Leases and Palisades Financing - Lessor Leases Narrative (Details) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($)
Sales-type and Direct Financing Leases, Lease Receivable, Fiscal Year Maturity [Abstract]
Minimum rental payments to be received 2025 and thereafter	$ 10
Unearned income	5
Lease receivables	5
Maximum
Sales-type and Direct Financing Leases, Lease Receivable, Fiscal Year Maturity [Abstract]
Minimum rental payments to be received 2020	1
Minimum annual rental payments to be received in 2021	1
Minimum annual rental payments to be received in 2022	1
Minimum annual rental payments to be received in 2023	1
Minimum rental payments to be received in 2024	1
Consumers Energy Company
Sales-type and Direct Financing Leases, Lease Receivable, Fiscal Year Maturity [Abstract]
Minimum rental payments to be received 2020	1
Minimum annual rental payments to be received in 2021	1
Minimum annual rental payments to be received in 2022	1
Minimum annual rental payments to be received in 2023	1
Minimum rental payments to be received in 2024	1
Minimum rental payments to be received 2025 and thereafter	19
Unearned income	14
Lease receivables	10
Power Sales Agreement
Lessor, Lease, Description [Line Items]
Leasing income	174
Variable lease income	$ 119
CMS Energy Subsidiary \| Natural Gas Transportation Agreement \| Consumers Energy Company
Lessor, Lease, Description [Line Items]
Direct financing lease term	20 years

Term of lessor's direct financing lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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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.

+ References

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Amount of operating lease income from variable lease payments paid and payable to lessor, excluding amount 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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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 latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest statement of financial position date.

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases in fourth fiscal year following 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 undiscounted cash flows to be received by lessor for sales-type and direct financing leases in the next fiscal year following latest fiscal year. Excludes interim and annual periods when interim periods are reported on rolling approach, from latest statement of financial position date.

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases after fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest statement of financial position date.

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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 latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest statement of financial position date.

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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 latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest statement of financial position date.

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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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