Stock Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Stock-Based Compensation [Abstract]

Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block]

The following table presents the Registrants' pre-tax compensation expense and related income tax benefit for the years ended December 31, 2020, 2019 and 2018 related to performance units and restricted stock units for the Registrants' employees.

	OGE Energy						OG&E
Year Ended December 31 (In millions)	2020		2019		2018		2020		2019		2018
Performance units:
Total shareholder return	$	7.9	$	8.7	$	8.2	$	2.3	$	3.0	$	2.8
Earnings per share	1.0		4.3		5.1		0.3		1.5		1.8
Total performance units	8.9		13.0		13.3		2.6		4.5		4.6
Restricted stock units	0.9		0.9		0.1		0.4		0.4		—
Total compensation expense	$	9.8	$	13.9	$	13.4	$	3.0	$	4.9	$	4.6
Income tax benefit	$	2.5	$	3.6	$	3.4	$	0.8	$	1.3	$	1.2

Performance Units Total Shareholder Return Valuation Assumptions [Table Text Block]

The following table presents the number of performance units granted based on total shareholder return and the assumptions used to calculate the grant date fair value of the performance units based on total shareholder return.

	OGE Energy									OG&E
	2020			2019			2018			2020			2019			2018
Number of units granted	201,552			208,647			261,916			67,975			68,396			91,940
Fair value of units granted	$	38.03		$	47.00		$	36.86		$	38.03		$	47.00		$	36.86
Expected dividend yield	3.5		%	4.0		%	3.6		%	3.5		%	4.0		%	3.6		%
Expected price volatility	15.0		%	17.0		%	19.0		%	15.0		%	17.0		%	19.0		%
Risk-free interest rate	1.17		%	2.47		%	2.38		%	1.17		%	2.47		%	2.38		%
Expected life of units (in years)	2.85			2.86			2.86			2.85			2.86			2.86

Restricted Stock Valuation Assumptions [Table Text Block]

The following table presents the number of restricted stock units granted and the grant date fair value.

	OGE Energy						OG&E
	2020		2019		2018		2020		2019		2018
Restricted stock units granted	67,193		75,929		826		22,665		26,141		—
Fair value of restricted stock units granted	$	43.69	$	41.71	$	36.28	$	43.69	$	41.63	$	—

Share-based Compensation, Activity [Table Text Block]

The following tables present a summary of the activity for the Registrants' performance units and restricted stock units for the year ended December 31, 2020.

OGE Energy	Performance Units								Restricted Stock Units
	Total Shareholder Return				Earnings Per Share
(Dollars in millions)	Number of Units		Aggregate Intrinsic Value		Number of Units		Aggregate Intrinsic Value		Number of Shares	Aggregate Intrinsic Value
Units/shares outstanding at 12/31/19	664,817				155,171				72,880
Granted	201,552	(A)			—				67,193
Converted	(222,163)	(B)	$	11.5	(74,053)	(B)	$	6.6	N/A
Vested	N/A				N/A				(2,608)	$	(0.1)
Forfeited	(31,944)				(2,116)				(12,546)
Units/shares outstanding at 12/31/20	612,262		$	5.4	79,002		$	2.7	124,919	$	4.0
Units/shares fully vested at 12/31/20	236,990		$	5.4	79,002		$	2.7	1,752	$	0.1

OG&E	Performance Units								Restricted Stock Units
	Total Shareholder Return				Earnings Per Share
(Dollars in millions)	Number of Units		Aggregate Intrinsic Value		Number of Units		Aggregate Intrinsic Value		Number of Shares		Aggregate Intrinsic Value
Units/shares outstanding at 12/31/19	227,679				53,977				25,005
Granted	67,975	(A)			—				22,665
Converted	(77,799)	(B)	$	4.0	(25,931)	(B)	$	2.3	N/A
Vested	N/A				N/A				(1,113)		$	—
Forfeited	(28,985)				(1,969)				(11,100)
Employee migration	(6,507)	(C)			(842)	(C)			(1,327)	(C)
Units/shares outstanding at 12/31/20	182,363		$	1.7	25,235		$	0.8	34,130		$	1.1
Units/shares fully vested at 12/31/20	75,693		$	1.7	25,235		$	0.8	1,114		$	—

(A)For performance units, this represents the target number of performance units granted. Actual number of performance units earned, if any, is dependent upon performance and may range from zero percent to 200 percent of the target.

