Leases (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
Lessor, Lease, Description [Line Items]
Payment to be received	$ 18
Consumers Energy Company
Sales-type and Direct Financing Leases, Lease Receivable, Fiscal Year Maturity [Abstract]
Minimum rental payments to be received in year one	1
Minimum annual rental payments to be received in year two	1
Minimum annual rental payments to be received in year three	1
Minimum annual rental payments to be received in year four	1
Minimum rental payments to be received in year five	1
Minimum rental payments to be received thereafter	6
Lease receivables	5
Unearned income	5
Power Sales Agreement
Lessor, Lease, Description [Line Items]
Leasing income	149	$ 105
Variable lease income	$ 105	$ 61

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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Amount of lease payment to be received by lessor for operating lease 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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Amount of operating lease income from lease payments and variable lease payments paid and payable to lessor. Includes, but is not limited to, variable lease payments not included in measurement of lease receivable.

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Present value of lease payments not yet received by lessor and amount expected to be derived from underlying asset, following end of lease term guaranteed by lessee or other third party unrelated to lessor, from sales-type and direct financing leases.

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases 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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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases 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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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases 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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Amount of undiscounted lease receivable in excess of discounted receivable for sales-type and direct financing leases.

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