Financings and Capitalization (Summary of Long-Term Debt) (Details) - USD ($) $ in Millions			12 Months Ended
	Dec. 01, 2030	Jun. 01, 2030	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Total principal amount outstanding			$ 15,648	$ 14,362
Current amounts			(975)	(1,090)
Long-term debt - related parties principal amount outstanding			(3,556)
Unamortized discounts			(30)	(30)
Unamortized issuance costs			(135)	(120)
Long-term debt			14,508	13,122
Consumers Energy Company
Debt Instrument [Line Items]
Total principal amount outstanding			11,294	10,277
Current amounts			(725)	(991)
Long-term debt - related parties principal amount outstanding			(2,671)
Unamortized discounts			(28)	(27)
Unamortized issuance costs			(73)	(67)
Long-term debt			10,037	9,192
Consumers Energy Company | Related Party
Debt Instrument [Line Items]
Long-term debt - related parties principal amount outstanding			(431)
Long-term debt			424	0
First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Total principal amount outstanding			10,397	8,997
First mortgage bonds | Consumers Energy Company | Related Party
Debt Instrument [Line Items]
Long-term debt - related parties principal amount outstanding			(431)
Unamortized discounts			(3)
Unamortized issuance costs			(4)
Long-term debt			424
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			$ 787	170
0.350% First Mortgage Bonds Due June 2023 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest rate			0.35%
Total principal amount outstanding			$ 0	300
3.375% First Mortgage Bonds Due 2023 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest rate			3.375%
Total principal amount outstanding			$ 0	325
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			$ 250	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			$ 52	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	0
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	0
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	0
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	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	0
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	0
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	0
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
3.750% First Mortgage Bonds Due 2050 | First mortgage bonds | Consumers Energy Company | Related Party
Debt Instrument [Line Items]
Long-term debt - related parties principal amount outstanding			$ (23)
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
3.100% First Mortgage Bonds Due 2050 | First mortgage bonds | Consumers Energy Company | Related Party
Debt Instrument [Line Items]
Long-term debt - related parties principal amount outstanding			$ (52)
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
3.500 First Mortgage Bonds Due 2051 | First mortgage bonds | Consumers Energy Company | Related Party
Debt Instrument [Line Items]
Long-term debt - related parties principal amount outstanding			$ (27)
2.650% 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
2.650% First Mortgage Bonds Due 2060 | First mortgage bonds | Consumers Energy Company | Related Party
Debt Instrument [Line Items]
Long-term debt - related parties principal amount outstanding			$ (163)
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 2052 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest rate			2.65%
Total principal amount outstanding			$ 300	300
2.500 First Mortgage Bonds Due 2052 | First mortgage bonds | Consumers Energy Company | Related Party
Debt Instrument [Line Items]
Long-term debt - related parties principal amount outstanding			$ (106)
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			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			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			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
1.800% Tax Exempt Revenue Bonds Due 2049 | Tax-exempt revenue bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest rate			1.80%
Total principal amount outstanding			$ 75	75
3.421% Securitization Bonds | Securitization bonds | Consumers Energy Company
Debt Instrument [Line Items]
Total principal amount outstanding			$ 141	$ 170
Weighted average interest rate			3.421%	3.343%
- Securitization Bonds Due - | Securitization bonds | Consumers Energy Company
Debt Instrument [Line Items]
Total principal amount outstanding			$ 646	$ 0
Weighted average interest rate			5.342%
Term Loan Facility Due 2024 | Term loan facility | Consumers Energy Company
Debt Instrument [Line Items]
Total principal amount outstanding			$ 0	$ 1,000
Variable Rate First Mortgage Bonds | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Interest rate at period end				0.00%
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			$ 4,785	$ 3,985
Current amounts			(250)	0
Long-term debt - related parties principal amount outstanding			(800)
Long-term debt			4,471	3,930
CMS Energy | Consumers Energy Company
Debt Instrument [Line Items]
Total principal amount outstanding			10,863	10,277
CMS Energy | Senior notes
Debt Instrument [Line Items]
Total principal amount outstanding			1,975	1,975
CMS Energy | Convertible debt
Debt Instrument [Line Items]
Total principal amount outstanding			800	0
CMS Energy | Junior subordinated notes
Debt Instrument [Line Items]
Total principal amount outstanding			$ 2,010	2,010
CMS Energy | 3.875% Senior Notes Due 2024 | Senior notes
Debt Instrument [Line Items]
Interest rate			3.875%
Total principal amount outstanding			$ 250	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	0
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 | Forecast | US Treasury (UST) Interest Rate
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 | Forecast | US Treasury (UST) Interest Rate
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
NorthStar Clean Energy, Including Subsidiaries
Debt Instrument [Line Items]
Long-term debt - related parties principal amount outstanding			(85)
NorthStar Clean Energy, Including Subsidiaries | Term Loan Facility Due 2023 | Term loan facility
Debt Instrument [Line Items]
Total principal amount outstanding			0	$ 100
Long-term debt - related parties principal amount outstanding			$ (85)