Leases And Palisades Financing (Schedule of Future Minimum Lease Payments for Leases) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Leases [Line Items]
Capital and Financing Leases, Non-current portion	$ 91	$ 110
Consumers Energy Company [Member]
Leases [Line Items]
Capital and Financing Leases, Non-current portion	91	$ 110
Operating Leases, 2018	15
Operating Leases, 2019	9
Operating Leases, 2020	9
Operating Leases, 2021	9
Operating Leases, 2022	4
Operating Leases, 2023 and thereafter	7
Operating Leases, Total minimum lease payments	53
Consumers Energy Company [Member] \| Capital Leases [Member]
Leases [Line Items]
Capital and Financing Leases, 2018	15
Capital and Financing Leases, 2019	15
Capital and Financing Leases, 2020	12
Capital and Financing Leases, 2021	12
Capital and Financing Leases, 2022	8
Capital and Financing Leases, 2023 and thereafter	21
Capital and Financing Leases, Total minimum lease payments	83
Capital and Financing Leases, Less imputed interest	25
Capital and Financing Leases, Present value of net minimum lease payments	58
Capital and Financing Leases, Less current portion	9
Capital and Financing Leases, Non-current portion	49
Consumers Energy Company [Member] \| Financing Leases [Member]
Leases [Line Items]
Capital and Financing Leases, 2018	16
Capital and Financing Leases, 2019	15
Capital and Financing Leases, 2020	14
Capital and Financing Leases, 2021	14
Capital and Financing Leases, 2022	3
Capital and Financing Leases, Total minimum lease payments	62
Capital and Financing Leases, Less imputed interest	7
Capital and Financing Leases, Present value of net minimum lease payments	55
Capital and Financing Leases, Less current portion	13
Capital and Financing Leases, Non-current portion	$ 42

Leases [Line Items]

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Amount of capital lease obligation due within one year or the normal operating cycle, if longer.

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Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal, through the balance sheet date and due to be paid more than one year (or one operating cycle, if longer) after the balance sheet date.

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Amount of minimum lease payments for capital leases.

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Amount of minimum lease payments for capital leases due in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of minimum lease payments for capital leases due in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of minimum lease payments for capital leases due in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of minimum lease payments for capital leases due after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount necessary to reduce net minimum lease payments to present value for capital leases.

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Present value of minimum lease payments for capital leases net of executory costs, including amounts paid by the lessee to the lessor for insurance, maintenance and taxes.

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Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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