Financial Instruments (Schedule of Carrying Amounts and Fair Values of Financial Instruments) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Liabilities
Current accounts receivable and notes receivable	$ 3	$ 4
Current portion of long-term debt	704	1,200
Current portion of long-term payables	1
Carrying Amount
Assets
Long-term receivables	8	9
Liabilities
Long-term debt	16,852	16,386
Long-term payables	8	9
Fair Value
Assets
Long-term receivables	7	8
Liabilities
Long-term debt	15,493	14,876
Long-term payables	8	9
Consumers Energy Company
Liabilities
Current accounts receivable and notes receivable	3	4
Current portion of long-term debt	454	452
Consumers Energy Company | Related Party
Liabilities
Notes receivable	7	7
Consumers Energy Company | Carrying Amount
Assets
Long-term receivables	8	9
Notes receivable related party	93	94
Liabilities
Long-term payables	3	4
Consumers Energy Company | Carrying Amount | Nonrelated Party
Liabilities
Long-term debt	11,230	11,270
Consumers Energy Company | Carrying Amount | Related Party
Liabilities
Long-term debt	823	823
Consumers Energy Company | Fair Value
Assets
Long-term receivables	7	8
Notes receivable related party	93	94
Liabilities
Long-term payables	3	4
Consumers Energy Company | Fair Value | Nonrelated Party
Liabilities
Long-term debt	10,007	9,940
Consumers Energy Company | Fair Value | Related Party
Liabilities
Long-term debt	550	549
Level 1 | Fair Value
Assets
Long-term receivables	0	0
Liabilities
Long-term debt	1,971	1,018
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	11,598	11,952
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	8,083	8,034
Level 2 | Consumers Energy Company | Fair Value | Related Party
Liabilities
Long-term debt	550	549
Level 3 | Fair Value
Assets
Long-term receivables	7	8
Liabilities
Long-term debt	1,924	1,906
Long-term payables	8	9
Level 3 | Consumers Energy Company | Fair Value
Assets
Long-term receivables	7	8
Notes receivable related party	93	94
Liabilities
Long-term payables	3	4
Level 3 | Consumers Energy Company | Fair Value | Nonrelated Party
Liabilities
Long-term debt	1,924	1,906
Level 3 | Consumers Energy Company | Fair Value | Related Party
Liabilities
Long-term debt	$ 0	$ 0