Significant Accounting Policies (Policy)	12 Months Ended
Dec. 31, 2011
Corporate Structure	Corporate Structure: CMS Energy is an energy company operating primarily in Michigan. It is the parent holding company of several subsidiaries, including Consumers, an electric and gas utility, and CMS Enterprises, primarily a domestic independent power producer. CMS Energy and Consumers manage their businesses by the nature of services each provides. CMS Energy operates principally in three business segments: electric utility; gas utility; and enterprises, its non-utility investments and operations. Consumers operates principally in two business segments: electric utility and gas utility.
Principles of Consolidation	Principles of Consolidation: CMS Energy and Consumers prepare their consolidated financial statements in conformity with GAAP. CMS Energy's consolidated financial statements comprise CMS Energy, Consumers, CMS Enterprises, and all other entities in which CMS Energy has a controlling financial interest or is the primary beneficiary. Consumers' consolidated financial statements comprise Consumers and all other entities in which it has a controlling financial interest or is the primary beneficiary. CMS Energy uses the equity method of accounting for investments in companies and partnerships that are not consolidated, where they have significant influence over operations and financial policies but are not the primary beneficiary. CMS Energy and Consumers eliminate intercompany transactions and balances.
Use of Estimates	Use of Estimates: CMS Energy and Consumers are required to make estimates using assumptions that may affect reported amounts and disclosures. Actual results could differ from those estimates.
Revenue Recognition Policy - General	Revenue Recognition Policy: CMS Energy and Consumers recognize revenue from deliveries of electricity and natural gas, and from the transportation, processing, and storage of natural gas, when services are provided. CMS Energy and Consumers record unbilled revenue for the estimated amount of energy delivered to customers but not yet billed. CMS Energy and Consumers record sales tax net and exclude it from revenue. CMS Energy recognizes revenue on sales of marketed electricity, natural gas, and other energy products at delivery.
Revenue Recognition Policy - Alternative-Revenue Programs	Alternative-Revenue Programs: Under electric and gas rate cse orders issued by the MPSC in 2009 and 2010, Consumers was granted authority to implement revenue decoupling mechanisms. The electric revenue decoupling mechanism adjusts customer rates to collect or refund the change in marginal revenue arising from the difference between the level of average sales per customer adopted in the electric rate case order and actual average sales per customer. The gas revenue decoupling mechanism is similar, but does not adjust customer rates for changes in sales volumes resulting from weather fluctuations. Consumers accounts for these programs as alternative-revenue programs that meet the criteria for recognizing the effects of decoupling adjustments on revenue as electricity and gas are delivered. For details on Consumers' decoupling mechanisms, see Note 6, Regulatory Matters. In September 2009, the MPSC approved an energy optimization incentive mechanism that provides a financial incentive if the energy savings of Consumers' customers exceed annual targets established by the MPSC. Consumers accounts for this program as an alternative-revenue program that meets the criteria for recognizing revenue related to the incentive as soon as energy savings exceed the annual targets established by the MPSC.
Revenue Recognition Policy - Self-Implemented Rates	Self-Implemented Rates: Unless prohibited by the MPSC upon a showing of good cause, Consumers is allowed to self-implement new energy rates six months after a new rate case filing if the MPSC has not issued an order in the case. The MPSC then has another six months to issue a final order. If the MPSC does not issue a final order within the period, the filed rates are considered approved. If the MPSC issues a final order within the period, the rates that Consumers self-implemented may be subject to refund, with interest. Consumers recognizes revenue associated with self-implemented rates. If Consumers considers it probable that it will be required to refund a portion of its self-implemented rates, then Consumers records a provision for revenue subject to refund. For details on Consumers' self-implemented rates, see Note 6, Regulatory Matters.
Accounts Receivable	Accounts Receivable: Accounts receivable comprise trade receivables and unbilled receivables. CMS Energy and Consumers record their accounts receivable at cost, which approximates fair value. CMS Energy and Consumers establish an allowance for uncollectible accounts based on historical losses, management's assessment of existing economic conditions, customer trends, and other factors. CMS Energy and Consumers assess late payment fees on trade receivables based on contractual past-due terms established with customers. CMS Energy and Consumers charge off accounts deemed uncollectible to operating expense.
