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Benefit Plans
 9 Months Ended
Sep. 30, 2017
Benefit Plans
BENEFIT PLANS

The disclosures in this note apply to all Registrants except AEPTCo unless indicated otherwise.

AEP sponsors a qualified pension plan and two unfunded nonqualified pension plans.  Substantially all AEP employees are covered by the qualified plan or both the qualified and a nonqualified pension plan.  AEP also sponsors OPEB plans to provide health and life insurance benefits for retired employees.

Components of Net Periodic Benefit Cost

The following tables provide the components of net periodic benefit cost (credit) by Registrant for the plans:

AEP
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
24.1

 
$
21.4

 
$
2.8

 
$
2.6

Interest Cost
50.7

 
52.9

 
14.8

 
15.3

Expected Return on Plan Assets
(71.1
)
 
(70.1
)
 
(25.3
)
 
(26.8
)
Amortization of Prior Service Cost (Credit)
0.3

 
0.6

 
(17.3
)
 
(17.3
)
Amortization of Net Actuarial Loss
20.7

 
21.0

 
9.2

 
7.8

Net Periodic Benefit Cost (Credit)
$
24.7

 
$
25.8

 
$
(15.8
)
 
$
(18.4
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
72.3

 
$
64.3

 
$
8.4

 
$
7.7

Interest Cost
152.3

 
158.7

 
44.5

 
45.7

Expected Return on Plan Assets
(213.5
)
 
(210.2
)
 
(76.0
)
 
(80.3
)
Amortization of Prior Service Cost (Credit)
0.8

 
1.7

 
(51.8
)
 
(51.8
)
Amortization of Net Actuarial Loss
62.1

 
62.9

 
27.5

 
23.5

Net Periodic Benefit Cost (Credit)
$
74.0

 
$
77.4

 
$
(47.4
)
 
$
(55.2
)

APCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017

2016
 
2017
 
2016
 
(in millions)
Service Cost
$
2.3

 
$
2.1

 
$
0.3

 
$
0.2

Interest Cost
6.5

 
6.8

 
2.6

 
2.7

Expected Return on Plan Assets
(8.9
)
 
(8.8
)
 
(4.1
)
 
(4.3
)
Amortization of Prior Service Credit
—

 
—

 
(2.5
)
 
(2.5
)
Amortization of Net Actuarial Loss
2.6

 
2.6

 
1.6

 
1.4

Net Periodic Benefit Cost (Credit)
$
2.5

 
$
2.7

 
$
(2.1
)
 
$
(2.5
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
7.0

 
$
6.1

 
$
0.8

 
$
0.7

Interest Cost
19.3

 
20.4

 
7.9

 
8.1

Expected Return on Plan Assets
(26.8
)
 
(26.5
)
 
(12.3
)
 
(13.0
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(7.5
)
 
(7.5
)
Amortization of Net Actuarial Loss
7.8

 
8.0

 
4.7

 
4.1

Net Periodic Benefit Cost (Credit)
$
7.4

 
$
8.1

 
$
(6.4
)
 
$
(7.6
)


I&M
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
3.5

 
$
3.1

 
$
0.4

 
$
0.4

Interest Cost
6.1

 
6.3

 
1.7

 
1.7

Expected Return on Plan Assets
(8.6
)
 
(8.4
)
 
(3.1
)
 
(3.2
)
Amortization of Prior Service Credit
—

 
—

 
(2.3
)
 
(2.4
)
Amortization of Net Actuarial Loss
2.4

 
2.5

 
1.1

 
0.9

Net Periodic Benefit Cost (Credit)
$
3.4

 
$
3.5

 
$
(2.2
)
 
$
(2.6
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
10.5

 
$
9.2

 
$
1.2

 
$
1.1

Interest Cost
18.2

 
19.0

 
5.2

 
5.2

Expected Return on Plan Assets
(25.9
)
 
(25.2
)
 
(9.2
)
 
(9.6
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(7.0
)
 
(7.1
)
Amortization of Net Actuarial Loss
7.3

 
7.4

 
3.3

 
2.8

Net Periodic Benefit Cost (Credit)
$
10.2

 
$
10.5

 
$
(6.5
)
 
$
(7.6
)

OPCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
1.8

 
$
1.6

 
$
0.3

 
$
0.2

Interest Cost
4.8

 
5.1

 
1.6

 
1.8

Expected Return on Plan Assets
(6.9
)
 
(6.9
)
 
(3.0
)
 
(3.3
)
Amortization of Prior Service Credit
—

 
—

 
(1.7
)
 
(1.7
)
Amortization of Net Actuarial Loss
2.0

 
2.1

 
1.1

 
0.9

Net Periodic Benefit Cost (Credit)
$
1.7

 
$
1.9

 
$
(1.7
)
 
$
(2.1
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
5.6

 
$
4.9

 
$
0.7

 
$
0.6

Interest Cost
14.5

 
15.4

 
5.0

 
5.3

Expected Return on Plan Assets
(20.9
)
 
