Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2014

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Regulatory Assets and Liabilities [Table Text Block]

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



December 31 (In millions)	2014		2013
Regulatory Assets
Current
Fuel clause under recoveries	$	68.3	$	26.2
Oklahoma demand program rider under recovery (A)	19.7		10.6
Crossroads wind farm rider under recovery (A)	—		4.7
Other (A)	9.1		7.3
Total Current Regulatory Assets	$	97.1	$	48.8
Non-Current
Benefit obligations regulatory asset	$	261.1	$	227.4
Income taxes recoverable from customers, net	56.1		56.5
Smart Grid	43.9		44.2
Deferred storm expenses	17.5		21.6
Unamortized loss on reacquired debt	16.1		11.8
Pension tracker	—		1.4
Other	16.8		16.2
Total Non-Current Regulatory Assets	$	411.5	$	379.1
Regulatory Liabilities
Current
Smart Grid rider over recovery (B)	$	12.5	$	16.7
Crossroads wind farm rider over recovery (B)	10.3		—
Other (B)	1.6		3.5
Total Current Regulatory Liabilities	$	24.4	$	20.2
Non-Current
Accrued removal obligations, net	$	248.1	$	227.7
Pension tracker	14.9		—
Deferred pension credits	—		6.5
Total Non-Current Regulatory Liabilities	$	263.0	$	234.2


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


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

Components of Benefit Obligation Regulatory Asset [Table Text Block]

The following table is a summary of the components of the benefit obligations regulatory asset at:



December 31 (In millions)	2014			2013
Pension Plan and Restoration of Retirement Income Plan
Net loss	$	196.7		$	178.4
Prior service cost	0.6			2.5
Postretirement Benefit Plans
Net loss	83.6			79.9
Prior service cost	(19.8		)	(33.4		)
Total	$	261.1		$	227.4

Schedule of Net Periodic Benefit Cost Not yet Recognized [Table Text Block]

The following amounts in the benefit obligations regulatory asset at December 31, 2014 are expected to be recognized as components of net periodic benefit cost in 2015:



(In millions)
Pension Plan and Restoration of Retirement Income Plan
Net loss	$	12.7
Prior service cost	0.5
Postretirement Benefit Plans
Net loss	11.8
Prior service cost	(13.7		)
Total	$	11.3

Schedule of Jointly Owned Utility Plants [Table Text Block]

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 Statement of Income.



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 million and $0.4 million for the McClain and Redbud Plants, respectively.


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



December 31, 2013 (In millions)	Percentage Ownership		Total Property, Plant and Equipment		Accumulated Depreciation		Net Property, Plant and Equipment
McClain Plant (A)	77	%	$	183.2	$	62.8	$	120.4
Redbud Plant (A)(B)	51	%	$	498.9	$	89.7	$	409.2


(A)	Construction work in progress was $0.1 million and $39.5 million for the McClain and Redbud Plants, respectively.


(B)	This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $28.8 million.

Property, Plant and Equipment [Table Text Block]

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



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 million and accumulated amortization of $34.3 million.


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



December 31, 2013 (In millions)	Total Property, Plant and Equipment		Accumulated Depreciation		Net Property, Plant and Equipment
OGE Energy (holding company)
Property, plant and equipment	$	152.4	$	114.2	$	38.2
OGE Energy property, plant and equipment	152.4		114.2		38.2
OG&E
Distribution assets	3,403.8		1,028.2		2,375.6
Electric generation assets (A)	3,551.0		1,306.1		2,244.9
Transmission assets (B)	2,163.7		385.0		1,778.7
Intangible plant	50.5		27.1		23.4
Other property and equipment	330.2		118.2		212.0
OG&E property, plant and equipment	9,499.2		2,864.6		6,634.6
Total property, plant and equipment	$	9,651.6	$	2,978.8	$	6,672.8


(A)	This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $28.8 million.