Allowance for Uncollectible Notes Receivable	Allowance for Uncollectible Notes Receivable: The allowance for uncollectible notes receivable is a valuation allowance to reflect possible credit losses. The allowance is increased by the provision for credit losses and decreased by note charge-offs net of recoveries. Management estimates the allowance balance required using historical loan loss experience, the nature and volume of the portfolio, economic conditions, and other factors. Notes deemed uncollectible are charged against the allowance when the loss is confirmed, but no later than the point at which a note becomes 120 days past due. For further details about CMS Energy's notes receivable, see Note 9, Financial Instruments and Note 11, Notes Receivable.
Cash and Cash Equivalents	Cash and Cash Equivalents: Cash and cash equivalents include short-term, highly liquid investments with original maturities of three months or less.
Contingencies	Contingencies: CMS Energy and Consumers record estimated liabilities for contingencies in their consolidated financial statements when it is probable that a liability has been incurred and when the amount of loss can be reasonably estimated. CMS Energy and Consumers expense legal fees as incurred; fees incurred but not yet billed are accrued based on estimates of work performed. This policy also applies to any fees incurred on behalf of employees and officers under indemnification agreements; such fees are billed directly to CMS Energy or Consumers.
Debt Issuance Costs, Discounts, Premiums, and Refinancing Costs	Debt Issuance Costs, Discounts, Premiums, and Refinancing Costs: CMS Energy and Consumers defer issuance costs, discounts, and premiums associated with long-term debt and amortize those amounts over the terms of the debt issues. For the non-regulated portions of CMS Energy's and Consumers' businesses, refinancing costs are expensed as incurred. For the regulated portions of CMS Energy's and Consumers' businesses, any remaining unamortized issuance costs, discounts, and premiums associated with refinanced debt are amortized over the term of the newly issued debt.
Derivative Instruments	Derivative Instruments: CMS Energy and Consumers record derivative contracts that do not qualify for the normal purchases and sales exception at fair value on their consolidated balance sheets. Each reporting period, the resulting asset or liability is adjusted to reflect any change in the fair value of the contract. Since none of CMS Energy's or Consumers' derivatives has been designated as an accounting hedge, all changes in fair value are reported in earnings. For a discussion of how CMS Energy and Consumers determine the fair value of their derivatives, see Note 4, Fair Value Measurements. For additional details regarding derivative instruments, see Note 10, Derivative Instruments.
Determination of Pension and OPEB MRV of Plan Assets	Determination of Pension and OPEB MRV of Plan Assets: CMS Energy and Consumers determine the MRV for pension plan assets as the fair value of plan assets on the measurement date, adjusted by the gains or losses that will not be admitted into the MRV until future years. CMS Energy and Consumers reflect each year's gain or loss in the MRV in equal amounts over a five-year period beginning on the date the original amount was determined. CMS Energy and Consumers determine the MRV for OPEB plan assets as the fair value of assets on the measurement date. CMS Energy and Consumers use the MRV in the calculation of net pension and OPEB costs. For further details, see Note 12, Retirement Benefits.
Earnings Per Share	Earnings Per Share: CMS Energy calculates basic and diluted EPS using the weighted-average number of shares of common stock and dilutive potential common stock outstanding during the period. Potential common stock, for purposes of determining diluted EPS, includes the effects of dilutive stock options, warrants, and convertible securities. CMS Energy computes the effect on potential common stock using the treasury stock method or the if-converted method, as applicable. Diluted EPS excludes the impact of antidilutive securities, which are those securities resulting in an increase in EPS or a decrease in loss per share. For EPS computations, see Note 8, Earnings Per Share – CMS Energy.
Financial Instruments	Financial Instruments: CMS Energy and Consumers record debt and equity securities classified as available for sale at fair value as determined from quoted market prices or other observable, market-based inputs. Unrealized gains and losses on these securities are determined on a specific-identification basis. CMS Energy and Consumers report unrealized gains and losses from changes in fair value of the equity securities, net of tax, in equity as part of AOCI, except that unrealized losses determined to be other than temporary are reported in earnings. CMS Energy and Consumers report unrealized gains resulting from changes in fair value of the debt securities, net of tax, in equity as part of AOCI. Unrealized losses on the debt securities, if significant, are considered other than temporary and reported in earnings since these securities are managed by an independent investment manager that can sell the securities at its own discretion. For additional details regarding financial instruments, see Note 9, Financial Instruments.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets and Equity Method Investments: CMS Energy and Consumers perform tests of impairment if certain triggering events occur, or if there has been a decline in value that may be other than temporary. CMS Energy and Consumers evaluate long-lived assets held in use for impairment by calculating the undiscounted future cash flows expected to result from the use of the asset and its eventual disposition. If the undiscounted future cash flows are less than the carrying amount, CMS Energy and Consumers recognize an impairment loss equal to the amount by which the carrying amount exceeds the fair value. CMS Energy and Consumers estimate the fair value of the asset using quoted market prices, market prices of similar assets, or discounted future cash flow analyses.
