Retirement Plans and Postretirement Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2025

Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]

Schedule of Defined Benefit Plans Disclosures [Table Text Block]

The following tables present the net periodic benefit cost components, before consideration of capitalized amounts, of OGE Energy's Pension Plan, Restoration of Retirement Income Plan and postretirement benefit plans that are included in the condensed financial statements. Service cost is presented within Other Operation and Maintenance Expense, and the remaining net periodic benefit cost components as listed in the following tables are presented within Other Net Periodic Benefit Income (Expense) in the

statements of income. 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 in the regulatory assets and liabilities table in Note 1 and within Other Net Periodic Benefit Income (Expense) in the statements of income.

	Pension Plan												Restoration of Retirement Income Plan
	Three Months Ended						Six Months Ended						Three Months Ended				Six Months Ended
OGE Energy	June 30,						June 30,						June 30,				June 30,
(In millions)	2025			2024			2025			2024			2025		2024		2025		2024
Service cost	$	1.3		$	1.3		$	2.7		$	2.7		$	0.2	$	0.3	$	0.5	$	0.5
Interest cost		4.1			4.0			8.1			7.8			0.1		0.1		0.2		0.2
Expected return on plan assets		(4.2	)		(4.5	)		(8.3	)		(8.2	)		—		—		—		—
Amortization of net loss		1.6			1.5			3.1			3.2			—		—		—		—
Amortization of unrecognized prior service cost (A)		—			—			—			—			0.2		—		0.2		0.1
Net periodic benefit cost	$	2.8		$	2.3		$	5.6		$	5.5		$	0.5	$	0.4	$	0.9	$	0.8

(A)Unamortized prior service cost is amortized on a straight-line basis over the average remaining service period to the first eligibility age of participants who are expected to receive a benefit and are active at the date of the plan amendment.

	Pension Plan												Restoration of Retirement Income Plan
	Three Months Ended						Six Months Ended						Three Months Ended				Six Months Ended
OG&E	June 30,						June 30,						June 30,				June 30,
(In millions)	2025			2024			2025			2024			2025		2024		2025		2024
Service cost	$	1.3		$	1.3		$	2.7		$	2.7		$	—	$	0.1	$	—	$	0.1
Interest cost		3.6			3.4			7.1			6.7			0.1		—		0.1		—
Expected return on plan assets		(3.6	)		(3.8	)		(7.1	)		(7.0	)		—		—		—		—
Amortization of net loss		1.5			1.5			2.9			3.1			—		—		—		—
Total net periodic benefit cost		2.8			2.4			5.6			5.5			0.1		0.1		0.1		0.1
Plus: Amount allocated from OGE Energy		—			—			—			—			0.4		0.3		0.8		0.7
Net periodic benefit cost	$	2.8		$	2.4		$	5.6		$	5.5		$	0.5	$	0.4	$	0.9	$	0.8

In addition to the net periodic benefit cost amounts recognized, as presented in the tables above, for the Pension and Restoration of Retirement Income Plans during the three and six months ended June 30, 2025 and 2024, the Registrants recognized the following:

	Three Months Ended					Six Months Ended
	June 30,					June 30,
(In millions)	2025			2024		2025			2024
Change in pension expense to maintain allowed recoverable amount in Oklahoma jurisdiction (A)	$	(0.2	)	$	2.6	$	(0.4	)	$	5.9

(A)Included in the pension regulatory asset in each jurisdiction, as indicated in the regulatory assets and liabilities table in Note 1.

	OGE Energy												OG&E
	Postretirement Benefit Plans												Postretirement Benefit Plans
	Three Months Ended						Six Months Ended						Three Months Ended						Six Months Ended
	June 30,						June 30,						June 30,						June 30,
(In millions)	2025			2024			2025			2024			2025			2024			2025			2024
Service cost	$	—		$	—		$	—		$	—		$	—		$	—		$	—		$	—
Interest cost		1.4			1.3			2.7			2.6			1.1			1.0			2.1			2.0
Expected return on plan assets		(0.4	)		(0.4	)		(0.8	)		(0.8	)		(0.3	)		(0.3	)		(0.7	)		(0.7	)
Amortization of net gain (loss)		0.2			—			0.2			(0.1	)		0.2			—			0.3			—
Total net periodic benefit cost		1.2			0.9			2.1			1.7			1.0			0.7			1.7			1.3
Plus: Amount allocated from OGE Energy														0.1			0.1			0.2			0.2
Net periodic benefit cost	$	1.2		$	0.9		$	2.1		$	1.7		$	1.1		$	0.8		$	1.9		$	1.5

In addition to the net periodic benefit cost amounts recognized, as presented in the table above, for the postretirement benefit plans during the three and six months ended June 30, 2025 and 2024, the Registrants recognized the following:

	Three Months Ended				Six Months Ended
	June 30,				June 30,
(In millions)	2025		2024		2025		2024
Change in postretirement expense to maintain allowed recoverable amount in Oklahoma jurisdiction (A)	$	0.3	$	1.1	$	0.3	$	2.2

(A)Included in the pension regulatory asset, as indicated in the regulatory assets and liabilities table in Note 1.

Schedule of Capitalized Pension and Postretirement Cost [Table Text Block]

The following table presents the amount of net periodic benefit cost capitalized and attributable to each of the Registrants for OGE Energy's Pension Plan and postretirement benefit plans for the three and six months ended June 30, 2025 and 2024.

	OGE Energy								OG&E
	Three Months Ended				Six Months Ended				Three Months Ended				Six Months Ended
	June 30,				June 30,				June 30,				June 30,
(In millions)	2025		2024		2025		2024		2025		2024		2025		2024
Capitalized portion of net periodic pension benefit cost	$	0.6	$	0.5	$	1.2	$	1.1	$	0.6	$	0.5	$	1.2	$	1.1
Capitalized portion of net periodic postretirement benefit cost	$	—	$	0.1	$	—	$	0.1	$	—	$	0.1	$	—	$	0.1