(B)	This amount includes a plant acquisition adjustment of $3.3 million and accumulated amortization of $0.3 million.

Schedule of Unamortized Computer Software Costs [Table Text Block]

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



December 31 (In millions)	2014		2013
OGE Energy (holding company)	$	4.5	$	7.2
OG&E	33.6		16.8
Total	$	38.1	$	24.0

Schedule of Computer Software Costs, Amortization [Table Text Block]

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



Year ended December 31 (In millions)	2014		2013		2012
OGE Energy (holding company)	$	4.3	$	6.4	$	6.8
OG&E	5.2		4.0		4.2
Enogex	—		0.8		3.1
Total	$	9.5	$	11.2	$	14.1

Schedule of Change in Asset Retirement Obligation [Table Text Block]

The following table summarizes changes to the Company's asset retirement obligations during the years ended December 31, 2014 and 2013.



(In millions)	2014			2013
Balance at January 1	$	55.2		$	54.0
Liabilities settled	(0.8		)	(0.4		)
Accretion expense	2.5			2.3
Revisions in estimated cash flows	1.7			(0.7		)
Balance at December 31	$	58.6		$	55.2

Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]

The following table summarizes changes in the components of accumulated other comprehensive loss attributable to OGE Energy during 2014. 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		Net loss			Prior service cost			Deferred interest rate swap hedging losses			Total
Balance at December 31, 2013	$	(27.4	)	$	0.1	$	(5.8	)	$	5.1		$	(0.2	)	$	(28.2	)
Other comprehensive income before reclassifications	(11.1		)	—		(3.1		)	—			—			(14.2		)
Amounts reclassified from accumulated other comprehensive income (loss)(A)	1.7			—		0.9			(1.8		)	0.2			1.0
Net current period other comprehensive income (loss)	(9.4		)	—		(2.2		)	(1.8		)	0.2			(13.2		)
Balance at December 31, 2014	$	(36.8	)	$	0.1	$	(8.0	)	$	3.3		$	—		$	(41.4	)

Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]

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



Details about Accumulated Other Comprehensive Loss Components	Amount Reclassified from Accumulated Other Comprehensive Loss						Affected Line Item in the Statement Where Net Income is Presented
	Year Ended December 31,
(In millions)	2014			2013
Losses on cash flow hedges
Commodity contracts	$	—		$	(1.0	)	Cost of sales
Interest rate swap	(0.3		)	(0.4		)	Interest expense
	(0.3		)	(1.4		)	Total before tax
	(0.1		)	(0.5		)	Tax benefit
	$	(0.2	)	$	(0.9	)	Net of tax

Amortization of defined benefit pension items
Actuarial losses	$	(3.0	)	$	(6.1	)	(A)
Settlement cost	0.2			(4.9		)	(A)
	(2.8		)	(11.0		)	Total before tax
	(1.1		)	(4.3		)	Tax benefit
	(1.7		)	(6.7		)	Net of tax
	—			(0.1		)	Noncontrolling interest
	$	(1.7	)	$	(6.6	)	Net of tax

Amortization of postretirement benefit plan items
Actuarial losses	$	(1.4	)	$	(3.3	)	(A)
Prior service cost	2.9			2.9			(A)
	1.5			(0.4		)	Total before tax
	0.6			(0.2		)	Tax benefit
	$	0.9		$	(0.2	)	Net of tax

Total reclassifications for the period	$	(1.0	)	$	(7.7	)	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).

Schedule of Amounts in Accumulated Other Comprehensive Income (Loss) to be Recognized over Next Fiscal Year [Table Text Block]

The amounts in accumulated other comprehensive loss at December 31, 2014 that are expected to be recognized into earnings in 2015 are as follows:



(In millions)
Pension Plan and Restoration of Retirement Income Plan
Net loss	$	(5.1	)
Postretirement Benefit Plans
Net loss	(1.9		)
Prior service cost	2.9
Total, net of tax	$	(4.1	)