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Summary of Significant Accounting Policies | 12 Months Ended
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Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract] |
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] | Summary of Significant Accounting Policies Organization OGE Energy is a holding company with investments in energy and energy services providers offering physical delivery and related services for both electricity and natural gas primarily in the south central U.S. OGE Energy conducts these activities through two business segments: (i) electric utility and (ii) natural gas midstream operations. The accounts of OGE Energy and its wholly-owned subsidiaries, including OG&E, are included in OGE Energy's consolidated financial statements. All intercompany transactions and balances are eliminated in such consolidation. OGE Energy generally uses the equity method of accounting for investments where its ownership interest is between 20 percent and 50 percent and it lacks the power to direct activities that most significantly impact economic performance. OG&E. OGE Energy's electric utility operations are conducted through OG&E, which generates, transmits, distributes and sells electric energy in Oklahoma and western Arkansas. OG&E's rates are subject to regulation by the OCC, the APSC and the FERC. OG&E was incorporated in 1902 under the laws of the Oklahoma Territory and is a wholly-owned subsidiary of OGE Energy. OG&E is the largest electric utility in Oklahoma, and its franchised service territory includes Fort Smith, Arkansas and the surrounding communities. OG&E sold its retail natural gas business in 1928 and is no longer engaged in the natural gas distribution business. Enable. OGE Energy's natural gas midstream operations segment represents OGE Energy's investment in Enable. The investment in Enable is held through wholly-owned subsidiaries and ultimately OGE Holdings. Enable is primarily engaged in the business of gathering, processing, transporting and storing natural gas. Enable's natural gas gathering and processing assets are strategically located in four states and serve natural gas production in the Anadarko, Arkoma and Ark-La-Tex Basins. Enable also owns crude oil gathering assets in the Anadarko and Williston Basins. Enable has intrastate natural gas transportation and storage assets that are located in Oklahoma as well as interstate assets that extend from western Oklahoma and the Texas Panhandle to Louisiana, from Louisiana to Illinois and from Louisiana to Alabama. Enable's general partner is equally controlled by OGE Energy and CenterPoint, who each have 50 percent management ownership. Based on the 50/50 management ownership, with neither company having control, OGE Energy accounts for its interest in Enable using the equity method of accounting. In February 2021, Enable entered into a definitive merger agreement with Energy Transfer. For further discussion, see Note 5. OGE Energy charges operating costs to OG&E and Enable based on several factors. Operating costs directly related to OG&E and Enable are assigned as such. Operating costs incurred for the benefit of OG&E and Enable are allocated either as overhead based primarily on labor costs or using the "Distrigas" method. The "Distrigas" method is a three-factor formula that uses an equal weighting of payroll, net operating revenues and gross property, plant and equipment. OGE Energy adopted this method as a result of a recommendation by the OCC Staff. OGE Energy believes this method provides a reasonable basis for allocating common expenses. Use of Estimates In preparing the financial statements, management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and contingent liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Changes to these assumptions and estimates could have a material effect on the Registrants' financial statements. However, the Registrants believe they have taken reasonable positions where assumptions and estimates are used in order to minimize the negative financial impact to the Registrants that could result if actual results vary from the assumptions and estimates. In management's opinion, the areas where the most significant judgment is exercised include the determination of Pension Plan assumptions, income taxes, contingency reserves, asset retirement obligations, regulatory assets and liabilities, unbilled revenues and the allowance for uncollectible accounts receivable. For OGE Energy, significant judgment is also exercised in the determination of any impairment of equity method investments. Cash and Cash Equivalents For purposes of the financial statements, the Registrants consider all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. These investments are carried at cost, which approximates fair value. Allowance for Uncollectible Accounts Receivable Customer balances are generally written off if not collected within six months after the final billing date. The allowance for uncollectible accounts receivable for OG&E is generally calculated by multiplying the last six months of electric revenue by the provision rate, which is based on a 12-month historical average of actual balances written off and is adjusted for current conditions and supportable forecasts as necessary. To the extent the historical collection rates, when incorporating forecasted conditions, are not representative of future collections, there could be an effect on the amount of uncollectible expense recognized, such as in response to COVID-19 impacts. Also, a portion of the uncollectible provision related to fuel within the Oklahoma jurisdiction is being recovered through the fuel adjustment clause. The allowance for uncollectible accounts receivable is a reduction to Accounts Receivable in the balance sheets and is included in Other