Retirement Plans and Postretirement Benefit Plans

3 Months Ended

Mar. 31, 2020

Defined Benefit Plan [Abstract]

Pension and Other Postretirement Benefits Disclosure [Text Block]

11.Retirement Plans and Postretirement Benefit Plans

Net Periodic Benefit Cost

The following table presents the net periodic benefit cost components, before consideration of capitalized amounts, of the Company's Pension Plan, Restoration of Retirement Income Plan and postretirement benefit plans that are included in the Condensed Consolidated Financial Statements. Service cost is presented within Other Operation and Maintenance, and the remaining net periodic benefit cost components as listed in the table below are presented within Other Net Periodic Benefit Expense in the Company's Condensed Consolidated 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 Expense in the Company's Condensed Consolidated Statements of Income.

	Pension Plan				Restoration of Retirement Income Plan				Postretirement Benefit Plans
	Three Months Ended				Three Months Ended				Three Months Ended
	March 31,				March 31,				March 31,
(In millions)	2020		2019		2020		2019		2020		2019
Service cost	$	3.7	$	3.5	$	0.2	$	0.1	$	0.1	$	0.1
Interest cost	4.6		5.7		0.1		0.1		1.1		1.4
Expected return on plan assets	(9.4)		(8.7)		—		—		(0.5)		(0.5)
Amortization of net loss	3.8		3.8		0.1		0.1		0.6		0.6
Amortization of unrecognized prior service cost (A)	—		—		—		—		(2.1)		(2.1)
Settlement cost	—		19.7		—		—		—		—
Total net periodic benefit cost	2.7		24.0		0.4		0.3		(0.8)		(0.5)
Less: Amount paid by unconsolidated affiliates	0.5		0.9		—		—		(0.2)		(0.2)
Net periodic benefit cost	$	2.2	$	23.1	$	0.4	$	0.3	$	(0.6)	$	(0.3)

(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 amounts recognized, as presented in the table above, for the Pension and Restoration of Retirement Income Plans for the three months ended March 31, 2020 and 2019, the Company recognized the following:

	Three Months Ended March 31,
(In millions)	2020		2019
Increase (decrease) of pension expense to maintain allowed recoverable amount in Oklahoma jurisdiction (A)	$	1.7	$	(1.0)
Deferral of pension expense related to pension settlement charges:
Oklahoma jurisdiction (A)	$	—	$	11.2
Arkansas jurisdiction (A)	$	—	$	1.0

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

In addition to the net periodic benefit income amounts recognized, as presented in the table above, for the postretirement benefit plans for the three months ended March 31, 2020 and 2019, the Company recognized the following:

	Three Months Ended March 31,
(In millions)	2020		2019
Increase of postretirement expense to maintain allowed recoverable amount in Oklahoma jurisdiction (A)	$	0.2	$	0.3

(A) Included in the Pension tracker, as presented in the regulatory assets and liabilities table in Note 1.

	Three Months Ended
	March 31,
(In millions)	2020		2019
Capitalized portion of net periodic pension benefit cost	$	1.0	$	1.0
Capitalized portion of net periodic postretirement benefit cost	$	—	$	0.1