Retirement Plans and Postretirement Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2023

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						Three Months Ended
OGE Energy	March 31,						March 31,
(In millions)	2023			2022			2023		2022
Service cost	$	1.4		$	2.2		$	0.3	$	0.3
Interest cost		4.0			3.4			—		—
Expected return on plan assets		(4.0	)		(6.8	)		—		—
Amortization of net loss		2.2			1.9			—		—
Amortization of unrecognized prior service cost (A)		—			—			0.1		0.1
Settlement cost		18.2			13.2			—		—
Net periodic benefit cost	$	21.8		$	13.9		$	0.4	$	0.4

(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						Three Months Ended
OG&E	March 31,						March 31,
(In millions)	2023			2022			2023		2022
Service cost	$	1.1		$	1.7		$	—	$	—
Interest cost		3.1			2.6			—		—
Expected return on plan assets		(3.2	)		(5.3	)		—		—
Amortization of net loss		1.9			1.6			—		—
Settlement cost		17.2			3.6			—		—
Total net periodic benefit cost		20.1			4.2			—		—
Plus: Amount allocated from OGE Energy		1.6			1.8			0.4		0.4
Net periodic benefit cost	$	21.7		$	6.0		$	0.4	$	0.4

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 for the three months ended March 31, 2023 and 2022, the Registrants recognized the following:

	Three Months Ended March 31,
(In millions)	2023		2022
Increase of regulatory asset related to pension expense to maintain allowed recoverable amount in Oklahoma jurisdiction (A)	$	20.2	$	1.9
Deferral of pension expense related to pension settlement charges included in the above line item:
Oklahoma jurisdiction (A)	$	16.7	$	4.7
Arkansas jurisdiction (A)	$	1.5	$	0.4

(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						Three Months Ended
	March 31,						March 31,
(In millions)	2023			2022			2023			2022
Service cost	$	—		$	0.1		$	—		$	—
Interest cost		1.3			0.9			1.0			0.7
Expected return on plan assets		(0.4	)		(0.4	)		(0.4	)		(0.4	)
Amortization of net (gain) loss		(0.1	)		0.5			—			0.5
Amortization of unrecognized prior service cost (A)		—			(1.0	)		—			(0.9	)
Total net periodic benefit cost		0.8			0.1			0.6			(0.1	)
Plus: Amount allocated from OGE Energy								0.1			—
Net periodic benefit cost (income)	$	0.8		$	0.1		$	0.7		$	(0.1	)

(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.

In addition to the net periodic benefit cost or income amounts recognized, as presented in the table above, for the postretirement benefit plans for the three months ended March 31, 2023 and 2022, the Registrants recognized the following:

	Three Months Ended March 31,
(In millions)	2023		2022
Increase of regulatory asset and decrease of regulatory liability, respectively, related to postretirement expense to maintain allowed recoverable amount in Oklahoma jurisdiction (A)	$	1.1	$	(0.3	)

(A)Included in the pension regulatory asset or liability in each jurisdiction, as presented 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 months ended March 31, 2023 and 2022.

	OGE Energy				OG&E
	Three Months Ended				Three Months Ended
	March 31,				March 31,
(In millions)	2023		2022		2023		2022
Capitalized portion of net periodic pension benefit cost	$	0.6	$	0.8	$	0.5	$	0.7
Capitalized portion of net periodic postretirement benefit cost	$	—	$	0.1	$	—	$	—