Operation and Maintenance Expense in the statements of income. The allowance for uncollectible accounts receivable was $2.6 million and $1.5 million at December 31, 2020 and 2019, respectively. New business customers are required to provide a security deposit in the form of cash, bond or irrevocable letter of credit that is refunded when the account is closed. New residential customers whose outside credit scores indicate an elevated risk are required to provide a security deposit that is refunded based on customer protection rules defined by the OCC and the APSC. The payment behavior of all existing customers is continuously monitored, and, if the payment behavior indicates sufficient risk within the meaning of the applicable utility regulation, customers will be required to provide a security deposit. The Registrants considered COVID-19 pandemic impacts when calculating their reserve on accounts receivable as of December 31, 2020, as further discussed within "Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations - Recent Developments." Investment in Unconsolidated Affiliates OGE Energy's investment in Enable is considered to be a variable interest entity because the owners of the equity at risk in this entity have disproportionate voting rights in relation to their obligations to absorb the entity's expected losses or to receive its expected residual returns. However, OGE Energy is not considered the primary beneficiary of Enable since it does not have the power to direct the activities of Enable that are considered most significant to the economic performance of Enable; therefore, OGE Energy accounts for its investment in Enable using the equity method of accounting. Under the equity method, the investment will be adjusted each period for contributions made, distributions received and OGE Energy's share of the investee's comprehensive income as adjusted for basis differences. OGE Energy's maximum exposure to loss related to Enable is limited to its equity investment in Enable at December 31, 2020 as presented in Note 14. OGE Energy evaluates its equity method investments for impairment when events or changes in circumstances indicate there is a loss in value of the investment that is other than a temporary decline. When indicators exist, the fair value is estimated and compared to the investment carrying value, and if any impairment is judgmentally determined to be other than temporary, the carrying value of the investment is written down to fair value. OGE Energy determined, effective March 31, 2020, that an other than temporary decline in the value of OGE Energy's investment in Enable had occurred. Further information detailing the results of OGE Energy's impairment analysis and fair value measurement can be found in Notes 5 and 7, respectively. OGE Energy considers distributions received from Enable which do not exceed cumulative equity in earnings subsequent to the date of investment to be a return on investment and are classified as operating activities in the statements of cash flows. OGE Energy considers distributions received from Enable in excess of cumulative equity in earnings subsequent to the date of investment to be a return of investment and are classified as investing activities in the statements of cash flows. Allowance for Funds Used During Construction Allowance for funds used during construction, a non-cash item, is reflected as an increase to Net Other Income and a reduction to Interest Expense in the statements of income and as an increase to Construction Work in Progress in the balance sheets. Allowance for funds used during construction is calculated according to the FERC requirements for the imputed cost of equity and borrowed funds. Allowance for funds used during construction rates, compounded semi-annually, were 7.3 percent, 7.6 percent and 7.6 percent for the years ended December 31, 2020, 2019 and 2018, respectively. Collection of Sales Tax In the normal course of its operations, OG&E collects sales tax from its customers. OG&E records a current liability for sales taxes when it bills its customers and eliminates this liability when the taxes are remitted to the appropriate governmental authorities. OG&E excludes the sales tax collected from its operating revenues. Revenue Recognition General OG&E recognizes revenue from electric sales when power is delivered to customers. The performance obligation to deliver electricity is generally created and satisfied simultaneously, and the provisions of the regulatory-approved tariff determine the charges OG&E may bill the customer, payment due date and other pertinent rights and obligations of both parties. OG&E measures its customers' metered usage and sends bills to its customers throughout each month. As a result, there is a significant amount of customers' electricity consumption that has not been billed at the end of each month. OG&E accrues an estimate of the revenues for electric sales delivered since the latest billings. Unbilled revenue is presented in Accrued Unbilled Revenues in the balance sheets and in Revenues from Contracts with Customers in the statements of income based on estimates of usage and prices during the period. The estimates that management uses in this calculation could vary from the actual amounts to be paid by customers. Integrated Market and Transmission OG&E currently owns and operates transmission and generation facilities as part of a vertically integrated utility. OG&E is a member of the SPP regional transmission organization and has transferred operational authority, but not ownership, of OG&E's transmission facilities to the SPP. The SPP has implemented FERC-approved regional day-ahead and real-time markets for energy and operating services, as well as associated transmission congestion rights. Collectively, the three markets operate together under the global name, SPP