New Accounting Standards	12 Months Ended
New Accounting Standards	Dec. 31, 2015
New Accounting Standards	2:New Accounting Standards Implementation of New Accounting Standards ASU 2015‑13, Application of the Normal Purchases and Normal Sales Scope Exception to Certain Electricity Contracts within Nodal Energy Markets: This standard, which became effective in August 2015 for CMS Energy and Consumers, was intended to resolve diversity in practice regarding whether certain electricity contracts are eligible for the normal purchases and sales scope exception from derivative accounting. The standard clarifies that contracts that require transmission of electricity through a market with established price points at each node or hub location are eligible for the scope exception. Consumers applies the normal purchases and sales scope exception to many PPAs that require transmission of electricity through the MISO market, which has price points at various node or hub locations. Since this standard clarifies that these contracts are eligible for the scope exception, which is consistent with Consumers’ treatment, the standard had no impact on CMS Energy’s or Consumers’ consolidated financial statements. ASU 2015‑17, Balance Sheet Classification of Deferred Taxes: This standard eliminates the requirement to separate deferred income tax assets and liabilities into current and non‑current amounts on a classified balance sheet. Under the standard, all deferred income tax amounts should be classified as non‑current. The standard will be effective on January 1, 2017 for CMS Energy and Consumers, but early adoption is permitted. The standard can be applied either prospectively or retrospectively. CMS Energy and Consumers elected to adopt the standard early for the year ended December 31, 2015 and applied the standard retrospectively to all prior periods. Accordingly, CMS Energy reclassified $66 million of current deferred income tax liabilities to non‑current deferred income tax liabilities at December 31, 2014, and Consumers reclassified $80 million of current deferred income tax liabilities to non‑current deferred income tax liabilities at December 31, 2014. New Accounting Standards Not Yet Effective ASU 2014‑09, Revenue from Contracts with Customers: This standard, which will become effective January 1, 2018 for CMS Energy and Consumers, provides new guidance for recognizing revenue from contracts with customers. A primary objective of the standard is to provide a single, comprehensive revenue recognition model that will be applied across entities, industries, and capital markets. 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. 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, 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, 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 have assessed this standard and do not expect that it will result in any changes to their consolidation conclusions or have any impact on their consolidated income, cash flows, or financial position. ASU 2015‑03, Simplifying the Presentation of Debt Issuance Costs: This standard, 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 December 31, 2015, CMS Energy had $41 million of unamortized debt issuance costs, which included $23 million at Consumers. These amounts were recorded in other non‑current assets on the consolidated balance sheets, but will be included in the long-term debt balances under this standard. ASU 2016‑01, Recognition and Measurement of Financial Assets and Financial Liabilities: This standard, which will be effective January 1, 2018 for CMS Energy and Consumers, is intended to improve the accounting for financial instruments. The standard will require investments in equity securities to be measured at fair value, with changes in fair value recognized in net income, except for certain investments such as those that qualify for equity-method accounting. The standard will no longer permit unrealized gains and losses for certain equity investments to be recorded in AOCI. CMS Energy and Consumers presently record unrealized gains and losses on certain equity investments, including the mutual funds in the DB SERP and Consumers’ investment in CMS Energy common stock, in AOCI. During the year ended December 31, 2015, CMS Energy recorded a $3 million unrealized net loss on equity investments in AOCI and Consumers recorded a $1 million unrealized net loss on equity investments in AOCI. For further details on these investments, see Note 7, Financial Instruments. 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 whether there may be further impacts of the standard on their consolidated financial statements.
Consumers Energy Company [Member]
New Accounting Standards	2:New Accounting Standards Implementation of New Accounting Standards ASU 2015‑13, Application of the Normal Purchases and Normal Sales Scope Exception to Certain Electricity Contracts within Nodal Energy Markets: This standard, which became effective in August 2015 for CMS Energy and Consumers, was intended to resolve diversity in practice regarding whether certain electricity contracts are eligible for the normal purchases and sales scope exception from derivative accounting. The standard clarifies that contracts that require transmission of electricity through a market with established price points at each node or hub location are eligible for the scope exception. Consumers applies the normal purchases and sales scope exception to many PPAs that require transmission of electricity through the MISO market, which has price points at various node or hub locations. Since this standard clarifies that these contracts are eligible for the scope exception, which is consistent with Consumers’ treatment, the standard had no impact on CMS Energy’s or Consumers’ consolidated financial statements. ASU 2015‑17, Balance Sheet Classification of Deferred Taxes: This standard eliminates the requirement to separate deferred income tax assets and liabilities into current and non‑current amounts on a classified balance sheet. Under the standard, all deferred income tax amounts should be classified as non‑current. The standard will be effective on January 1, 2017 for CMS Energy and Consumers, but early adoption is permitted. The standard can be applied either prospectively or retrospectively. CMS Energy and Consumers elected to adopt the standard early for the year ended December 31, 2015 and applied the standard retrospectively to all prior periods. Accordingly, CMS Energy reclassified $66 million of current deferred income tax liabilities to non‑current deferred income tax liabilities at December 31, 2014, and Consumers reclassified $80 million of current deferred income tax liabilities to non‑current deferred income tax liabilities at December 31, 2014. New Accounting Standards Not Yet Effective ASU 2014‑09, Revenue from Contracts with Customers: This standard, which will become effective January 1, 2018 for CMS Energy and Consumers, provides new guidance for recognizing revenue from contracts with customers. A primary objective of the standard is to provide a single, comprehensive revenue recognition model that will be applied across entities, industries, and capital markets. 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. 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, 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, 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 have assessed this standard and do not expect that it will result in any changes to their consolidation conclusions or have any impact on their consolidated income, cash flows, or financial position. ASU 2015‑03, Simplifying the Presentation of Debt Issuance Costs: This standard, 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 December 31, 2015, CMS Energy had $41 million of unamortized debt issuance costs, which included $23 million at Consumers. These amounts were recorded in other non‑current assets on the consolidated balance sheets, but will be included in the long-term debt balances under this standard. ASU 2016‑01, Recognition and Measurement of Financial Assets and Financial Liabilities: This standard, which will be effective January 1, 2018 for CMS Energy and Consumers, is intended to improve the accounting for financial instruments. The standard will require investments in equity securities to be measured at fair value, with changes in fair value recognized in net income, except for certain investments such as those that qualify for equity-method accounting. The standard will no longer permit unrealized gains and losses for certain equity investments to be recorded in AOCI. CMS Energy and Consumers presently record unrealized gains and losses on certain equity investments, including the mutual funds in the DB SERP and Consumers’ investment in CMS Energy common stock, in AOCI. During the year ended December 31, 2015, CMS Energy recorded a $3 million unrealized net loss on equity investments in AOCI and Consumers recorded a $1 million unrealized net loss on equity investments in AOCI. For further details on these investments, see Note 7, Financial Instruments. 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 whether there may be further impacts of the standard on their consolidated financial statements.