Contingencies and Commitments (Schedule of Remediation and Other Response Activity Costs by Year) (Details) $ in Millions	Dec. 31, 2024 USD ($)
Bay Harbor
Site Contingency [Line Items]
2025	$ 4
2026	4
2027	4
2028	4
2029	4
Consumers Energy Company \| MGP sites
Site Contingency [Line Items]
2025	3
2026	7
2027	9
2028	24
2029	$ 7

Undiscounted amount of accrual for environmental loss contingency to be paid in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Undiscounted amount of accrual for environmental loss contingency to be paid in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Undiscounted amount of accrual for environmental loss contingency to be paid in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Undiscounted amount of accrual for environmental loss contingency to be paid in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Undiscounted amount of accrual for environmental loss contingency to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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