Impairment of Equity Method Investments	CMS Energy also assesses equity method investments for impairment whenever there has been a decline in value that is other than temporary. This assessment requires CMS Energy to determine the fair value of the equity method investment. CMS Energy determines fair value using valuation methodologies, including discounted cash flows, and assesses the ability of the investee to sustain an earnings capacity that justifies the carrying amount of the investment. CMS Energy records an impairment if the fair value is less than the carrying amount and the decline in value is considered to be other than temporary. For additional details, see Note 20, Asset Sales, Discontinued Operations, and Impairment Charges.
Inventory - Gas and Coal	Inventory: CMS Energy and Consumers use the weighted-average cost method for valuing working gas, recoverable base gas in underground storage facilities, and materials and supplies inventory. CMS Energy and Consumers also use this method for valuing coal inventory, and they classify these amounts as generating plant fuel stock on their consolidated balance sheets.
Inventory - RECs and Emission Allowances	CMS Energy and Consumers classify RECs and emission allowances as materials and supplies inventory and use the weighted average method to remove amounts from inventory. RECs and emission allowances are used to satisfy compliance obligations related to the generation of power.
Inventory - Impairment	CMS Energy and Consumers use the lower-of-cost-or-market method to evaluate inventory for impairment.
Accounting for MISO Transactions	MISO Transactions: MISO requires the submission of hourly day-ahead and real-time bids and offers for energy at locations across the MISO region. Consumers and CMS ERM account for MISO transactions on a net hourly basis in each of the real-time and day-ahead markets, and they net transactions across all MISO energy market locations. CMS Energy and Consumers record net purchases in a single hour in purchased and interchange power and net sales in a single hour in operating revenue on the consolidated statements of income. They record net sale billing adjustments upon invoice receipt, record expense accruals for future net purchases adjustments based on historical experience, and reconcile accruals to actual expenses upon invoice receipt.
Property Taxes	Property Taxes: Property taxes are based on the taxable value of Consumers' real and personal property assessed by local taxing authorities. Consumers records property tax expense over the fiscal year of the taxing authority for which the taxes are levied based on Consumers' budgeted customer sales. The deferred property tax balance represents the amount of Consumers' accrued property tax that will be recognized over future governmental fiscal periods.
Restricted Cash and Cash Equivalents	Restricted Cash and Cash Equivalents: CMS Energy and Consumers have restricted cash and cash equivalents dedicated for repayment of Securitization bonds and for payment under performance guarantees. CMS Energy and Consumers classify these amounts as a current asset if they relate to payments that could or will occur within one year.
Consumers Energy Company [Member]
Corporate Structure	Corporate Structure: CMS Energy is an energy company operating primarily in Michigan. It is the parent holding company of several subsidiaries, including Consumers, an electric and gas utility, and CMS Enterprises, primarily a domestic independent power producer. CMS Energy and Consumers manage their businesses by the nature of services each provides. CMS Energy operates principally in three business segments: electric utility; gas utility; and enterprises, its non-utility investments and operations. Consumers operates principally in two business segments: electric utility and gas utility.
Principles of Consolidation	Principles of Consolidation: CMS Energy and Consumers prepare their consolidated financial statements in conformity with GAAP. CMS Energy's consolidated financial statements comprise CMS Energy, Consumers, CMS Enterprises, and all other entities in which CMS Energy has a controlling financial interest or is the primary beneficiary. Consumers' consolidated financial statements comprise Consumers and all other entities in which it has a controlling financial interest or is the primary beneficiary. CMS Energy uses the equity method of accounting for investments in companies and partnerships that are not consolidated, where they have significant influence over operations and financial policies but are not the primary beneficiary. CMS Energy and Consumers eliminate intercompany transactions and balances.
