Leases - Assets and Liabilities of Lessee (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Operating leases
Right-of-use assets	$ 54
Lease liabilities
Current lease liabilities	10
Noncurrent lease liabilities	44
Finance leases
Right-of-use assets	78
Lease liabilities
Current lease liabilities	8
Non-current lease liabilities	$ 65
Weighted-average remaining lease term (in years)
Operating leases	14 years
Finance leases	12 years
Weighted-average discount rate
Operating leases	3.70%
Finance leases	2.00%
Related party lease liability	$ 6	$ 10
Consumers Energy Company
Operating leases
Right-of-use assets	46
Lease liabilities
Current lease liabilities	8
Noncurrent lease liabilities	37
Finance leases
Right-of-use assets	78
Lease liabilities
Current lease liabilities	8
Non-current lease liabilities	$ 65
Weighted-average remaining lease term (in years)
Operating leases	13 years
Finance leases	12 years
Weighted-average discount rate
Operating leases	3.60%
Finance leases	2.00%
Related party lease liability	$ 11	$ 14
Related Party Lease
Weighted-average discount rate
Related party lease liability	25
Related Party Lease \| Consumers Energy Company
Weighted-average discount rate
Related party lease liability	25
Maximum \| Related Party Lease
Weighted-average discount rate
Related party lease liability	1
Maximum \| Related Party Lease \| Consumers Energy Company
Weighted-average discount rate
Related party lease liability	$ 1

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Carrying amount as of the balance sheet date of obligations due all related parties. For classified balance sheets, represents the current portion of such liabilities (due within one year or within the normal operating cycle if longer).

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