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Financings and Capitalization (Summary of Long-Term Debt) (Details) - USD ($) $ in Millions |  |  | 1 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Dec. 01, 2030 | Jun. 01, 2030 | Oct. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Debt Instrument [Line Items] |  |  |  |  |
Total principal amount outstanding |  |  |  | $ 12,568 | $ 12,467
Current amounts |  |  |  | (373) | (571)
Unamortized discounts |  |  |  | (31) | (33)
Unamortized issuance costs |  |  |  | (118) | (119)
Long-term debt |  |  |  | 12,046 | 11,744
Consumers Energy Company |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total principal amount outstanding |  |  |  | 8,505 | 8,197
Current amounts |  |  |  | (365) | (364)
Unamortized discounts |  |  |  | (28) | (29)
Unamortized issuance costs |  |  |  | (62) | (62)
Long-term debt |  |  |  | 8,050 | 7,742
First Mortgage Bonds | Consumers Energy Company |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total principal amount outstanding |  |  |  | $ 8,197 | 7,897
First Mortgage Bonds | Consumers Energy Company | 0.350% First Mortgage Bonds Due 2023 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 0.35% |
Total principal amount outstanding |  |  |  | $ 300 | 300
First Mortgage Bonds | Consumers Energy Company | 3.375% First Mortgage Bonds Due 2023 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.375% |
Total principal amount outstanding |  |  |  | $ 325 | 325
First Mortgage Bonds | Consumers Energy Company | 3.125% First Mortgage Bonds Due 2024 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.125% |
Total principal amount outstanding |  |  |  | $ 250 | 250
First Mortgage Bonds | Consumers Energy Company | 3.190% First Mortgage Bonds Due 2024 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.19% |
Total principal amount outstanding |  |  |  | $ 52 | 52
First Mortgage Bonds | Consumers Energy Company | 3.680% First Mortgage Bonds Due 2027 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.68% |
Total principal amount outstanding |  |  |  | $ 100 | 100
First Mortgage Bonds | Consumers Energy Company | 3.390 % First Mortgage Bonds Due 2027 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.39% |
Total principal amount outstanding |  |  |  | $ 35 | 35
First Mortgage Bonds | Consumers Energy Company | 3.800% First Mortgage Bonds Due 2028 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.80% |
Total principal amount outstanding |  |  |  | $ 300 | 300
First Mortgage Bonds | Consumers Energy Company | 3.180% First Mortgage Bonds Due 2032 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.18% |
Total principal amount outstanding |  |  |  | $ 100 | 100
First Mortgage Bonds | Consumers Energy Company | 5.800 % First Mortgage Bonds Due 2035 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 5.80% |
Total principal amount outstanding |  |  |  | $ 175 | 175
First Mortgage Bonds | Consumers Energy Company | 3.520% First Mortgage Bonds Due 2037 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.52% |
Total principal amount outstanding |  |  |  | $ 335 | 335
First Mortgage Bonds | Consumers Energy Company | 4.010% First Mortgage Bonds Due 2038 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 4.01% |
Total principal amount outstanding |  |  |  | $ 215 | 215
First Mortgage Bonds | Consumers Energy Company | 6.170% First Mortgage Bonds Due 2040 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 6.17% |
Total principal amount outstanding |  |  |  | $ 50 | 50
First Mortgage Bonds | Consumers Energy Company | 4.970% First Mortgage Bonds Due 2040 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 4.97% |
Total principal amount outstanding |  |  |  | $ 50 | 50
First Mortgage Bonds | Consumers Energy Company | 4.310% First Mortgage Bonds Due 2042 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 4.31% |
Total principal amount outstanding |  |  |  | $ 263 | 263
First Mortgage Bonds | Consumers Energy Company | 3.950% First Mortgage Bonds Due 2043 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.95% |
Total principal amount outstanding |  |  |  | $ 425 | 425
First Mortgage Bonds | Consumers Energy Company | 4.100% First Mortgage Bonds Due 2045 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 4.10% |
Total principal amount outstanding |  |  |  | $ 250 | 250
First Mortgage Bonds | Consumers Energy Company | 3.250% First Mortgage Bonds Due 2046 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.25% |
Total principal amount outstanding |  |  |  | $ 450 | 450
First Mortgage Bonds | Consumers Energy Company | 3.950% First Mortgage Bonds Due 2047 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.95% |
Total principal amount outstanding |  |  |  | $ 350 | 350
First Mortgage Bonds | Consumers Energy Company | 4.050% First Mortgage Bonds Due 2048 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 4.05% |
Total principal amount outstanding |  |  |  | $ 550 | 550
First Mortgage Bonds | Consumers Energy Company | 4.350% First Mortgage Bonds Due 2049 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 4.35% |
Total principal amount outstanding |  |  |  | $ 550 | 550
First Mortgage Bonds | Consumers Energy Company | 3.750% First Mortgage Bonds Due 2050 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.75% |
Total principal amount outstanding |  |  |  | $ 300 | 300
First Mortgage Bonds | Consumers Energy Company | 3.100% First Mortgage Bonds Due 2050 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.10% |
Total principal amount outstanding |  |  |  | $ 550 | 550
First Mortgage Bonds | Consumers Energy Company | 3.500% First Mortgage Bonds Due 2051 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.50% |
Total principal amount outstanding |  |  |  | $ 575 | 575
First Mortgage Bonds | Consumers Energy Company | 2.650% First Mortgage Bonds Due 2052 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 2.65% |
Total principal amount outstanding |  |  |  | $ 300 | 0
First Mortgage Bonds | Consumers Energy Company | 3.860% First Mortgage Bonds Due 2052 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.86% |
Total principal amount outstanding |  |  |  | $ 50 | 50
