v3.26.1
Financial Instruments (Schedule of Carrying Amounts and Fair Values of Financial Instruments) (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Liabilities    
Current accounts receivable and notes receivable $ 2 $ 3
Current portion of long-term debt 864 950
Current portion of long-term payables 1 2
Carrying Amount    
Assets    
Long-term receivables 6 7
Liabilities    
Long-term debt 19,036 18,757
Long-term payables 6 7
Fair Value    
Assets    
Long-term receivables 5 6
Liabilities    
Long-term debt 18,438 17,645
Long-term payables 6 7
Consumers Energy Company    
Liabilities    
Current accounts receivable and notes receivable 2 3
Current portion of long-term debt 461 573
Consumers Energy Company | Related Party    
Liabilities    
Notes receivable 7 7
Consumers Energy Company | Carrying Amount    
Assets    
Long-term receivables 6 7
Notes receivable related party 89 90
Liabilities    
Long-term payables 1 2
Consumers Energy Company | Carrying Amount | Nonrelated Party    
Liabilities    
Long-term debt 12,769 12,097
Consumers Energy Company | Carrying Amount | Related Party    
Liabilities    
Long-term debt 1,005 1,005
Consumers Energy Company | Fair Value    
Assets    
Long-term receivables 5 6
Notes receivable related party 89 90
Liabilities    
Long-term payables 1 2
Consumers Energy Company | Fair Value | Nonrelated Party    
Liabilities    
Long-term debt 12,209 11,031
Consumers Energy Company | Fair Value | Related Party    
Liabilities    
Long-term debt 649 657
Level 1 | Fair Value    
Assets    
Long-term receivables 0 0
Liabilities    
Long-term debt 1,984 2,042
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 14,643 13,663
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 10,398 9,091
Level 2 | Consumers Energy Company | Fair Value | Related Party    
Liabilities    
Long-term debt 649 657
Level 3 | Fair Value    
Assets    
Long-term receivables 5 6
Liabilities    
Long-term debt 1,811 1,940
Long-term payables 6 7
Level 3 | Consumers Energy Company | Fair Value    
Assets    
Long-term receivables 5 6
Notes receivable related party 89 90
Liabilities    
Long-term payables 1 2
Level 3 | Consumers Energy Company | Fair Value | Nonrelated Party    
Liabilities    
Long-term debt 1,811 1,940
Level 3 | Consumers Energy Company | Fair Value | Related Party    
Liabilities    
Long-term debt $ 0 $ 0