New Accounting Standards	3 Months Ended
New Accounting Standards	Mar. 31, 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. As issued, the standard will become effective January 1, 2017 for CMS Energy and Consumers; however, the Financial Accounting Standards Board has decided to propose a one-year delay in the effective date. 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 certain types of stock awards with performance targets. The standard will apply to certain restricted stock awards granted by CMS Energy and Consumers to retirement-eligible employees. CMS Energy and Consumers do not expect the standard to have any impact on their consolidated financial statements since the guidance in the standard is consistent with the accounting presently applied to these awards. 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 be 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 March 31, 2015, CMS Energy had $44 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. As issued, the standard will become effective January 1, 2017 for CMS Energy and Consumers; however, the Financial Accounting Standards Board has decided to propose a one-year delay in the effective date. 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 certain types of stock awards with performance targets. The standard will apply to certain restricted stock awards granted by CMS Energy and Consumers to retirement-eligible employees. CMS Energy and Consumers do not expect the standard to have any impact on their consolidated financial statements since the guidance in the standard is consistent with the accounting presently applied to these awards. 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 be 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 March 31, 2015, CMS Energy had $44 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.