First Mortgage Bonds | Consumers Energy Company | 4.280% First Mortgage Bonds Due 2057 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 4.28% |
Total principal amount outstanding |  |  |  | $ 185 | 185
First Mortgage Bonds | Consumers Energy Company | 2.500% First Mortgage Bonds Due 2060 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 2.50% |
Total principal amount outstanding |  |  |  | $ 525 | 525
First Mortgage Bonds | Consumers Energy Company | 4.350% First Mortgage Bonds Due 2064 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 4.35% |
Total principal amount outstanding |  |  |  | $ 250 | 250
First Mortgage Bonds | Consumers Energy Company | Variable Rate First Mortgage Bonds Due 2069 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total principal amount outstanding |  |  |  | 76 | 76
First Mortgage Bonds | Consumers Energy Company | Variable Rate First Mortgage Bonds Due 2070 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total principal amount outstanding |  |  |  | 134 | 134
First Mortgage Bonds | Consumers Energy Company | Variable Rate First Mortgage Bonds Due 2070 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total principal amount outstanding |  |  |  | $ 127 | $ 127
First Mortgage Bonds | Consumers Energy Company | Variable Rate First Mortgage Bonds |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Basis spread on variable rate |  |  |  | 0.30% |
Interest rate at period end |  |  |  | 0.00% | 0.00%
Tax Exempt Revenue Bonds | Consumers Energy Company |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total principal amount outstanding |  |  |  | $ 110 | $ 75
Tax Exempt Revenue Bonds | Consumers Energy Company | 0.875% Tax Exempt Revenue Bonds Due 2035 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 0.875% |
Total principal amount outstanding |  |  |  | $ 35 | 0
Tax Exempt Revenue Bonds | Consumers Energy Company | 1.800% Tax Exempt Revenue Bonds Due 2049 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 1.80% |
Total principal amount outstanding |  |  |  | $ 75 | $ 75
Securitization bonds | Consumers Energy Company | Securitization Bonds |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Weighted average interest rate |  |  |  | 3.29% | 3.25%
Total principal amount outstanding |  |  |  | $ 198 | $ 225
CMS Energy |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total principal amount outstanding |  |  |  | 3,985 | 4,185
Long-term debt |  |  |  | 3,928 | 3,926
CMS Energy | Senior notes |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total principal amount outstanding |  |  |  | $ 1,975 | 1,975
CMS Energy | Senior notes | 3.875% Senior Notes Due 2024 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.875% |
Total principal amount outstanding |  |  |  | $ 250 | 250
CMS Energy | Senior notes | 3.600% Senior Notes Due 2025 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.60% |
Total principal amount outstanding |  |  |  | $ 250 | 250
CMS Energy | Senior notes | 3.000% Senior Notes Due 2026 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.00% |
Total principal amount outstanding |  |  |  | $ 300 | 300
CMS Energy | Senior notes | 2.950% Senior Notes Due 2027 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 2.95% |
Total principal amount outstanding |  |  |  | $ 275 | 275
CMS Energy | Senior notes | 3.450% Senior Notes Due 2027 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.45% |
Total principal amount outstanding |  |  |  | $ 350 | 350
CMS Energy | Senior notes | 4.700% Senior Notes Due 2043 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 4.70% |
Total principal amount outstanding |  |  |  | $ 250 | 250
CMS Energy | Senior notes | 4.875% Senior Notes Due 2044 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 4.875% |
Total principal amount outstanding |  |  |  | $ 300 | 300
CMS Energy | Term loan facility | Term Loan Facility Due 2021 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total principal amount outstanding |  |  |  | 0 | 200
CMS Energy | Junior subordinated notes |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total principal amount outstanding |  |  |  | $ 2,010 | 2,010
CMS Energy | Junior subordinated notes | 4.750% Junior Subordinated Notes Due 2050 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 4.75% |
Total principal amount outstanding |  |  |  | $ 500 | 500
CMS Energy | Junior subordinated notes | 3.750% Junior Subordinated Notes Due 2050 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 3.75% |
Total principal amount outstanding |  |  |  | $ 400 | 400
CMS Energy | Junior subordinated notes | 5.625% Junior Subordinated Notes Due 2078 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 5.625% |
Total principal amount outstanding |  |  |  | $ 200 | 200
CMS Energy | Junior subordinated notes | 5.875% Junior Subordinated Notes Due 2078 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 5.875% |
Total principal amount outstanding |  |  |  | $ 280 | 280
CMS Energy | Junior subordinated notes | 5.875% Junior Subordinated Notes Due 2079 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate |  |  |  | 5.875% |
Total principal amount outstanding |  |  |  | $ 630 | 630
CMS Enterprises Including Subsidiaries | Term loan facility | Term Loan Facility Due 2025 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total principal amount outstanding |  |  |  | $ 78 | $ 85
Basis spread on variable rate |  |  |  | 1.50% |
Interest rate at period end |  |  |  | 1.724% | 1.754%
Fixed interest rate |  |  |  | 4.702% |
Forecast | CMS Energy | Junior subordinated notes | 4.750% Junior Subordinated Notes Due 2050 | US Treasury (UST) Interest Rate |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Basis spread on variable rate |  | 4.116% |  |  |
Forecast | CMS Energy | Junior subordinated notes | 3.750% Junior Subordinated Notes Due 2050 | US Treasury (UST) Interest Rate |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Basis spread on variable rate | 2.90% |  |  |  |
Forecast | CMS Enterprises Including Subsidiaries | Term loan facility | Term Loan Facility Due 2025 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Basis spread on variable rate |  |  | 1.75% |  |
Fixed interest rate |  |  | 4.952% |  |

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