loan Credit Facility Due 2025 | Term loan facility
Debt Instrument [Line Items]
Total principal amount outstanding			90	0
Long-term debt - related parties principal amount outstanding			$ (90)
Basis spread on variable rate			0.90%
Interest rate at period end			5.245%
CMS Energy | 5.028% Delayed Draw Unsecured Term Loan Credit Facility Due 2025 | Term loan facility
Debt Instrument [Line Items]
Total principal amount outstanding			$ 400	0
Long-term debt - related parties principal amount outstanding			$ (400)
Basis spread on variable rate			0.85%
Interest rate at period end			5.403%
CMS Energy | 3.375% Convertible Senior Notes Due 2028 | Convertible debt
Debt Instrument [Line Items]
Conversion price (in dollars per share)			$ 73.93
Unamortized issuance costs			$ 9
NorthStar Clean Energy, Including Subsidiaries | Revolving Credit Facilities May 7, 2027
Debt Instrument [Line Items]
Basis spread on variable rate			1.75%
Interest rate at period end			6.097%
Interest rate adjustment			0.05%
NorthStar Clean Energy, Including Subsidiaries | Revolving Credit Facility Due 2027 | Revolving Credit Facility
Debt Instrument [Line Items]
Total principal amount outstanding			$ 150	$ 0