Integrated Marketplace. OG&E represents owned and contracted generation assets and customer load in the SPP Integrated Marketplace for the sole benefit of its customers. OG&E has not participated in the SPP Integrated Marketplace for any speculative trading activities. OG&E records the SPP Integrated Marketplace transactions as sales or purchases per FERC Order 668, which requires that purchases and sales be recorded on a net basis for each settlement period of the SPP Integrated Marketplace. Purchases and sales are based on the fixed transaction price determined by the market at the time of the purchase or sale and the MWh quantity purchased or sold. These results are reported as Revenues from Contracts with Customers or Cost of Sales in the statements of income. OG&E revenues, expenses, assets and liabilities may be adversely affected by changes in the organization, operating and regulation by the FERC or the SPP. OG&E's transmission revenues are generated by the use of OG&E's transmission network by the SPP, which operates the network, on behalf of other transmission owners. OG&E recognizes revenue on the sale of transmission service to its customers over time as the service is provided in the amount OG&E has a right to invoice. Transmission service to the SPP is billed monthly based on a fixed transaction price determined by OG&E's FERC-approved formula transmission rates along with other SPP-specific charges and the megawatt quantity reserved. Other Revenues Other Revenues in the statements of income is comprised of certain rider revenue that includes alternative revenue measures as defined in ASC 980, "Regulated Operations," which details two types of alternative revenue programs. The first type adjusts billings for the effects of weather abnormalities or broad external factors or to compensate OG&E for demand-side management initiatives (i.e., no-growth plans and similar conservation efforts). The second type provides for additional billings (i.e., incentive awards) for the achievement of certain objectives, such as reducing costs, reaching specified milestones or demonstratively improving customer service. Once the specific events permitting billing of the additional revenues under either program type have been completed, OG&E recognizes the additional revenues if (i) the program is established by an order from OG&E's regulatory commission that allows for automatic adjustment of future rates; (ii) the amount of additional revenues for the period is objectively determinable and is probable of recovery; and (iii) the additional revenues will be collected within 24 months following the end of the annual period in which they are recognized. Fuel Adjustment Clauses The actual cost of fuel used in electric generation and certain purchased power costs are passed through to OG&E's customers through fuel adjustment clauses. The fuel adjustment clauses are subject to periodic review by the OCC and the APSC. LeasesThe Registrants evaluate all contracts under ASC 842 to determine if the contract is or contains a lease and to determine classification as an operating or finance lease. If a lease is identified, the Registrants recognize a right-of-use asset and a lease liability in their balance sheets. The Registrants recognize and measure a lease liability when they conclude the contract contains an identified asset that the Registrants control through having the right to obtain substantially all of the economic benefits and the right to direct the use of the identified asset. The liability is equal to the present value of lease payments, and the asset is based on the liability, subject to adjustment, such as for initial direct costs. Further, the Registrants utilize an incremental borrowing rate for purposes of measuring lease liabilities, if the discount rate is not implicit in the lease. To calculate the incremental borrowing rate, the Registrants start with a current pricing report for their senior unsecured notes, which indicates rates for periods reflective of the lease term, and adjust for the effects of collateral to arrive at the secured incremental borrowing rate. As permitted by ASC 842, the Registrants made an accounting policy election to not apply the balance sheet recognition requirements to short-term leases and to not separate lease components from non-lease components when recognizing and measuring lease liabilities. For income statement purposes, the Registrants record operating lease expense on a straight-line basis. Income Taxes OGE Energy files consolidated income tax returns in the U.S. federal jurisdiction and various state jurisdictions. OG&E is a part of the consolidated tax return of OGE Energy. Income taxes are generally allocated to each company in the affiliated group, including OG&E, based on its stand-alone taxable income or loss. Federal investment tax credits previously claimed on electric utility property have been deferred and will be amortized to income over the life of the related property. The Registrants use the asset and liability method of accounting for income taxes. Under this method, a deferred tax asset or liability is recognized for the estimated future tax effects attributable to temporary differences between the financial statement basis and the tax basis of assets and liabilities as well as tax credit carry forwards and net operating loss carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period of the change. The Registrants recognize interest related to unrecognized tax benefits in Interest Expense and recognize penalties in Other Expense in the statements of income. Accrued Vacation The Registrants accrue vacation pay monthly by establishing a liability for vacation earned. Vacation may be taken as earned and is charged against the liability. At the end of each year, the liability represents the amount of vacation earned but not taken.