Use of Estimates	Use of Estimates: CMS Energy and Consumers are required to make estimates using assumptions that may affect reported amounts and disclosures. Actual results could differ from those estimates.
Revenue Recognition Policy - General	Revenue Recognition Policy: CMS Energy and Consumers recognize revenue from deliveries of electricity and natural gas, and from the transportation, processing, and storage of natural gas, when services are provided. CMS Energy and Consumers record unbilled revenue for the estimated amount of energy delivered to customers but not yet billed. CMS Energy and Consumers record sales tax net and exclude it from revenue. CMS Energy recognizes revenue on sales of marketed electricity, natural gas, and other energy products at delivery.
Revenue Recognition Policy - Alternative-Revenue Programs	Alternative-Revenue Programs: Under electric and gas rate cases orders issued by the MPSC in 2009 and 2010, Consumers was granted authority to implement revenue decoupling mechanisms. The electric revenue decoupling mechanism adjusts customer rates to collect or refund the change in marginal revenue arising from the difference between the level of average sales per customer adopted in the electric rate case order and actual average sales per customer. The gas revenue decoupling mechanism is similar, but does not adjust customer rates for changes in sales volumes resulting from weather fluctuations. Consumers accounts for these programs as alternative-revenue programs that meet the criteria for recognizing the effects of decoupling adjustments on revenue as electricity and gas are delivered. For details on Consumers' decoupling mechanisms, see Note 6, Regulatory Matters. In September 2009, the MPSC approved an energy optimization incentive mechanism that provides a financial incentive if the energy savings of the Consumers' customers exceed annual targets established by the MPSC. Consumers accounts for this program as an alternative-revenue program that meets the criteria for recognizing revenue related to the incentive as soon as energy savings exceed the annual targets established by the MPSC.
Revenue Recognition Policy - Self-Implemented Rates	Self-Implemented Rates: Unless prohibited by the MPSC upon a showing of good cause, Consumers is allowed to self-implement new energy rates six months after a new rate case filing if the MPSC has not issued an order in the case. The MPSC then has another six months to issue a final order. If the MPSC does not issue a final order within that period, the filed rates are considered approved. If the MPSC issues a final order within that period, the rates that Consumers self-implemented may be subject to refund, with interest. Consumers recognizes revenue associated with self-implemented rates. If Consumers considers it probable that it will be required to refund a portion of its self-implemented rates, then Consumers records a provision for revenue subject to refund. For details on Consumers' self-implemented rates, see Note 6, Regulatory Matters.
Accounts Receivable	Accounts Receivable: Accounts receivable comprise trade receivables and unbilled receivables. CMS Energy and Consumers record their accounts receivable at cost, which approximates fair value. CMS Energy and Consumers establish an allowance for uncollectible accounts based on historical losses, management's assessment of existing economic conditions, customer trends, and other factors. CMS Energy and Consumers assess late payment fees on trade receivables based on contractual past-due terms established with customers. CMS Energy and Consumers charge off accounts deemed uncollectible to operating expense.
Cash and Cash Equivalents	Cash and Cash Equivalents: Cash and cash equivalents include short-term, highly liquid investments with original maturities of three months or less.
Contingencies	Contingencies: CMS Energy and Consumers record estimated liabilities for contingencies on their consolidated financial statements when it is probable that a liability has been incurred and when the amount of loss can be reasonably estimated. CMS Energy and Consumers expense legal fees as incurred; fees incurred but not yet billed are accrued based on estimates of work performed. This policy also applies to any fees incurred on behalf of employees and officers under indemnification agreements; such fees are billed directly to CMS Energy or Consumers.
Debt Issuance Costs, Discounts, Premiums, and Refinancing Costs	Debt Issuance Costs, Discounts, Premiums, and Refinancing Costs: CMS Energy and Consumers defer issuance costs, discounts, and premiums associated with long-term debt and amortize those amounts over the terms of the debt issues. For the non-regulated portions of CMS Energy's and Consumers' businesses, refinancing costs are expensed as incurred. For the regulated portions of CMS Energy's and Consumers' businesses, any remaining unamortized issuance costs, discounts, and premiums associated with refinanced debt are amortized over the term of the newly issued debt.
Derivative Instruments	Derivative Instruments: CMS Energy and Consumers record derivative contracts that do not qualify for the normal purchases and sales exception at fair value on their consolidated balance sheets. Each reporting period, the resulting asset or liability is adjusted to reflect any change in the fair value of the contract. Since none of CMS Energy's or Consumers' derivatives has been designated as an accounting hedge, all changes in fair value are reported in earnings. For a discussion of how CMS Energy and Consumers determine the fair value of their derivatives, see Note 4, Fair Value Measurements. For additional details regarding derivative instruments, see Note 10, Derivative Instruments.
