New Accounting Standards	6 Months Ended
New Accounting Standards	Jun. 30, 2015
New Accounting Standards	1:New Accounting Standards New Accounting Standards Not Yet Effective ASU 2014‑09, Revenue from Contracts with Customers: This standard was issued by the Financial Accounting Standards Board as a result of a joint project with the International Accounting Standards Board. The Boards developed a common revenue recognition model that will be applied under GAAP and International Financial Reporting Standards. The new guidance will replace most of the existing revenue recognition requirements in GAAP, although certain guidance specific to rate-regulated utilities will be retained. The standard is expected to become effective January 1, 2018 for CMS Energy and Consumers. Entities will have the option to apply the standard retrospectively to all prior periods presented, or to apply it retrospectively only to contracts existing at the effective date, with the cumulative effect of the standard recorded as an adjustment to beginning retained earnings. CMS Energy and Consumers are evaluating the impact of the standard on their consolidated financial statements. ASU 2014‑12, Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period: This standard, which will become effective January 1, 2016 for CMS Energy and Consumers, addresses stock awards with performance targets that can be met after an employee has completed the required service period. The standard was intended to resolve diversity in practice regarding the accounting treatment for this type of award. Under the new guidance, the probability of the performance target being met should be factored into compensation expense each period. This guidance is consistent with the accounting that CMS Energy and Consumers already apply to awards of this type. Therefore, CMS Energy and Consumers do not expect the standard to impact their consolidated financial statements. ASU 2015‑02, Amendments to the Consolidation Analysis: This standard, which will become effective January 1, 2016 for CMS Energy and Consumers, provides amended guidance on whether reporting entities should consolidate certain legal entities, including limited partnerships. CMS Energy and Consumers are evaluating the impact of the standard on their consolidated financial statements. ASU 2015‑03, Simplifying the Presentation of Debt Issuance Costs: This standard, which will become effective January 1, 2016 for CMS Energy and Consumers, requires that debt issuance costs be presented as a direct deduction from the carrying amount of long-term debt on the balance sheet. Presently, debt issuance costs are reported as an asset. The new guidance aligns the presentation of debt issuance costs with debt discounts and premiums. The standard is to be applied retrospectively to all prior periods presented. At June 30, 2015, CMS Energy had $43 million of unamortized debt issuance costs, which included $23 million at Consumers. These amounts are recorded in other non‑current assets on the consolidated balance sheets.
Consumers Energy Company [Member]
New Accounting Standards	1:New Accounting Standards New Accounting Standards Not Yet Effective ASU 2014‑09, Revenue from Contracts with Customers: This standard was issued by the Financial Accounting Standards Board as a result of a joint project with the International Accounting Standards Board. The Boards developed a common revenue recognition model that will be applied under GAAP and International Financial Reporting Standards. The new guidance will replace most of the existing revenue recognition requirements in GAAP, although certain guidance specific to rate-regulated utilities will be retained. The standard is expected to become effective January 1, 2018 for CMS Energy and Consumers. Entities will have the option to apply the standard retrospectively to all prior periods presented, or to apply it retrospectively only to contracts existing at the effective date, with the cumulative effect of the standard recorded as an adjustment to beginning retained earnings. CMS Energy and Consumers are evaluating the impact of the standard on their consolidated financial statements. ASU 2014‑12, Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period: This standard, which will become effective January 1, 2016 for CMS Energy and Consumers, addresses stock awards with performance targets that can be met after an employee has completed the required service period. The standard was intended to resolve diversity in practice regarding the accounting treatment for this type of award. Under the new guidance, the probability of the performance target being met should be factored into compensation expense each period. This guidance is consistent with the accounting that CMS Energy and Consumers already apply to awards of this type. Therefore, CMS Energy and Consumers do not expect the standard to impact their consolidated financial statements. ASU 2015‑02, Amendments to the Consolidation Analysis: This standard, which will become effective January 1, 2016 for CMS Energy and Consumers, provides amended guidance on whether reporting entities should consolidate certain legal entities, including limited partnerships. CMS Energy and Consumers are evaluating the impact of the standard on their consolidated financial statements. ASU 2015‑03, Simplifying the Presentation of Debt Issuance Costs: This standard, which will become effective January 1, 2016 for CMS Energy and Consumers, requires that debt issuance costs be presented as a direct deduction from the carrying amount of long-term debt on the balance sheet. Presently, debt issuance costs are reported as an asset. The new guidance aligns the presentation of debt issuance costs with debt discounts and premiums. The standard is to be applied retrospectively to all prior periods presented. At June 30, 2015, CMS Energy had $43 million of unamortized debt issuance costs, which included $23 million at Consumers. These amounts are recorded in other non‑current assets on the consolidated balance sheets.