Comprehensive Income (Loss) Note [Text Block] | Accumulated Other Comprehensive Income (Loss) The following table presents changes in the components of accumulated other comprehensive income (loss) attributable to OGE Energy during 2019 and 2020. All amounts below are presented net of tax.
| Pension Plan and Restoration of Retirement Income Plan |  |  |  | Postretirement Benefit Plans |  |
(In millions) | Net Gain (Loss) |  |  |  | Net Gain (Loss) | Prior Service Cost (Credit) | Other Comprehensive Loss from Unconsolidated Affiliates | Total
Balance at December 31, 2018 | $ | (38.8) |  |  |  |  | $ | 4.6 |  | $ | 5.3 |  | $ | — |  | $ | (28.9) |
Other comprehensive loss before reclassifications | (8.3) |  |  |  |  | (0.2) |  | — |  | (0.6) |  | (9.1) |
Amounts reclassified from accumulated other comprehensive income (loss) | 3.4 |  |  |  |  | (0.2) |  | (1.7) |  | — |  | 1.5 |
Settlement cost | 8.6 |  |  |  |  | — |  | — |  | — |  | 8.6 |
Net current period other comprehensive income (loss) | 3.7 |  |  |  |  | (0.4) |  | (1.7) |  | (0.6) |  | 1.0 |
Balance at December 31, 2019 | (35.1) |  |  |  |  | 4.2 |  | 3.6 |  | (0.6) |  | (27.9) |
Other comprehensive income (loss) before reclassifications | (5.1) |  |  |  |  | (2.4) |  | — |  | (0.7) |  | (8.2) |
Amounts reclassified from accumulated other comprehensive income (loss) | 3.9 |  |  |  |  | (0.1) |  | (1.7) |  | — |  | 2.1 |
Curtailment cost | — |  |  |  |  | (0.3) |  | — |  | — |  | (0.3) |
Settlement cost | 2.2 |  |  |  |  | — |  | — |  | — |  | 2.2 |
Net current period other comprehensive income (loss) | 1.0 |  |  |  |  | (2.8) |  | (1.7) |  | (0.7) |  | (4.2) |
Balance at December 31, 2020 | $ | (34.1) |  |  |  |  | $ | 1.4 |  | $ | 1.9 |  | $ | (1.3) |  | $ | (32.1) |
The following table presents significant amounts reclassified out of accumulated other comprehensive income (loss) by the respective line items in net income (loss) during the years ended December 31, 2020 and 2019.
Details about Accumulated Other Comprehensive Income (Loss) Components | Amount Reclassified from Accumulated Other Comprehensive Income (Loss) | Affected Line Item in OGE Energy's Statements of Income
| Year Ended December 31, |
(In millions) | 2020 | 2019 |
Amortization of Pension Plan and Restoration of Retirement Income Plan items: |  |  |
Actuarial losses | $ | (5.1) |  | $ | (4.5) |  | (A)
Settlement cost | (2.9) |  | (11.3) |  | (A)
| (8.0) |  | (15.8) |  | Income (Loss) Before Taxes
| (1.9) |  | (3.8) |  | Income Tax Expense (Benefit)
| $ | (6.1) |  | $ | (12.0) |  | Net Income (Loss)
Amortization of postretirement benefit plans items: |  |  |
Prior service credit | $ | 2.3 |  | $ | 2.3 |  | (A)
Curtailment cost | 0.4 |  | — |  | (A)
Actuarial gains | 0.1 |  | 0.2 |  | (A)
| 2.8 |  | 2.5 |  | Income (Loss) Before Taxes
| 0.7 |  | 0.6 |  | Income Tax Expense (Benefit)
| $ | 2.1 |  | $ | 1.9 |  | Net Income (Loss)
Total reclassifications for the period, net of tax | $ | (4.0) |  | $ | (10.1) |  | Net Income (Loss)
(A)These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost (see Note 13 for additional information).
