Financial Instruments (Schedule of Carrying Amounts and Fair Values of Financial Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Liabilities
Current accounts receivable and notes receivable	$ 6	$ 7
Current portion of long-term debt	975	1,090
Current portion of long-term payables		2
Carrying Amount
Assets
Long-term receivables	11	14
Liabilities
Long-term debt	15,483	14,212
Long-term payables	11	9
Fair Value
Assets
Long-term receivables	11	14
Liabilities
Long-term debt	14,305	12,384
Long-term payables	11	7
Consumers Energy Company
Liabilities
Current accounts receivable and notes receivable	6	7
Current portion of long-term debt	725	991
Consumers Energy Company | Related Party
Liabilities
Current portion of notes receivable, related party	7	7
Consumers Energy Company | Carrying Amount
Assets
Long-term receivables	11	14
Notes receivable related party	97	101
Liabilities
Long-term payables	5	0
Consumers Energy Company | Carrying Amount | Nonrelated Party
Liabilities
Long-term debt	10,762	10,183
Consumers Energy Company | Carrying Amount | Related Party
Liabilities
Long-term debt	424	0
Consumers Energy Company | Fair Value
Assets
Long-term receivables	11	14
Notes receivable related party	97	101
Liabilities
Long-term payables	5	0
Consumers Energy Company | Fair Value | Nonrelated Party
Liabilities
Long-term debt	9,757	8,728
Consumers Energy Company | Fair Value | Related Party
Liabilities
Long-term debt	303	0
Level 1 | Fair Value
Assets
Long-term receivables	0	0
Liabilities
Long-term debt	1,103	987
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	11,186	8,741
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	7,741	6,172
Level 2 | Consumers Energy Company | Fair Value | Related Party
Liabilities
Long-term debt	303	0
Level 3 | Fair Value
Assets
Long-term receivables	11	14
Liabilities
Long-term debt	2,016	2,656
Long-term payables	11	7
Level 3 | Consumers Energy Company | Fair Value
Assets
Long-term receivables	11	14
Notes receivable related party	97	101
Liabilities
Long-term payables	5	0
Level 3 | Consumers Energy Company | Fair Value | Nonrelated Party
Liabilities
Long-term debt	2,016	2,556
Level 3 | Consumers Energy Company | Fair Value | Related Party
Liabilities
Long-term debt	$ 0	$ 0