(B)These amounts represent performance units that vested at December 31, 2019 which were settled in March 2020.

(C)Due to certain employees transferring between OG&E and OGE Energy.

Schedule of Nonvested Share Activity [Table Text Block]

The following tables present a summary of the activity for the Registrants' non-vested performance units and restricted stock units for the year ended December 31, 2020.

OGE Energy	Performance Units							Restricted Stock Units
	Total Shareholder Return				Earnings Per Share
	Number of Units		Weighted-Average Grant Date Fair Value		Number of Units	Weighted-Average Grant Date Fair Value		Number of Shares	Weighted-Average Grant Date Fair Value
Units/shares non-vested at 12/31/19	442,654		$	41.43	81,118	$	31.03	72,880	$	41.66
Granted	201,552	(A)	$	38.03	—	$	—	67,193	$	43.69
Vested	(236,990)		$	36.86	(79,002)	$	31.03	(2,608)	$	40.30
Forfeited	(31,944)		$	41.15	(2,116)	$	31.03	(12,546)	$	42.60
Units/shares non-vested at 12/31/20	375,272		$	42.51	—	$	—	124,919	$	42.69

OG&E	Performance Units								Restricted Stock Units
	Total Shareholder Return				Earnings Per Share
	Number of Units		Weighted-Average Grant Date Fair Value		Number of Units		Weighted-Average Grant Date Fair Value		Number of Shares		Weighted-Average Grant Date Fair Value
Units/shares non-vested at 12/31/19	149,880		$	41.31	28,046		$	31.03	25,005		$	41.62
Granted	67,975	(A)	$	38.03	—		$	—	22,665		$	43.69
Vested	(75,693)		$	36.86	(25,235)		$	31.03	(1,113)		$	40.59
Forfeited	(28,985)		$	41.12	(1,969)		$	31.03	(11,100)		$	42.60
Employee migration	(6,507)	(B)	$	40.26	(842)	(B)	$	31.03	(1,327)	(B)	$	42.76
Units/shares non-vested at 12/31/20	106,670		$	42.49	—		$	—	34,130		$	42.67

(A)For performance units, this represents the target number of performance units granted. Actual number of performance units earned, if any, is dependent upon performance and may range from zero percent to 200 percent of the target.

(B)Due to certain employees transferring between OG&E and OGE Energy.

Fair Value of Vested Performance Units and Restricted Stock [Table Text Block]

The following table presents a summary of the Registrants' fair value for vested performance units and restricted stock units.

	OGE Energy						OG&E
Year Ended December 31 (In millions)	2020		2019		2018		2020		2019		2018
Performance units:
Total shareholder return	$	8.7	$	9.3	$	5.9	$	2.8	$	3.2	$	2.1
Earnings per share	$	2.5	$	5.2	$	4.9	$	0.8	$	0.9	$	1.7
Restricted stock units	$	0.1	$	0.1	$	0.1	$	0.1	$	—	$	—

Schedule of Unrecognized Compensation Cost, Nonvested Awards [Table Text Block]

The following table presents a summary of the Registrants' unrecognized compensation cost for non-vested performance units and restricted stock units and the weighted-average periods over which the compensation cost is expected to be recognized.

	OGE Energy			OG&E
December 31, 2020	Unrecognized Compensation Cost (In millions)		Weighted Average to be Recognized (In years)	Unrecognized Compensation Cost (In millions)		Weighted Average to be Recognized (In years)
Performance units - total shareholder return	$	7.1	1.62	$	1.8	1.64
Restricted stock units	1.6		1.65	0.4		1.68
Total unrecognized compensation cost	$	8.7		$	2.2