Asset Retirement Obligation Disclosure [Text Block] | OG&E has asset retirement obligations primarily associated with the removal of company-owned wind turbines on leased land, as well as the removal of asbestos from certain power generating stations. OG&E has recorded asset retirement obligations that are being accreted over their respective lives ranging from five to 68 years. Asset retirement obligations are included in Other Deferred Credits in the Registrants' balance sheets. The following table presents changes to OG&E's asset retirement obligations during the years ended December 31, 2020 and 2019.
(In millions) | 2020 | 2019
Balance at January 1 | $ | 73.5 |  | $ | 83.9 |
Accretion expense | 0.5 |  | 1.0 |
Revisions in estimated cash flows (A) | 5.8 |  | (2.4) |
Liabilities settled (B) | (0.2) |  | (9.0) |
Balance at December 31 | $ | 79.6 |  | $ | 73.5 |
(A)Assumptions changed related to the estimated timing and estimated cost of the removal of asbestos at OG&E's generating facilities. (B)Asset retirement obligations were settled for asbestos removal at one of OG&E's generating facilitiesAccruals for environmental costs are recognized when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated. Costs are charged to expense or deferred as a regulatory asset based on expected recovery from customers in future rates, if they relate to the remediation of conditions caused by past operations or if they are not expected to mitigate or prevent contamination from future operations. Where environmental expenditures relate to facilities currently in use, such as pollution control equipment, the costs may be capitalized and depreciated over the future service periods. Estimated remediation costs are recorded at undiscounted amounts, independent of any insurance or rate recovery, based on prior experience, assessments and current technology. Accrued obligations are regularly adjusted as environmental assessments and estimates are revised and remediation efforts proceed. For sites where OG&E has been designated as one of several potentially responsible parties, the amount accrued represents OG&E's estimated share of the cost. OG&E had $25.0 million and $18.7 million in accrued environmental liabilities at December 31, 2020 and 2019, respectively, which are included in OG&E's asset retirement obligations.
Property, Plant and Equipment Disclosure [Text Block] | Property, Plant and Equipment All property, plant and equipment is recorded at cost. Newly constructed plant is added to plant balances at cost which includes contracted services, direct labor, materials, overhead, transportation costs and the allowance for funds used during construction. Replacements of units of property are capitalized as plant. For assets that belong to a common plant account, the replaced plant is removed from plant balances, and the cost of such property net of any salvage proceeds is charged to Accumulated Depreciation. For assets that do not belong to a common plant account, the replaced plant is removed from plant balances with the related accumulated depreciation, and the remaining balance net of any salvage proceeds is recorded as a loss in the statements of income as Other Expense. Repair and replacement of minor items of property are included in the statements of income as Other Operation and Maintenance Expense. The following tables present OG&E's ownership interest in the jointly-owned McClain Plant and the jointly-owned Redbud Plant, and, as disclosed below, only OG&E's ownership interest is reflected in the property, plant and equipment and accumulated depreciation balances in these tables. The owners of the remaining interests in the McClain Plant and the Redbud Plant are responsible for providing their own financing of capital expenditures. Also, only OG&E's proportionate interests of any direct expenses of the McClain Plant and the Redbud Plant, such as fuel, maintenance expense and other operating expenses, are included in the applicable financial statement captions in the statements of income.
December 31, 2020 (In millions) | Percentage Ownership | Total Property, Plant and Equipment | Accumulated Depreciation | Net Property, Plant and Equipment
McClain Plant (A) | 77 | % | $ | 257.1 |  | $ | 96.0 |  | $ | 161.1 |
Redbud Plant (A)(B) | 51 | % | $ | 531.8 |  | $ | 181.9 |  | $ | 349.9 |
(A)Construction work in progress was $0.1 million and $1.8 million for the McClain and Redbud Plants, respectively. (B)This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $67.3 million.
December 31, 2019 (In millions) | Percentage Ownership | Total Property, Plant and Equipment | Accumulated Depreciation | Net Property, Plant and Equipment
McClain Plant (A) | 77 | % | $ | 254.4 |  | $ | 83.5 |  | $ | 170.9 |
Redbud Plant (A)(B) | 51 | % | $ | 529.9 |  | $ | 159.0 |  | $ | 370.9 |
(A)Construction work in progress was $0.2 million and $1.4 million for the McClain and Redbud Plants, respectively. (B)This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $61.8 million. The following tables present the Registrants' major classes of property, plant and equipment and related accumulated depreciation.
