Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2015

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Summary of Significant Accounting Policies [Text Block]

Summary of Significant Accounting Policies

Organization

The Company is an energy and energy services provider offering physical delivery and related services for both electricity and natural gas primarily in the south central United States. The Company conducts these activities through two business segments: (i) electric utility and (ii) natural gas midstream operations. The accounts of the Company and its wholly owned subsidiaries are included in the consolidated financial statements. All intercompany transactions and balances are eliminated in consolidation. The Company generally uses the equity method of accounting for investments where its ownership interest is between 20 percent and 50 percent and has the ability to exercise significant influence.

The electric utility segmentgenerates, transmits, distributes and sells electric energy in Oklahoma and western Arkansas. Its operationsare conducted through OG&Eandare 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 the Company.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.

The natural gas midstream operations segment currently represents the Company's investment in Enable through its wholly owned subsidiary OGE Holdings. Enable is 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 from shale developments in the Anadarko, Arkoma and Ark-La-Tex basins. Enable also owns a crude oil gathering business in the Bakken shale formation, principally located in the Williston basin of North Dakota. Enable's natural gas transportation and storage assets extend from western Oklahoma and the Texas Panhandle to Alabama and from Louisiana to Illinois. For periods prior to the formation of Enable, the natural gas midstream operations segment reflected the consolidated results of Enogex Holdings. All significant intercompany transactions have been eliminated in consolidation.

Enable was formed effective May 1, 2013by the Company, the ArcLight group and CenterPoint to own and operate the midstream businesses of the Company and CenterPoint. In the formation transaction, the Company and the ArcLight group contributed Enogex LLC to Enable andthe Company deconsolidated its previously held investment in Enogex Holdings and acquired an equity interest in Enable.The Company's contribution of Enogex LLC to Enable met the requirements of being in substance real estate and was recorded at historical cost.The general partner of Enable is equally controlled by CenterPoint and OGE Energy, who each have50 percentmanagement ownership.Based on the 50/50 management ownership, with neither company having control, effective May 1, 2013, the Companybegan accounting for its interest in Enable using the equity method of accounting.

In April 2014, Enable completed an initial public offering of25,000,000common units resulting in Enable becoming a publicly traded Master Limited Partnership. At December 31, 2015, the Company owned approximately 111.0 million limited partner units, or 26.3 percent, of which 68.2 million limited partner units were subordinated.

On January 22, 2016, Enable announced a quarterly dividend distribution of$0.31800per unit on its outstanding common and subordinated units, which is unchanged from the previous quarter.Based on current commodity prices, Enable has seen changes in producer activity that have negatively impacted Enable's operations and financial position and could see additional changes in producer activity that may negatively impact Enable's operations and affect its future distribution rates.If cash distributions to Enable’s unitholders exceed$0.330625per unit in any quarter, the general partner will receive increasing percentages, up to50 percent, of the cash Enable distributes in excess of that amount. OGE Holdings is entitled to60 percentof those “incentive distributions.” In certain circumstances, the general partner has the right to reset the minimum quarterly distribution and the target distribution levels at which the incentive distributions receive increasing percentages to higher levels based on Enable’s cash distributions at the time of the exercise of this reset election.

The Company 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.  The Company adopted this method in January 1996 as a result of a recommendation by the OCC Staff. The Company believes this method provides a reasonable basis for allocating common expenses.

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.

Certain prior year amounts have been reclassified to conform with the current year presentation.