Determination of Pension and OPEB MRV of Plan Assets	Determination of Pension and OPEB MRV of Plan Assets: CMS Energy and Consumers determine the MRV for pension plan assets as the fair value of plan assets on the measurement date, adjusted by the gains or losses that will not be admitted into the MRV until future years. CMS Energy and Consumers reflect each year's gain or loss in the MRV in equal amounts over a five-year period beginning on the date the original amount was determined. CMS Energy and Consumers determine the MRV for OPEB plan assets as the fair value of assets on the measurement date. CMS Energy and Consumers use the MRV in the calculation of net pension and OPEB costs. For further details, see Note 12, Retirement Benefits.
Financial Instruments	Financial Instruments: CMS Energy and Consumers record debt and equity securities classified as available for sale at fair value as determined from quoted market prices or other observable, market-based inputs. Unrealized gains and losses on these securities are determined on a specific-identification basis. CMS Energy and Consumers report unrealized gains and losses from changes in fair value of the equity securities, net of tax, in equity as part of AOCI, except that unrealized losses determined to be other than temporary are reported in earnings. CMS Energy and Consumers report unrealized gains resulting from changes in fair value of the debt securities, net of tax, in equity as part of AOCI. Unrealized losses on the debt securities, if significant, are considered other than temporary and reported in earnings since these securities are managed by an independent investment manager that can sell the securities at its own discretion. For additional details regarding financial instruments, see Note 9, Financial Instruments.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets and Equity Method Investments: CMS Energy and Consumers perform tests of impairment if certain triggering events occur, or if there has been a decline in value that may be other than temporary. CMS Energy and Consumers evaluate long-lived assets held in use for impairment by calculating the undiscounted future cash flows expected to result from the use of the asset and its eventual disposition. If the undiscounted future cash flows are less than the carrying amount, CMS Energy and Consumers recognize an impairment loss equal to the amount by which the carrying amount exceeds the fair value. CMS Energy and Consumers estimate the fair value of the asset using quoted market prices, market prices of similar assets, or discounted future cash flow analyses.
Inventory - Gas and Coal	Inventory: CMS Energy and Consumers use the weighted-average cost method for valuing working gas, recoverable base gas in underground storage facilities, and materials and supplies inventory. CMS Energy and Consumers also use this method for valuing coal inventory, and they classify these amounts as generating plant fuel stock on their consolidated balance sheets.
Inventory - RECs and Emission Allowances	CMS Energy and Consumers classify RECs and emission allowances as materials and supplies inventory and use the weighted average method to remove amounts from inventory. RECs and emission allowances are used to satisfy compliance obligations related to the generation of power.
Inventory - Impairment	CMS Energy and Consumers use the lower-of-cost-or-market method to evaluate inventory for impairment.
Accounting for MISO Transactions	MISO Transactions: MISO requires the submission of hourly day-ahead and real-time bids and offers for energy at locations across the MISO region. Consumers and CMS ERM account for MISO transactions on a net hourly basis in each of the real-time and day-ahead markets, and they net transactions across all MISO energy market locations. CMS Energy and Consumers record net purchases in a single hour in purchased and interchange power and net sales in a single hour in operating revenue on the consolidated statements of income. They record net sale billing adjustments upon invoice receipt, record expense accruals for future net purchases adjustments based on historical experience, and reconcile accruals to actual expenses upon invoice receipt.
Property Taxes	Property Taxes: Property taxes are based on the taxable value of Consumers' real and personal property assessed by local taxing authorities. Consumers records property tax expense over the fiscal year of the taxing authority for which the taxes are levied based on Consumers' budgeted customer sales. The deferred property tax balance represents the amount of Consumers' accrued property tax that will be recognized over future governmental fiscal periods.
Restricted Cash and Cash Equivalents	Restricted Cash and Cash Equivalents: CMS Energy and Consumers have restricted cash and cash equivalents dedicated for repayment of Securitization bonds and for payment under performance guarantees. CMS Energy and Consumers classify these amounts as a current asset if they relate to payments that could or will occur within one year.