December 31, 2020 (In millions) | Total Property, Plant and Equipment | Accumulated Depreciation | Net Property, Plant and Equipment
OG&E: |  |  |
Distribution assets | $ | 4,809.9 |  | $ | 1,422.1 |  | $ | 3,387.8 |
Electric generation assets (A) | 4,932.2 |  | 1,713.6 |  | 3,218.6 |
Transmission assets (B) | 2,944.6 |  | 591.7 |  | 2,352.9 |
Intangible plant | 254.1 |  | 153.9 |  | 100.2 |
Other property and equipment | 495.3 |  | 186.3 |  | 309.0 |
OG&E property, plant and equipment | 13,436.1 |  | 4,067.6 |  | 9,368.5 |
Non-OG&E property, plant and equipment | 6.1 |  | — |  | 6.1 |
Total OGE Energy property, plant and equipment | $ | 13,442.2 |  | $ | 4,067.6 |  | $ | 9,374.6 |
(A)This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $67.3 million. (B)This amount includes a plant acquisition adjustment of $3.3 million and accumulated amortization of $0.9 million.
December 31, 2019 (In millions) | Total Property, Plant and Equipment | Accumulated Depreciation | Net Property, Plant and Equipment
OG&E: |  |  |
Distribution assets | $ | 4,468.6 |  | $ | 1,381.1 |  | $ | 3,087.5 |
Electric generation assets (A) | 4,838.6 |  | 1,601.0 |  | 3,237.6 |
Transmission assets (B) | 2,901.1 |  | 565.5 |  | 2,335.6 |
Intangible plant | 225.2 |  | 145.4 |  | 79.8 |
Other property and equipment | 473.1 |  | 175.1 |  | 298.0 |
OG&E property, plant and equipment | 12,906.6 |  | 3,868.1 |  | 9,038.5 |
Non-OG&E property, plant and equipment | 6.1 |  | — |  | 6.1 |
Total OGE Energy property, plant and equipment | $ | 12,912.7 |  | $ | 3,868.1 |  | $ | 9,044.6 |
(A)This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $61.8 million. (B)This amount includes a plant acquisition adjustment of $3.3 million and accumulated amortization of $0.8 million. OG&E's unamortized computer software costs, included in intangible plant above, were $89.7 million and $71.3 million at December 31, 2020 and 2019, respectively. OG&E's amortization expense for computer software costs was $14.9 million, $11.0 million and $9.6 million for the years ended December 31, 2020, 2019 and 2018, respectively. Depreciation and Amortization The provision for depreciation, which was 2.6 percent and 2.7 percent of the average depreciable utility plant for 2020 and 2019, respectively, is calculated using the straight-line method over the estimated service life of the utility assets. Depreciation is provided at the unit level for production plant and at the account or sub-account level for all other plant and is based on the average life group method. In 2021, the provision for depreciation is projected to be 2.6 percent of the average depreciable utility plant. Amortization of intangible assets is calculated using the straight-line method. Of the remaining amortizable intangible plant balance at December 31, 2020, 99.0 percent will be amortized over 10.4 years with the remaining 1.0 percent of the intangible plant balance at December 31, 2020 being amortized over 23.7 years. Amortization of plant acquisition adjustments is provided on a straight-line basis over the estimated remaining service life of the acquired assets. Plant acquisition adjustments include $148.3 million for the Redbud Plant, which is being amortized over a 27 year life, and $3.3 million for certain transmission substation facilities in OG&E's service territory, which is being amortized over a 37 to 59 year period.
Inventory Disclosure [Text Block] | Fuel Inventories Fuel inventories for the generation of electricity consist of coal, natural gas and oil. OG&E uses the weighted-average cost method of accounting for inventory that is physically added to or withdrawn from storage or stockpiles. The amount of fuel inventory was $36.5 million and $46.3 million at December 31, 2020 and 2019, respectively.