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 is a summary of OG&E's regulatory assets and liabilities at:

December 31 (In millions)	2015		2014
Regulatory Assets
Current
Oklahoma demand program rider under recovery (A)	$	36.6	$	19.7
Fuel clause under recoveries	—		68.3
Other (A)(B)	9.9		10.2
Total Current Regulatory Assets	$	46.5	$	98.2
Non-Current
Benefit obligations regulatory asset	$	242.2	$	261.1
Income taxes recoverable from customers, net	56.7		56.1
Smart Grid	43.6		43.9
Deferred storm expenses	27.6		17.5
Unamortized loss on reacquired debt	14.8		16.1
Other (B)	17.3		15.7
Total Non-Current Regulatory Assets	$	402.2	$	410.4
Regulatory Liabilities
Current
Fuel clause over recoveries	$	61.3	$	—
Crossroads wind farm rider over recovery (C)	2.9		10.3
Smart Grid rider over recovery (C)	2.0		12.5
Other (C)	2.6		1.6
Total Current Regulatory Liabilities	$	68.8	$	24.4
Non-Current
Accrued removal obligations, net	$	254.9	$	248.1
Pension tracker	17.7		14.9
Total Non-Current Regulatory Liabilities	$	272.6	$	263.0

(A) Included in Other Current Assets on the Consolidated Balance Sheets.

(B) Prior year amount of$1.1 millionreclassified from Non-Current Other assets to Current Other assets.

(C) Included in Other Current Liabilities on the Consolidated Balance Sheets.

Fuel clause under recoveries are generated from under recoveries from OG&E's customers when OG&E's cost of fuel exceeds the amount billed to its customers.  Fuel clause over recoveries are generated from over recoveries from OG&E's customers when the amount billed to its customers exceeds OG&E's cost of fuel.  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.

OG&E recovers program costs related to the Demand and Energy Efficiency Program. An extension of the demand program rider was approved in December 2012, which allowed for the recovery of demand program costs, lost revenues associated with certain achieved energy, demand savings and performance based incentives and the recovery of costs associated with research and development investments through December 2015.

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 had historically 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 is a summary of the components of the benefit obligations regulatory asset at:

December 31 (In millions)	2015			2014
Pension Plan and Restoration of Retirement Income Plan
Net loss	$	214.1		$	196.7
Prior service cost	—			0.6
Postretirement Benefit Plans
Net loss	34.2			83.6
Prior service cost	(6.1		)	(19.8		)
Total	$	242.2		$	261.1

The following amounts in the benefit obligations regulatory asset atDecember 31, 2015are expected to be recognized as components of net periodic benefit cost in2016: 

(In millions)
Pension Plan and Restoration of Retirement Income Plan
Net loss	$	13.1
Prior service cost	—
Postretirement Benefit Plans
Net loss	2.0
Prior service cost	6.1
Total	$	21.2

Income taxes recoverable from customers, which represents income tax benefits previously used to reduce OG&E's revenues, are treated as regulatory assets and liabilities and are being amortized over the estimated remaining life of the assets to which they relate.  These amounts are being recovered in rates as the temporary differences that generated the income tax benefit turn around.  The income tax related regulatory assets and liabilities are netted in income taxes recoverable from customers, net in the regulatory assets and liabilities table above.

OG&E defers annual Oklahoma storm-related operation and maintenance expenses in excess of$2.7 millionand includes in expense any Oklahoma storm-related operation and maintenance expenses up to$2.7 million. OG&E expects to recover the amounts deferred each year over afive-year period in accordance with historical practice.

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 expenses 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 not included in OG&E's rate base and does not otherwise earn a rate of return.

OG&E recovers a return on the capital expenditures along with operation and maintenance expense and depreciation expense related to the Crossroads wind farm through riders established by the OCC and APSC. OG&E began recovery in the fourth quarter of 2011 in Oklahoma and June of 2013 in Arkansas, and believes the rider will continue until new rates are implemented in OG&E's next general rate case in each jurisdiction.

OG&E recovers the cost of system-wide deployment of smart grid technology and implementing the smart grid pilot program, the incremental costs for web portal access, education and providing home energy reports. These amounts are currently being recovered through a rider which will remain in effect until the smart grid project costs are included in base rates in OG&E's next general rate case. Costs not included in the rider are the incremental costs for web portal access, education and home energy reports, which are capped at$6.9 million, and the stranded costs associated with OG&E's analog electric meters, which have been replaced by smart meters and were accumulated during the smart grid deployment and have been included in the Smart Grid asset in the regulatory assets and liabilities table above. These costs are expected to be recovered in base rates in OG&E's next general rate case.

