Retirement Plans and Postretirement Benefit Plans

9 Months Ended

Sep. 30, 2018

Defined Benefit Plan [Abstract]

Pension and Other Postretirement Benefits Disclosure [Text Block]

Retirement Plans and Postretirement Benefit Plans

In accordance with ASC Topic 715, "Compensation - Retirement Benefits," a one-time settlement charge is required to be recorded by an organization when lump sum payments or other settlements that relieve the organization from the responsibility for the pension benefit obligation during the plan year exceed the service cost and interest cost components of the organization's net periodic pension cost. During the first nine months of 2018, the Company experienced an increase in both the number of employees electing to retire and the amount of lump sum payments paid to such employees upon retirement. As a result, the Company recorded pension settlement charges of$12.8 millionin the third quarter of 2018.The pension settlement charge did not require a cash outlay by the Company and did not increase the Company's total pension expense over time, as the charge was an acceleration of costs that otherwise would be recognized as pension expense in future periods.

Net Periodic Benefit Cost

The Company adopted ASU 2017-07 in the first quarter of 2018 and, as a result, presents the service cost component of net benefit cost in operating income and the other components of net benefit cost as non-operating within its Condensed Consolidated Statements of Income. Further, as required by ASU 2017-07, the Company adjusted prior year income statement presentation of the net benefit cost components, which were previously presented in total within Other Operation and Maintenance on the Company's Condensed Consolidated Statements of Income. The Company elected the practical expedient allowed by ASU 2017-07 to utilize amounts disclosed in the Company's retirement plans and postretirement benefit plans note for the prior comparative period as the estimation basis for applying the retrospective presentation requirements.

The following tables present 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 interest cost, expected return on plan assets, amortization of net loss, amortization of unrecognized prior service cost and settlement cost are presented within Other Net Periodic Benefit Income (Expense) on 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 Income (Expense) on the Company's Condensed Consolidated Statements of Income.

	Pension Plan												Restoration of Retirement Income Plan
	Three Months Ended						Nine Months Ended						Three Months Ended				Nine Months Ended
	September 30,						September 30,						September 30,				September 30,
(In millions)	2018 (B)			2017 (B)			2018 (C)			2017 (C)			2018 (B)		2017 (B)		2018 (C)		2017 (C)
Service cost	$	3.6		$	3.9		$	11.1		$	11.6		$	0.1	$	—	$	0.3	$	0.2
Interest cost	6.1			6.5			17.8			19.6			0.1		0.1		0.3		0.2
Expected return on plan assets	(10.7		)	(10.7		)	(33.0		)	(32.0		)	—		—		—		—
Amortization of net loss	3.9			4.4			12.2			13.1			0.1		0.1		0.5		0.3
Amortization of unrecognized prior service cost (A)	—			—			—			—			0.1		0.1		0.1		0.1
Settlement cost	12.2			—			12.2			—			0.6		—		0.6		—
Total net periodic benefit cost	15.1			4.1			20.3			12.3			1.0		0.3		1.8		0.8
Less: Amount paid by unconsolidated affiliates	0.7			1.2			1.9			2.9			0.1		—		0.1		—
Net periodic benefit cost	$	14.4		$	2.9		$	18.4		$	9.4		$	0.9	$	0.3	$	1.7	$	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.

(B) In addition to the$15.3 millionand$3.2 millionof net periodic benefit cost recognizedduring thethree months endedSeptember 30, 2018and2017, respectively, the Company recognized the following:

• a deferral of pension expense during the three months endedSeptember 30, 2018 of $10.5 millionrelated to the pension settlement charge of$12.8 millionin accordance with the Oklahoma Pension tracker regulatory liability (see Note 1);

• a deferral of pension expense during the three months endedSeptember 30, 2018 of $1.0 millionrelated to the Arkansas jurisdictional portion of the pension settlement charge of$12.8 million; and

• an increase in pension expense during thethree months endedSeptember 30, 2017of$2.7 millionto maintain the allowable amount to be recovered for pension expense in the Oklahoma jurisdiction, which is included in the Pension tracker regulatory liability (see Note 1).

(C) In addition to the $20.1 million and $10.2 million of net periodic benefit cost recognized during the nine months ended September 30, 2018 and 2017, respectively, the Company recognized the following:

• an increase in pension expense during the nine months endedSeptember 30, 2018 and 2017 of $7.8 million and $8.5 million, respectively, to maintain the allowable amount to be recovered for pension expense in the Oklahoma jurisdiction, which are included in the Pension tracker regulatory liability (see Note 1);

• a deferral of pension expense during the nine months endedSeptember 30, 2018 of $10.5 millionrelated to the pension settlement charge of$12.8 millionin accordance with the Oklahoma Pension tracker regulatory liability (see Note 1);

• a deferral of pension expense during the nine months endedSeptember 30, 2018 of $1.0 millionrelated to the Arkansas jurisdictional portion of the pension settlement charge of$12.8 million; and

• a deferral of pension expense during the nine months endedSeptember 30, 2017 of $2.3 million related to the Arkansas jurisdictional portion of the pension settlement charge of $22.4 million in 2013.

	Postretirement Benefit Plans
	Three Months Ended						Nine Months Ended
	September 30,						September 30,
(In millions)	2018 (B)			2017 (B)			2018 (C)			2017 (C)
Service cost	$	—		$	0.1		$	0.2		$	0.5
Interest cost	1.5			1.6			4.1			5.9
Expected return on plan assets	(0.5		)	(0.6		)	(1.5		)	(1.7		)
Amortization of net loss	1.0			0.5			2.9			1.3
Amortization of unrecognized prior service cost (A)	(2.1		)	(1.4		)	(6.3		)	(1.4		)
Settlement cost	—			0.6			—			0.6
Total net periodic benefit cost	(0.1		)	0.8			(0.6		)	5.2
Less: Amount paid by unconsolidated affiliates	(0.2		)	(0.1		)	(0.4		)	0.5
Net periodic benefit cost	$	0.1		$	0.9		$	(0.2	)	$	4.7

(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.

(B) In addition to the$0.1 million and $0.9 millionof net periodic benefit cost recognized during thethree months endedSeptember 30, 2018and2017, respectively, the Company recognizedan increase in postretirement medical expense in thethree months endedSeptember 30, 2018 and 2017 of $0.1 million and $1.9 million, respectively, to maintain the allowable amount to be recovered for postretirement medical expense in the Oklahoma jurisdiction which are included in the Pension tracker regulatory liability (see Note 1).

(C) In addition to the$0.2 millionof net periodic benefit income and$4.7 millionof net periodic benefit cost recognized during thenine months endedSeptember 30, 2018and2017, respectively, the Company recognizedan increase in postretirement medical expense in thenine months endedSeptember 30, 2018 and 2017 of $4.3 millionand$3.9 million, respectively, to maintain the allowable amount to be recovered for postretirement medical expense in the Oklahoma jurisdiction which are included in the Pension tracker regulatory liability (see Note 1).

As required by ASU 2017-07, the Company only capitalizes the service cost component of net benefit cost, beginning in the first quarter of 2018. Prior year capitalized amounts were not adjusted, as this change was implemented on a prospective basis.

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
(In millions)	2018		2017		2018		2017
Capitalized portion of net periodic pension benefit cost	$	0.9	$	1.0	$	2.8	$	3.3
Capitalized portion of net periodic postretirement benefit cost	$	—	$	0.1	$	0.1	$	1.3

Pension Plan Funding

In August 2018, the Company contributed $15.0 million to its Pension Plan. No additional contributions are expected in 2018.