Summary of Significant Accounting Policies [Text Block] | Accounting Records The accounting records of OG&E are maintained in accordance with the Uniform System of Accounts prescribed by the FERC and adopted by the OCC and the APSC. Additionally, OG&E, as a regulated utility, is subject to accounting principles for certain types of rate-regulated activities, which provide that certain incurred costs that would otherwise be charged to expense can be deferred as regulatory assets, based on the expected recovery from customers in future rates. Likewise, certain actual or anticipated credits that would otherwise reduce expense can be deferred as regulatory liabilities, based on the expected flowback to customers in future rates. Management's expected recovery of deferred costs and flowback of deferred credits generally results from specific decisions by regulators granting such ratemaking treatment. OG&E records certain incurred costs and obligations as regulatory assets or liabilities if, based on regulatory orders or other available evidence, it is probable that the costs or obligations will be included in amounts allowable for recovery or refund in future rates. The following table presents a summary of OG&E's regulatory assets and liabilities.
December 31 (In millions) | 2020 | 2019
REGULATORY ASSETS |  |
Current: |  |
SPP cost tracker under recovery (A) | $ | 7.0 |  | $ | — |
Generation Capacity Replacement rider under recovery (A) | 4.4 |  | 3.7 |
Fuel clause under recoveries | — |  | 39.5 |
Other (A) | 8.4 |  | 5.5 |
Total current regulatory assets | $ | 19.8 |  | $ | 48.7 |
Non-current: |  |
Benefit obligations regulatory asset | $ | 164.9 |  | $ | 167.2 |
Deferred storm expenses | 158.8 |  | 65.5 |
Sooner Dry Scrubbers | 19.7 |  | 20.6 |
Pension tracker | 18.1 |  | 2.3 |
Smart Grid | 11.2 |  | 18.4 |
Unamortized loss on reacquired debt | 9.7 |  | 10.6 |
Arkansas deferred pension expenses | 9.3 |  | 8.0 |
Frontier Plant deferred expenses | 6.4 |  | — |
COVID-19 impacts | 6.4 |  | — |
Other | 11.1 |  | 13.4 |
Total non-current regulatory assets | $ | 415.6 |  | $ | 306.0 |
REGULATORY LIABILITIES |  |
Current: |  |
Fuel clause over recoveries | $ | 28.6 |  | $ | 4.8 |
Oklahoma demand program rider over recovery (B) | 1.5 |  | 2.0 |
Reserve for tax refund and interim surcharge (B) | 0.8 |  | 12.7 |
SPP cost tracker over recovery (B) | — |  | 2.6 |
Other (B) | 4.2 |  | 6.9 |
Total current regulatory liabilities | $ | 35.1 |  | $ | 29.0 |
Non-current: |  |
Income taxes refundable to customers, net | $ | 867.4 |  | $ | 899.2 |
Accrued removal obligations, net | 316.8 |  | 318.5 |
Other | 4.7 |  | 5.8 |
Total non-current regulatory liabilities | $ | 1,188.9 |  | $ | 1,223.5 |
(A)Included in Other Current Assets in the balance sheets. (B)Included in Other Current Liabilities in the balance sheets. OG&E recovers certain SPP costs related to base plan charges from its customers and refunds certain SPP revenues received to its customers in Oklahoma through the SPP cost tracker and in Arkansas through the transmission cost recovery rider. OG&E recovers the Oklahoma jurisdictional portion of costs, including non-fuel operation and maintenance expenses, depreciation, taxes other than income taxes and a return on capital, for its investment in the River Valley plant through the Generation Capacity Replacement Rider. The OCC also authorized OG&E to defer the same costs related to its investment in the Frontier plant to a regulatory asset, and recovery of these costs will be considered in future rate proceedings. Fuel clause under and over recoveries are generated from OG&E's customers when OG&E's cost of fuel either exceeds or is less than the amount billed to its customers, respectively. OG&E's fuel recovery clauses are designed to smooth the impact of fuel price volatility on customers' bills. As a result, OG&E under recovers fuel costs in periods of rising fuel prices above the baseline charge for fuel and over recovers fuel costs when prices decline below the baseline charge for fuel. Provisions in the fuel clauses are intended to allow OG&E to amortize under and over recovery balances. The benefit obligations regulatory asset is comprised of expenses recorded which are probable of future recovery and that have not yet been recognized as components of net periodic benefit cost, including net loss and prior service cost. These expenses are recorded as a regulatory asset as OG&E historically has recovered and currently recovers pension and postretirement benefit plan expense in its electric rates. If, in the future, the regulatory bodies indicate a change in policy related to the recovery of pension and postretirement benefit plan expenses, this could cause the benefit obligations regulatory asset balance to be reclassified to accumulated other comprehensive income. The following table presents a summary of the components of the benefit obligations regulatory asset.