Net accrued removal obligations represent asset retirement costs previously recovered from ratepayers for other than legal obligations.

OG&E recovers specific amounts of pension and postretirement medical costs in rates approved in its Oklahoma rate cases. 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 case as a regulatory asset or regulatory liability. These amounts have been recorded in the Pension tracker in the regulatory assets and liabilities table above.

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.IfOG&Ewere 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, which could have significant financial effects.

Use of Estimates

In preparing theConsolidatedFinancial 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 theConsolidatedFinancial Statements and the reported amounts of revenues and expenses during the reporting period.  Changes to these assumptions and estimates could have a material effect onthe Company's ConsolidatedFinancial Statements.  However,the Companybelieves it has taken reasonable positions where assumptions and estimates are used in order to minimize the negative financial impact tothe Companythat could result if actual results vary from the assumptions and estimates.  In management's opinion, the areas ofthe Companywhere the most significant judgment is exercisedfor all Company segmentsincludes the determination of Pension Plan assumptions,income taxes,contingency reserves, asset retirement obligationsand depreciable lives of property, plant and equipment. For the electric utility segment, significant judgment is also exercised inthe determination of regulatory assets and liabilities and unbilled revenues.

Cash and Cash Equivalents

For purposes of theConsolidatedFinancial Statements, the Company considers 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 calculated by multiplying the last six months of electric revenue by the provision rate.  The provision rate is based on a 12-month historical average of actual balances written off.  To the extent the historical collection rates are not representative of future collections, there could be an effect on the amount of uncollectible expense recognized.  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 on the Consolidated Balance Sheets and is included in the Other Operation and Maintenance Expense on the Consolidated Statements of Income. The allowance for uncollectible accounts receivable was$1.4 millionand$1.6 millionatDecember 31, 2015and2014, 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.

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$119.3 millionand$66.7 millionatDecember 31, 2015and2014, respectively. Effective May 1, 2014, the gas storage services agreement with Enable was terminated. As a result of this contract termination, approximately 5.3 Bcf of cushion gas owned by OG&E and stored on the Enable system is being directed to OG&E's power plants over a five year period during peak time of June 1 to August 31 at a rate of 11,500 MMBtu/day for a total of 1.06 Bcf per year. In 2014, approximately$11.0 millionof cushion gas was reclassified from Plant-in-Service to Other Deferred Assets and an additional$2.7 millionwas reclassified to current Fuel Inventories on the Balance Sheets. As of December 31, 2015, the balance of cushion gas in Other Deferred Assets is approximately$5.4 million.

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 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 Consolidated Statements of Income as Other Expense.  Repair and replacement of minor items of property are included in the Consolidated Statements of Income as Other Operation and Maintenance Expense.

The table below presents 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 Consolidated Statements of Income.

December 31, 2015 (In millions)	Percentage Ownership		Total Property, Plant and Equipment		Accumulated Depreciation		Net Property, Plant and Equipment
McClain Plant (A)	77	%	$	220.4	$	62.8	$	157.6
Redbud Plant (A)(B)	51	%	$	487.5	$	101.2	$	386.3

(A) Construction work in progress was$1.6 millionand$1.3 millionfor the McClain and Redbud Plants, respectively.

(B) This amount includes a plant acquisition adjustment of$148.3 millionand accumulated amortization of$39.8 million.

December 31, 2014 (In millions)	Percentage Ownership		Total Property, Plant and Equipment		Accumulated Depreciation		Net Property, Plant and Equipment
McClain Plant (A)	77	%	$	207.7	$	46.6	$	161.1
Redbud Plant (A)(B)	51	%	$	484.1	$	81.8	$	402.3

(A) Construction work in progress was$0.5 millionand$0.4 millionfor the McClain and Redbud Plants, respectively.

