New Accounting Standards	3 Months Ended
New Accounting Standards	Mar. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Standards	New Accounting Standards Implementation of New Accounting Standards ASU 2016‑02, Leases: This standard, which was effective on January 1, 2019 for CMS Energy and Consumers, establishes a new accounting model for leases. The standard requires lessees to recognize lease assets and liabilities on the balance sheet for all leases with a term of more than one year, including operating leases, which were not recorded on the balance sheet under previous standards. The new guidance also amends the definition of a lease to require that a lessee have the right to control the use of a specified asset, and not simply control or take the output of the asset. On the statement of income, operating leases are generally accounted for under a straight-line expense model, while finance leases, which were previously referred to as capital leases, are generally accounted for under a financing model. Consistent with the previous lease guidance, however, the standard allows rate-regulated utilities to recognize expense consistent with the timing of recovery in rates. CMS Energy and Consumers elected to use certain practical expedients permitted by the standard, under which they were not required to perform lease assessments or reassessments for agreements existing on the effective date. They also elected a transition method under which they initially applied the standard on January 1, 2019, without adjusting amounts presented for prior periods. Under the standard, CMS Energy and Consumers recognized additional lease assets and liabilities on their consolidated balance sheets as of January 1, 2019 for their operating leases. In addition, in accordance with the standard, they have provided additional disclosures about their leases in Note 8, Leases. The standard did not have any impact on CMS Energy’s and Consumers’ consolidated net income or cash flows, and there was no cumulative-effect adjustment recorded to beginning retained earnings. New Accounting Standards Not Yet Effective ASU 2016‑13, Measurement of Credit Losses on Financial Instruments: This standard, which will be effective January 1, 2020 for CMS Energy and Consumers, provides new guidance for estimating and recording credit losses on financial instruments. The standard will apply to the recognition of loan losses at EnerBank as well as to the recognition of uncollectible accounts expense at Consumers. Entities will apply the standard using a modified retrospective approach, with a cumulative‑effect adjustment recorded to beginning retained earnings on the effective date. CMS Energy and Consumers are evaluating the impact of the standard on their consolidated financial statements.
Consumers Energy Company
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Standards	New Accounting Standards Implementation of New Accounting Standards ASU 2016‑02, Leases: This standard, which was effective on January 1, 2019 for CMS Energy and Consumers, establishes a new accounting model for leases. The standard requires lessees to recognize lease assets and liabilities on the balance sheet for all leases with a term of more than one year, including operating leases, which were not recorded on the balance sheet under previous standards. The new guidance also amends the definition of a lease to require that a lessee have the right to control the use of a specified asset, and not simply control or take the output of the asset. On the statement of income, operating leases are generally accounted for under a straight-line expense model, while finance leases, which were previously referred to as capital leases, are generally accounted for under a financing model. Consistent with the previous lease guidance, however, the standard allows rate-regulated utilities to recognize expense consistent with the timing of recovery in rates. CMS Energy and Consumers elected to use certain practical expedients permitted by the standard, under which they were not required to perform lease assessments or reassessments for agreements existing on the effective date. They also elected a transition method under which they initially applied the standard on January 1, 2019, without adjusting amounts presented for prior periods. Under the standard, CMS Energy and Consumers recognized additional lease assets and liabilities on their consolidated balance sheets as of January 1, 2019 for their operating leases. In addition, in accordance with the standard, they have provided additional disclosures about their leases in Note 8, Leases. The standard did not have any impact on CMS Energy’s and Consumers’ consolidated net income or cash flows, and there was no cumulative-effect adjustment recorded to beginning retained earnings. New Accounting Standards Not Yet Effective ASU 2016‑13, Measurement of Credit Losses on Financial Instruments: This standard, which will be effective January 1, 2020 for CMS Energy and Consumers, provides new guidance for estimating and recording credit losses on financial instruments. The standard will apply to the recognition of loan losses at EnerBank as well as to the recognition of uncollectible accounts expense at Consumers. Entities will apply the standard using a modified retrospective approach, with a cumulative‑effect adjustment recorded to beginning retained earnings on the effective date. CMS Energy and Consumers are evaluating the impact of the standard on their consolidated financial statements.