December 31 (In millions) | 2020 | 2019
Pension Plan and Restoration of Retirement Income Plan: |  |
Net loss | $ | 147.3 |  | $ | 160.5 |
Postretirement Benefit Plans: |  |
Net loss | 26.2 |  | 23.3 |
Prior service cost | (8.6) |  | (16.6) |
Total | $ | 164.9 |  | $ | 167.2 |
OG&E includes in expense any Oklahoma storm-related operation and maintenance expenses up to $2.7 million annually and defers to a regulatory asset any additional expenses incurred over $2.7 million. OG&E expects to recover the amounts deferred each year over a five-year period in accordance with historical practice. As approved by the OCC, OG&E deferred the non-fuel incremental operation and maintenance expenses, depreciation, debt cost associated with the capital investment and related ad valorem taxes for the Dry Scrubbers at Sooner Units 1 and 2 as a regulatory asset, and these costs are being recovered over 25 years. OG&E recovers specific amounts of pension and postretirement medical costs in rates approved in its Oklahoma rate reviews. In accordance with approved orders, OG&E defers the difference between actual pension and postretirement medical expenses and the amount approved in its last Oklahoma rate review as a regulatory asset or regulatory liability. These amounts have been recorded in the Pension tracker regulatory asset in the table above. OG&E deferred to a regulatory asset the incremental and stranded costs that were accumulated during Smart Grid deployment, including (i) costs for web portal access, (ii) costs for education and home energy reports and (iii) stranded costs associated with OG&E's analog electric meters, which have been replaced by smart meters. As approved by the OCC and APSC, these costs are being recovered over a six-year period ending in 2022 in Oklahoma and 2023 in Arkansas. Unamortized loss on reacquired debt is comprised of unamortized debt issuance costs related to the early retirement of OG&E's long-term debt. These amounts are recorded in interest expense and are being amortized over the term of the long-term debt which replaced the previous long-term debt. The unamortized loss on reacquired debt is recovered as a part of OG&E's cost of capital. Arkansas includes a certain level of pension expense in base rates. When the Pension Plan experiences a settlement, which represents an acceleration of future pension costs, OG&E defers to a regulatory asset the Arkansas jurisdictional portion of each settlement, which historically has been recovered from customers over the average life of the remaining plan participants. A portion of these settlements is being recovered in current rates, and recovery of additional amounts will be requested as additional settlements occur. For additional information related to settlements, see Note 13. In response to the COVID-19 pandemic, the OCC and APSC issued orders allowing OG&E to defer certain expenses related to its COVID-19 response. For additional information about these orders, see Note 16 and "Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations - Recent Developments." OG&E recovers program costs related to the Demand and Energy Efficiency Program in Oklahoma through the Demand Program Rider, which operates on a three-year program cycle. The current program cycle, which runs through 2021, includes recovery of (i) energy efficiency program costs, (ii) lost revenues associated with certain achieved energy efficiency and demand savings, (iii) performance-based incentives and (iv) costs associated with research and development investments. As a result of filings with the OCC, APSC and FERC, OG&E established mechanisms to refund to customers the amount of excess taxes received through rates, with an ongoing adjustment for any excess accumulated deferred income taxes resulting from the Tax Cuts and Jobs Act of 2017. Additional amounts due to customers will be refunded in accordance with agreements in each jurisdiction. Income taxes refundable to customers, net, represents the reduction in accumulated deferred income taxes resulting from the reduction in the federal income tax rate as part of the Tax Cuts and Jobs Act of 2017 and includes income taxes recoverable from customers that represent income tax benefits previously used to reduce OG&E's revenues (treated as regulatory assets). These liabilities will be returned to customers in varying amounts over approximately 80 years, and the assets will be amortized over the estimated remaining life of the assets to which they relate, as the temporary differences that generated the income tax benefits turn around. Accrued removal obligations, net represents asset retirement costs previously recovered from ratepayers for other than legal obligations. Management continuously monitors the future recoverability of regulatory assets. When in management's judgment future recovery becomes impaired, the amount of the regulatory asset is adjusted, as appropriate. If OG&E were required to discontinue the application of accounting principles for certain types of rate-regulated activities for some or all of its operations, it could result in writing off the related regulatory assets or liabilities, which could have significant financial effects.
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