(B) This amount includes a plant acquisition adjustment of$148.3 millionand accumulated amortization of$34.3 million.

OGE Energy Consolidated

The Company's property, plant and equipment and related accumulated depreciation are divided into the following major classes at:

December 31, 2015 (In millions)	Total Property, Plant and Equipment		Accumulated Depreciation		Net Property, Plant and Equipment
OGE Energy (holding company)
Property, plant and equipment	$	139.0	$	112.7	$	26.3
OGE Energy property, plant and equipment	139.0		112.7		26.3
OG&E
Distribution assets	3,728.8		1,152.8		2,576.0
Electric generation assets (A)	3,837.4		1,407.0		2,430.4
Transmission assets (B)	2,454.2		440.7		2,013.5
Intangible plant	81.0		38.0		43.0
Other property and equipment	356.4		123.2		233.2
OG&E property, plant and equipment	10,457.8		3,161.7		7,296.1
Total property, plant and equipment	$	10,596.8	$	3,274.4	$	7,322.4

(A) This amount includes a plant acquisition adjustment of$148.3 millionand accumulated amortization of$39.8 million.

(B) This amount includes a plant acquisition adjustment of$3.3 millionand accumulated amortization of$0.5 million.

December 31, 2014 (In millions)	Total Property, Plant and Equipment		Accumulated Depreciation		Net Property, Plant and Equipment
OGE Energy (holding company)
Property, plant and equipment	$	151.7	$	113.3	$	38.4
OGE Energy property, plant and equipment	151.7		113.3		38.4
OG&E
Distribution assets	3,559.5		1,086.7		2,472.8
Electric generation assets (A)	3,620.1		1,345.1		2,275.0
Transmission assets (B)	2,370.0		417.8		1,952.2
Intangible plant	67.6		31.1		36.5
Other property and equipment	330.0		125.0		205.0
OG&E property, plant and equipment	9,947.2		3,005.7		6,941.5
Total property, plant and equipment	$	10,098.9	$	3,119.0	$	6,979.9

(A) This amount includes a plant acquisition adjustment of$148.3 millionand accumulated amortization of$34.3 million.

(B) This amount includes a plant acquisition adjustment of$3.3 millionand accumulated amortization of$0.4 million.

The following table summarizes the Company's unamortized computer software costs.

Year ended December 31 (In millions)	2015		2014
OGE Energy (holding company)	$	2.4	$	4.5
OG&E	34.3		33.6
Total	$	36.7	$	38.1

The following table summarizes the Company's amortization expense for computer software costs.

Year ended December 31 (In millions)	2015		2014		2013
OGE Energy (holding company)	$	2.0	$	4.3	$	6.4
OG&E	6.9		5.2		4.0
Enogex LLC	—		—		0.8
Total	$	8.9	$	9.5	$	11.2

Depreciation and Amortization

The provision for depreciation, which was2.9 percent and 2.8 percentof the average depreciable utility plant for 2015and2014, respectively, is provided on a 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. In2016, the provision for depreciation is projected to be2.9 percentof the average depreciable utility plant. Amortization of intangible assets is computed using the straight-line method. Of the remaining amortizable intangible plant balance atDecember 31, 2015, 96.4 percentwill be amortized overnineyears with the remaining3.6 percent of the intangible plant balance atDecember 31, 2015being amortized over26years.Amortization of plant acquisition adjustments is provided on a straight-line basis over the estimated remaining service life of the acquired asset.  Plant acquisition adjustments include$148.3 millionfor the Redbud Plant, which is being amortized over a27 yearlife and$3.3 millionfor certain transmission substation facilities in OG&E's service territory, which are being amortized over a37to59yearperiod.