Significant Accounting Policies (Policy)

12 Months Ended

Dec. 31, 2011

Corporate Structure: CMS Energy is an energy company operating primarily in Michigan. It is the parent holding company of several subsidiaries, including Consumers, an electric and gas utility, and CMS Enterprises, primarily a domestic independent power producer. CMS Energy and Consumers manage their businesses by the nature of services each provides. CMS Energy operates principally in three business segments: electric utility; gas utility; and enterprises, its non-utility investments and operations. Consumers operates principally in two business segments: electric utility and gas utility.

Principles of Consolidation

Principles of Consolidation: CMS Energy and Consumers prepare their consolidated financial statements in conformity with GAAP. CMS Energy's consolidated financial statements comprise CMS Energy, Consumers, CMS Enterprises, and all other entities in which CMS Energy has a controlling financial interest or is the primary beneficiary. Consumers' consolidated financial statements comprise Consumers and all other entities in which it has a controlling financial interest or is the primary beneficiary. CMS Energy uses the equity method of accounting for investments in companies and partnerships that are not consolidated, where they have significant influence over operations and financial policies but are not the primary beneficiary. CMS Energy and Consumers eliminate intercompany transactions and balances.

Use of Estimates

Use of Estimates: CMS Energy and Consumers are required to make estimates using assumptions that may affect reported amounts and disclosures. Actual results could differ from those estimates.

Revenue Recognition Policy - General

Revenue Recognition Policy: CMS Energy and Consumers recognize revenue from deliveries of electricity and natural gas, and from the transportation, processing, and storage of natural gas, when services are provided. CMS Energy and Consumers record unbilled revenue for the estimated amount of energy delivered to customers but not yet billed. CMS Energy and Consumers record sales tax net and exclude it from revenue. CMS Energy recognizes revenue on sales of marketed electricity, natural gas, and other energy products at delivery.

Revenue Recognition Policy - Alternative-Revenue Programs

Alternative-Revenue Programs: Under electric and gas rate cse orders issued by the MPSC in 2009 and 2010, Consumers was granted authority to implement revenue decoupling mechanisms. The electric revenue decoupling mechanism adjusts customer rates to collect or refund the change in marginal revenue arising from the difference between the level of average sales per customer adopted in the electric rate case order and actual average sales per customer. The gas revenue decoupling mechanism is similar, but does not adjust customer rates for changes in sales volumes resulting from weather fluctuations. Consumers accounts for these programs as alternative-revenue programs that meet the criteria for recognizing the effects of decoupling adjustments on revenue as electricity and gas are delivered. For details on Consumers' decoupling mechanisms, see Note 6, Regulatory Matters.

In September 2009, the MPSC approved an energy optimization incentive mechanism that provides a financial incentive if the energy savings of Consumers' customers exceed annual targets established by the MPSC. Consumers accounts for this program as an alternative-revenue program that meets the criteria for recognizing revenue related to the incentive as soon as energy savings exceed the annual targets established by the MPSC.

Revenue Recognition Policy - Self-Implemented Rates

Self-Implemented Rates: Unless prohibited by the MPSC upon a showing of good cause, Consumers is allowed to self-implement new energy rates six months after a new rate case filing if the MPSC has not issued an order in the case. The MPSC then has another six months to issue a final order. If the MPSC does not issue a final order within the period, the filed rates are considered approved. If the MPSC issues a final order within the period, the rates that Consumers self-implemented may be subject to refund, with interest. Consumers recognizes revenue associated with self-implemented rates. If Consumers considers it probable that it will be required to refund a portion of its self-implemented rates, then Consumers records a provision for revenue subject to refund. For details on Consumers' self-implemented rates, see Note 6, Regulatory Matters.

Accounts Receivable

Accounts Receivable: Accounts receivable comprise trade receivables and unbilled receivables. CMS Energy and Consumers record their accounts receivable at cost, which approximates fair value. CMS Energy and Consumers establish an allowance for uncollectible accounts based on historical losses, management's assessment of existing economic conditions, customer trends, and other factors. CMS Energy and Consumers assess late payment fees on trade receivables based on contractual past-due terms established with customers. CMS Energy and Consumers charge off accounts deemed uncollectible to operating expense.

Allowance for Uncollectible Notes Receivable

Allowance for Uncollectible Notes Receivable: The allowance for uncollectible notes receivable is a valuation allowance to reflect possible credit losses. The allowance is increased by the provision for credit losses and decreased by note charge-offs net of recoveries. Management estimates the allowance balance required using historical loan loss experience, the nature and volume of the portfolio, economic conditions, and other factors. Notes deemed uncollectible are charged against the allowance when the loss is confirmed, but no later than the point at which a note becomes 120 days past due. For further details about CMS Energy's notes receivable, see Note 9, Financial Instruments and Note 11, Notes Receivable.

Cash and Cash Equivalents

Cash and Cash Equivalents: Cash and cash equivalents include short-term, highly liquid investments with original maturities of three months or less.

Contingencies

Contingencies: CMS Energy and Consumers record estimated liabilities for contingencies in their consolidated financial statements when it is probable that a liability has been incurred and when the amount of loss can be reasonably estimated. CMS Energy and Consumers expense legal fees as incurred; fees incurred but not yet billed are accrued based on estimates of work performed. This policy also applies to any fees incurred on behalf of employees and officers under indemnification agreements; such fees are billed directly to CMS Energy or Consumers.

Debt Issuance Costs, Discounts, Premiums, and Refinancing Costs

Debt Issuance Costs, Discounts, Premiums, and Refinancing Costs: CMS Energy and Consumers defer issuance costs, discounts, and premiums associated with long-term debt and amortize those amounts over the terms of the debt issues. For the non-regulated portions of CMS Energy's and Consumers' businesses, refinancing costs are expensed as incurred. For the regulated portions of CMS Energy's and Consumers' businesses, any remaining unamortized issuance costs, discounts, and premiums associated with refinanced debt are amortized over the term of the newly issued debt.

