Financial Instruments (Schedule of Carrying Amounts and Fair Values of Financial Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Liabilities
Current accounts receivable and notes receivable	$ 4	$ 6
Current portion of long-term debt	1,192	975
Current portion of long-term payables	2	2
Carrying Amount
Assets
Long-term receivables	9	11
Liabilities
Long-term debt	16,386	15,483
Long-term payables	9	11
Fair Value
Assets
Long-term receivables	8	11
Liabilities
Long-term debt	14,876	14,305
Long-term payables	9	11
Consumers Energy Company
Liabilities
Current accounts receivable and notes receivable	4	6
Current portion of long-term debt	452	725
Consumers Energy Company | Related Party
Liabilities
Notes receivable	7	7
Consumers Energy Company | Carrying Amount
Assets
Long-term receivables	9	11
Notes receivable related party	94	97
Liabilities
Long-term payables	4	5
Consumers Energy Company | Carrying Amount | Nonrelated Party
Liabilities
Long-term debt	11,270	10,762
Consumers Energy Company | Carrying Amount | Related Party
Liabilities
Long-term debt	823	424
Consumers Energy Company | Fair Value
Assets
Long-term receivables	8	11
Notes receivable related party	94	97
Liabilities
Long-term payables	4	5
Consumers Energy Company | Fair Value | Nonrelated Party
Liabilities
Long-term debt	9,940	9,757
Consumers Energy Company | Fair Value | Related Party
Liabilities
Long-term debt	549	303
Level 1 | Fair Value
Assets
Long-term receivables	0	0
Liabilities
Long-term debt	1,018	1,103
Long-term payables	0	0
Level 1 | Consumers Energy Company | Fair Value
Assets
Long-term receivables	0	0
Notes receivable related party	0	0
Liabilities
Long-term payables	0	0
Level 1 | Consumers Energy Company | Fair Value | Nonrelated Party
Liabilities
Long-term debt	0	0
Level 1 | Consumers Energy Company | Fair Value | Related Party
Liabilities
Long-term debt	0	0
Level 2 | Fair Value
Assets
Long-term receivables	0	0
Liabilities
Long-term debt	11,952	11,186
Long-term payables	0	0
Level 2 | Consumers Energy Company | Fair Value
Assets
Long-term receivables	0	0
Notes receivable related party	0	0
Liabilities
Long-term payables	0	0
Level 2 | Consumers Energy Company | Fair Value | Nonrelated Party
Liabilities
Long-term debt	8,034	7,741
Level 2 | Consumers Energy Company | Fair Value | Related Party
Liabilities
Long-term debt	549	303
Level 3 | Fair Value
Assets
Long-term receivables	8	11
Liabilities
Long-term debt	1,906	2,016
Long-term payables	9	11
Level 3 | Consumers Energy Company | Fair Value
Assets
Long-term receivables	8	11
Notes receivable related party	94	97
Liabilities
Long-term payables	4	5
Level 3 | Consumers Energy Company | Fair Value | Nonrelated Party
Liabilities
Long-term debt	1,906	2,016
Level 3 | Consumers Energy Company | Fair Value | Related Party
Liabilities
Long-term debt	$ 0	$ 0