Investment in Unconsolidated Affiliate

The Company'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, the Company 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. The Company 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 the Company's share of the investee's comprehensive income. The Company's maximum exposure to loss related to Enable is limited to the Company's equity investment in Enable as presented on the Company's Consolidated Balance Sheet at December 31, 2015. The Company 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.

The Company 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 which are classified as operating activities in the Consolidated Statements of Cash Flows. The Company considers distributions received from Enable in excess of cumulative equity in earnings subsequent to the date of investment to be a return of investment which are classified as investing activities in the Consolidated Statements of Cash Flows.

Asset Retirement Obligations

The Companyhas previously recorded asset retirement obligations that are being amortized over their respective lives ranging fromthreeto74years.

The following table summarizes changes to the Company's asset retirement obligations during theyears endedDecember 31, 2015and2014.

(In millions)	2015			2014
Balance at January 1	$	58.6		$	55.2
Accretion expense	2.6			2.5
Revisions in estimated cash flows (A)	1.6			1.7
Additions (B)	0.9			—
Liabilities settled (C)	(0.4		)	(0.8		)
Balance at December 31	$	63.3		$	58.6

(A) Assumptions changed related to the estimated cost of removal for one of OG&E's generating facilities.

(B) OG&E recorded an asset retirement obligation for$0.9 millionfor the ash pond located at the Muskogee generating facility.

(C) In 2015, asset retirement obligations were settled for the asbestos abatement at one of OG&E's generating facilities.

Allowance for Funds Used During Construction

Allowance for funds used during construction is calculated according to the FERC pronouncements for the imputed cost of equity and borrowed funds.  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 Consolidated Statements of Income and as an increase to Construction Work in Progress in the Consolidated Balance Sheets.Allowance for funds used during construction rates, compounded semi-annually, were8.1 percent, 6.9 percentand8.3 percentfor the years endedDecember 31, 2015, 2014and2013, respectively.Theincreasein the allowance for funds used during construction rates in 2015 was primarily due to short-term debt not being used to finance construction projects, which caused the equity portion of allowance for funds used during construction to increase.

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. OG&E reads its customers' meters 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 on theConsolidatedBalance Sheets and in Operating Revenues on theConsolidatedStatements 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.

The Company deconsolidated the results of operations for Enogex LLC as of May 1, 2013. Prior to this date, operating revenues for gathering, processing, transportation and storage services for Enogex LLC were recorded each month based on the current month's estimated volumes, contracted prices (considering current commodity prices), historical seasonal fluctuations and any known adjustments.  The estimates were reversed in the following month and customers were billed on actual volumes and contracted prices.  Gas sales were calculated on current-month nominations and contracted prices. Operating revenues associated with the production of NGLs were estimated based on current-month estimated production and contracted prices.  These amounts were reversed in the following month and the customers were billed on actual production and contracted prices.  

Enogex LLC recognized revenue from natural gas gathering, processing, transportation and storage services to third parties as services were provided.  Revenue associated with NGLs was recognized when the production was sold.  

Enogex LLC recorded deferred revenue when it received consideration from a third party before achieving certain criteria that must be met for revenue to be recognized in accordance with GAAP.

Enogex LLC engaged in asset management and hedging activities related to the purchase and sale of natural gas and NGLs. Contracts utilized in these activities generally included purchases and sales for physical delivery, over-the-counter forward swap and options contracts and exchange traded futures and options. 

SPP Purchases and Sales

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. On March 1, 2014, the SPP 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. These results are reported as Operating Revenues or Cost of Goods Sold in its Consolidated Financial Statements. 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.

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, the APSC and the FERC. The OCC, the APSC and the FERC have authority to review the appropriateness of gas transportation charges or other fees OG&E pays to its affiliate, Enable.

Income Taxes

The Companyfilesconsolidated income tax returns in the U.S. Federal jurisdiction and various state jurisdictions.  Income taxesaregenerally allocated to each company in the affiliated group based on its stand-alone taxable income or loss.Federal investment tax credits previously claimed on electric utility property have been deferred and are being amortized to income over the life of the related property.The Companyuses 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 Company recognizes interest related to unrecognized tax benefits in Interest Expense and recognizes penalties in Other Expense in the Consolidated Statements of Income.