Derivative Instruments

Derivative Instruments: CMS Energy and Consumers record derivative contracts that do not qualify for the normal purchases and sales exception at fair value on their consolidated balance sheets. Each reporting period, the resulting asset or liability is adjusted to reflect any change in the fair value of the contract. Since none of CMS Energy's or Consumers' derivatives has been designated as an accounting hedge, all changes in fair value are reported in earnings. For a discussion of how CMS Energy and Consumers determine the fair value of their derivatives, see Note 4, Fair Value Measurements. For additional details regarding derivative instruments, see Note 10, Derivative Instruments.

Determination of Pension and OPEB MRV of Plan Assets

Determination of Pension and OPEB MRV of Plan Assets: CMS Energy and Consumers determine the MRV for pension plan assets as the fair value of plan assets on the measurement date, adjusted by the gains or losses that will not be admitted into the MRV until future years. CMS Energy and Consumers reflect each year's gain or loss in the MRV in equal amounts over a five-year period beginning on the date the original amount was determined. CMS Energy and Consumers determine the MRV for OPEB plan assets as the fair value of assets on the measurement date. CMS Energy and Consumers use the MRV in the calculation of net pension and OPEB costs. For further details, see Note 12, Retirement Benefits.

Earnings Per Share

Earnings Per Share: CMS Energy calculates basic and diluted EPS using the weighted-average number of shares of common stock and dilutive potential common stock outstanding during the period. Potential common stock, for purposes of determining diluted EPS, includes the effects of dilutive stock options, warrants, and convertible securities. CMS Energy computes the effect on potential common stock using the treasury stock method or the if-converted method, as applicable. Diluted EPS excludes the impact of antidilutive securities, which are those securities resulting in an increase in EPS or a decrease in loss per share. For EPS computations, see Note 8, Earnings Per Share – CMS Energy.

Financial Instruments

Financial Instruments: CMS Energy and Consumers record debt and equity securities classified as available for sale at fair value as determined from quoted market prices or other observable, market-based inputs. Unrealized gains and losses on these securities are determined on a specific-identification basis. CMS Energy and Consumers report unrealized gains and losses from changes in fair value of the equity securities, net of tax, in equity as part of AOCI, except that unrealized losses determined to be other than temporary are reported in earnings. CMS Energy and Consumers report unrealized gains resulting from changes in fair value of the debt securities, net of tax, in equity as part of AOCI. Unrealized losses on the debt securities, if significant, are considered other than temporary and reported in earnings since these securities are managed by an independent investment manager that can sell the securities at its own discretion. For additional details regarding financial instruments, see Note 9, Financial Instruments.

Impairment of Long-Lived Assets

Impairment of Long-Lived Assets and Equity Method Investments: CMS Energy and Consumers perform tests of impairment if certain triggering events occur, or if there has been a decline in value that may be other than temporary.

CMS Energy and Consumers evaluate long-lived assets held in use for impairment by calculating the undiscounted future cash flows expected to result from the use of the asset and its eventual disposition. If the undiscounted future cash flows are less than the carrying amount, CMS Energy and Consumers recognize an impairment loss equal to the amount by which the carrying amount exceeds the fair value. CMS Energy and Consumers estimate the fair value of the asset using quoted market prices, market prices of similar assets, or discounted future cash flow analyses.

Impairment of Equity Method Investments

CMS Energy also assesses equity method investments for impairment whenever there has been a decline in value that is other than temporary. This assessment requires CMS Energy to determine the fair value of the equity method investment. CMS Energy determines fair value using valuation methodologies, including discounted cash flows, and assesses the ability of the investee to sustain an earnings capacity that justifies the carrying amount of the investment. CMS Energy records an impairment if the fair value is less than the carrying amount and the decline in value is considered to be other than temporary.

For additional details, see Note 20, Asset Sales, Discontinued Operations, and Impairment Charges.

Inventory - Gas and Coal

Inventory: CMS Energy and Consumers use the weighted-average cost method for valuing working gas, recoverable base gas in underground storage facilities, and materials and supplies inventory. CMS Energy and Consumers also use this method for valuing coal inventory, and they classify these amounts as generating plant fuel stock on their consolidated balance sheets.

Inventory - RECs and Emission Allowances

CMS Energy and Consumers classify RECs and emission allowances as materials and supplies inventory and use the weighted average method to remove amounts from inventory. RECs and emission allowances are used to satisfy compliance obligations related to the generation of power.

Inventory - Impairment

CMS Energy and Consumers use the lower-of-cost-or-market method to evaluate inventory for impairment.

