Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

The items comprising income tax expense are as follows:

Year ended December 31 (In millions)	2015			2014			2013
Provision (Benefit) for Current Income Taxes
Federal	$	(17.5	)	$	(43.4	)	$	(3.2	)
State	(5.3		)	(6.3		)	0.6
Total Provision (Benefit) for Current Income Taxes	(22.8		)	(49.7		)	(2.6		)
Provision for Deferred Income Taxes, net
Federal	117.0			146.8			106.4
State	11.3			15.4			11.7
Total Provision for Deferred Income Taxes, net	128.3			162.2			118.1
Deferred Federal Investment Tax Credits, net	(0.7		)	(0.9		)	(2.0		)
Total Income Tax Expense	$	104.8		$	111.6		$	113.5

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

The following schedule reconciles the statutory tax rates to the effective income tax rate:

Year ended December 31	2015		2014		2013
Statutory Federal tax rate	35.0	%	35.0	%	35.0	%
Amortization of net unfunded deferred taxes	0.9		0.8		0.8
Federal investment tax credits, net	(0.2	)	(0.2	)	(0.5	)
State income taxes, net of Federal income tax benefit	0.5		0.8		—
Federal renewable energy credit (A)	(8.8	)	(9.4	)	(9.2	)
Uncertain tax positions	0.7		0.7		2.0
Other	(0.1	)	—		(0.2	)
Effective income tax rate	28.0	%	27.7	%	27.9	%

(A) Represents credits associated with the production from OG&E's wind farms.

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

December 31 (In millions)				2014
Current Deferred Income Tax Assets
Net operating losses				$	153.2
Accrued liabilities				6.0
Federal tax credits				8.3
Accrued vacation				2.7
Uncollectible accounts				0.6
Total Current Deferred Income Tax Assets				$	170.8
December 31 (In millions)	2015			2014
Non-Current Deferred Income Tax Liabilities, net
Accelerated depreciation and other property related differences	$	2,012.1		$	1,931.4
OG&E pension plan	55.1			77.2
Regulatory asset	32.7			24.7
Income taxes refundable to customers, net	22.0			21.7
Bond redemption-unamortized costs	4.8			5.3
Federal tax credits	(174.0		)	(137.4		)
State tax credits	(98.6		)	(91.6		)
Net operating losses	(89.7		)	(19.7		)
Regulatory liabilities	(46.3		)	(58.0		)
Postretirement medical and life insurance benefits	(40.8		)	(40.6		)
Asset retirement obligations	(22.5		)	(21.4		)
Other	(7.1		)	(4.6		)
Accrued liabilities	(5.9		)	—
Accrued vacation	(2.6		)	—
Deferred Federal investment tax credits	(0.9		)	(0.4		)
Uncollectible accounts	(0.5		)	—
Non-Current Deferred Income Tax Liabilities, net	$	1,637.8		$	1,686.6

Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]

Following is a reconciliation of the OG&E’s total gross unrecognized tax benefits as of the years ended December 31, 2015, 2014, and 2013.

(In millions)	2015		2014		2013
Balance at January 1	$	10.5	$	7.8	$	—
Tax positions related to current year:
Additions	2.7		2.7		2.7
Tax positions related to prior years:
Additions	—		—		5.1
Balance at December 31	$	13.2	$	10.5	$	7.8

Summary of Tax Credit Carryforwards [Table Text Block]

(In millions)	Carry Forward Amount		Deferred Tax Asset		Earliest Expiration Date
Net operating losses
State operating loss	$	562.6	$	20.7	2030
Federal operating loss	197.3		69.0		2030
Federal tax credits	174.0		174.0		2029
State tax credits
Oklahoma investment tax credits	115.6		75.1		N/A
Oklahoma capital investment board credits	7.3		7.3		N/A
Oklahoma zero emission tax credits	24.1		16.2		2020