Accrued Vacation

The Company accrues 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.

Accumulated Other Comprehensive Income (Loss)

The following tables summarize changes in the components of accumulated other comprehensive loss attributable to OGE Energy during 2014 and 2015. All amounts below are presented net of tax.

	Pension Plan and Restoration of Retirement Income Plan							Postretirement Benefit Plans
(In millions)	Net loss			Prior service cost		Settlement cost		Net loss			Prior service cost			Total
Balance at December 31, 2013	$	(27.4	)	$	0.1	$	—	$	(5.8	)	$	5.1		$	(28.0	)
Other comprehensive income (loss) before reclassifications	(11.1		)	—		—		(3.1		)	—			(14.2		)
Amounts reclassified from accumulated other comprehensive income (loss)	1.7			—		—		0.9			(1.8		)	0.8
Net current period other comprehensive income (loss)	(9.4		)	—		—		(2.2		)	(1.8		)	(13.4		)
Balance at December 31, 2014	$	(36.8	)	$	0.1	$	—	$	(8.0	)	$	3.3		$	(41.4	)
Other comprehensive income (loss) before reclassifications	(9.5		)	—		—		9.3			—			(0.2		)
Amounts reclassified from accumulated other comprehensive income (loss)	2.5			—		4.6		1.2			(1.8		)	6.5
Net current period other comprehensive income (loss)	(7.0		)	—		4.6		10.5			(1.8		)	6.3
Balance at December 31, 2015	$	(43.8	)	$	0.1	$	4.6	$	2.5		$	1.5		$	(35.1	)

The following table summarizes significant amounts reclassified out of accumulated other comprehensive loss by the respective line items in net income during the years ended December 31, 2015 and 2014.

Details about Accumulated Other Comprehensive Income (Loss) Components	Amount Reclassified from Accumulated Other Comprehensive Income (Loss)						Affected Line Item in the Statement Where Net Income is Presented
	Year Ended December 31,
(In millions)	2015			2014
Losses on cash flow hedges
Interest rate swap	$	—		$	(0.3	)	Interest expense
	—			(0.3		)	Total before tax
	—			(0.1		)	Tax benefit
	$	—		$	(0.2	)	Net of tax
Amortization of defined benefit pension and restoration of retirement income plan items
Actuarial losses	$	(4.7	)	$	(3.0	)	(A)
(Settlement) curtailment cost	(7.5		)	0.2			(A)
	(12.2		)	(2.8		)	Total before tax
	(5.1		)	(1.1		)	Tax benefit
	$	(7.1	)	$	(1.7	)	Net of tax
Amortization of postretirement benefit plan items
Actuarial losses	$	(2.0	)	$	(1.4	)	(A)
Prior service cost	2.9			2.9			(A)
	0.9			1.5			Total before tax
	0.3			0.6			Tax expense
	$	0.6		$	0.9		Net of tax
Total reclassifications for the period	$	(6.5	)	$	(1.0	)	Net of tax

(A) These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost (see Note 12 for additional information).

The amounts in accumulated other comprehensive loss atDecember 31, 2015that are expected to be recognized into earnings in2016are as follows:

(In millions)
Pension Plan and Restoration of Retirement Income Plan
Net loss	$	(4.8	)
Postretirement Benefit Plans
Net loss	—
Prior service cost	(2.6		)
Total, net of tax	$	(7.4	)

Environmental Costs

Accruals 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 expenseor 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 insuranceor raterecovery, 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 whereOG&E has been designated as one of several potentially responsible parties, the amount accrued representsOG&E'sestimated share of the cost.  The Company had$10.0 millionand$7.5 millioninaccrued environmental liabilities atDecember 31, 2015and2014, respectively, which are included in the asset retirement obligations table.