Accounting for MISO Transactions

MISO Transactions: MISO requires the submission of hourly day-ahead and real-time bids and offers for energy at locations across the MISO region. Consumers and CMS ERM account for MISO transactions on a net hourly basis in each of the real-time and day-ahead markets, and they net transactions across all MISO energy market locations. CMS Energy and Consumers record net purchases in a single hour in purchased and interchange power and net sales in a single hour in operating revenue on the consolidated statements of income. They record net sale billing adjustments upon invoice receipt, record expense accruals for future net purchases adjustments based on historical experience, and reconcile accruals to actual expenses upon invoice receipt.

Property Taxes

Property Taxes: Property taxes are based on the taxable value of Consumers' real and personal property assessed by local taxing authorities. Consumers records property tax expense over the fiscal year of the taxing authority for which the taxes are levied based on Consumers' budgeted customer sales. The deferred property tax balance represents the amount of Consumers' accrued property tax that will be recognized over future governmental fiscal periods.

Restricted Cash and Cash Equivalents

Restricted Cash and Cash Equivalents: CMS Energy and Consumers have restricted cash and cash equivalents dedicated for repayment of Securitization bonds and for payment under performance guarantees. CMS Energy and Consumers classify these amounts as a current asset if they relate to payments that could or will occur within one year.

Consumers Energy Company [Member]

Corporate Structure

Principles of Consolidation

Use of Estimates

Use of Estimates: CMS Energy and Consumers are required to make estimates using assumptions that may affect reported amounts and disclosures. Actual results could differ from those estimates.

Revenue Recognition Policy - General

Revenue Recognition Policy - Alternative-Revenue Programs

Alternative-Revenue Programs: Under electric and gas rate cases orders issued by the MPSC in 2009 and 2010, Consumers was granted authority to implement revenue decoupling mechanisms. The electric revenue decoupling mechanism adjusts customer rates to collect or refund the change in marginal revenue arising from the difference between the level of average sales per customer adopted in the electric rate case order and actual average sales per customer. The gas revenue decoupling mechanism is similar, but does not adjust customer rates for changes in sales volumes resulting from weather fluctuations. Consumers accounts for these programs as alternative-revenue programs that meet the criteria for recognizing the effects of decoupling adjustments on revenue as electricity and gas are delivered. For details on Consumers' decoupling mechanisms, see Note 6, Regulatory Matters.

In September 2009, the MPSC approved an energy optimization incentive mechanism that provides a financial incentive if the energy savings of the Consumers' customers exceed annual targets established by the MPSC. Consumers accounts for this program as an alternative-revenue program that meets the criteria for recognizing revenue related to the incentive as soon as energy savings exceed the annual targets established by the MPSC.

Revenue Recognition Policy - Self-Implemented Rates

Self-Implemented Rates: Unless prohibited by the MPSC upon a showing of good cause, Consumers is allowed to self-implement new energy rates six months after a new rate case filing if the MPSC has not issued an order in the case. The MPSC then has another six months to issue a final order. If the MPSC does not issue a final order within that period, the filed rates are considered approved. If the MPSC issues a final order within that period, the rates that Consumers self-implemented may be subject to refund, with interest. Consumers recognizes revenue associated with self-implemented rates. If Consumers considers it probable that it will be required to refund a portion of its self-implemented rates, then Consumers records a provision for revenue subject to refund. For details on Consumers' self-implemented rates, see Note 6, Regulatory Matters.

Accounts Receivable

Cash and Cash Equivalents

Cash and Cash Equivalents: Cash and cash equivalents include short-term, highly liquid investments with original maturities of three months or less.

Contingencies

Contingencies: CMS Energy and Consumers record estimated liabilities for contingencies on their consolidated financial statements when it is probable that a liability has been incurred and when the amount of loss can be reasonably estimated. CMS Energy and Consumers expense legal fees as incurred; fees incurred but not yet billed are accrued based on estimates of work performed. This policy also applies to any fees incurred on behalf of employees and officers under indemnification agreements; such fees are billed directly to CMS Energy or Consumers.

Debt Issuance Costs, Discounts, Premiums, and Refinancing Costs

Derivative Instruments

Determination of Pension and OPEB MRV of Plan Assets

Financial Instruments

Impairment of Long-Lived Assets

Inventory - Gas and Coal

Inventory - RECs and Emission Allowances

Inventory - Impairment

CMS Energy and Consumers use the lower-of-cost-or-market method to evaluate inventory for impairment.

Accounting for MISO Transactions

Property Taxes

Restricted Cash and Cash Equivalents