(20.8
)
 
(9.0
)
 
(9.7
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(5.2
)
 
(5.2
)
Amortization of Net Actuarial Loss
5.9

 
6.1

 
3.3

 
2.8

Net Periodic Benefit Cost (Credit)
$
5.2

 
$
5.7

 
$
(5.2
)
 
$
(6.2
)


PSO
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
1.7

 
$
1.5

 
$
0.2

 
$
0.2

Interest Cost
2.6

 
2.8

 
0.8

 
0.8

Expected Return on Plan Assets
(3.9
)
 
(3.9
)
 
(1.4
)
 
(1.5
)
Amortization of Prior Service Cost (Credit)
—

 
0.1

 
(1.1
)
 
(1.1
)
Amortization of Net Actuarial Loss
1.1

 
1.1

 
0.5

 
0.4

Net Periodic Benefit Cost (Credit)
$
1.5

 
$
1.6

 
$
(1.0
)
 
$
(1.2
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
4.9

 
$
4.6

 
$
0.5

 
$
0.5

Interest Cost
8.0

 
8.4

 
2.4

 
2.4

Expected Return on Plan Assets
(11.8
)
 
(11.6
)
 
(4.2
)
 
(4.5
)
Amortization of Prior Service Cost (Credit)
—

 
0.2

 
(3.2
)
 
(3.2
)
Amortization of Net Actuarial Loss
3.3

 
3.3

 
1.5

 
1.3

Net Periodic Benefit Cost (Credit)
$
4.4

 
$
4.9

 
$
(3.0
)
 
$
(3.5
)


SWEPCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
2.1

 
$
2.0

 
$
0.2

 
$
0.2

Interest Cost
3.1

 
3.1

 
0.9

 
0.9

Expected Return on Plan Assets
(4.2
)
 
(4.0
)
 
(1.5
)
 
(1.7
)
Amortization of Prior Service Credit
—

 
—

 
(1.3
)
 
(1.3
)
Amortization of Net Actuarial Loss
1.3

 
1.2

 
0.5

 
0.5

Net Periodic Benefit Cost (Credit)
$
2.3

 
$
2.3

 
$
(1.2
)
 
$
(1.4
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
6.5

 
$
6.1

 
$
0.6

 
$
0.6

Interest Cost
9.2

 
9.3

 
2.7

 
2.7

Expected Return on Plan Assets
(12.6
)
 
(12.3
)
 
(4.7
)
 
(5.0
)
Amortization of Prior Service Cost (Credit)
—

 
0.2

 
(3.9
)
 
(3.9
)
Amortization of Net Actuarial Loss
3.7

 
3.6

 
1.7

 
1.5

Net Periodic Benefit Cost (Credit)
$
6.8

 
$
6.9

 
$
(3.6
)
 
$
(4.1
)
Appalachian Power Co [Member]  
Benefit Plans
BENEFIT PLANS

The disclosures in this note apply to all Registrants except AEPTCo unless indicated otherwise.

AEP sponsors a qualified pension plan and two unfunded nonqualified pension plans.  Substantially all AEP employees are covered by the qualified plan or both the qualified and a nonqualified pension plan.  AEP also sponsors OPEB plans to provide health and life insurance benefits for retired employees.

Components of Net Periodic Benefit Cost

The following tables provide the components of net periodic benefit cost (credit) by Registrant for the plans:

AEP
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
24.1

 
$
21.4

 
$
2.8

 
$
2.6

Interest Cost
50.7

 
52.9

 
14.8

 
15.3

Expected Return on Plan Assets
(71.1
)
 
(70.1
)
 
(25.3
)
 
(26.8
)
Amortization of Prior Service Cost (Credit)
0.3

 
0.6

 
(17.3
)
 
(17.3
)
Amortization of Net Actuarial Loss
20.7

 
21.0

 
9.2

 
7.8

Net Periodic Benefit Cost (Credit)
$
24.7

 
$
25.8

 
$
(15.8
)
 
$
(18.4
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
72.3

 
$
64.3

 
$
8.4

 
$
7.7

Interest Cost
152.3

 
158.7

 
44.5

 
45.7

Expected Return on Plan Assets
(213.5
)
 
(210.2
)
 
(76.0
)
 
(80.3
)
Amortization of Prior Service Cost (Credit)
0.8

 
1.7

 
(51.8
)
 
(51.8
)
Amortization of Net Actuarial Loss
62.1

 
62.9

 
27.5

 
23.5

Net Periodic Benefit Cost (Credit)
$
74.0

 
$
77.4

 
$
(47.4
)
 
$
(55.2
)

APCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017

2016
 
2017
 
2016
 
(in millions)
Service Cost
$
2.3

 
$
2.1

 
$
0.3

 
$
0.2

Interest Cost
6.5

 
6.8

 
2.6

 
2.7

Expected Return on Plan Assets
(8.9
)
 
(8.8
)
 
(4.1
)
 
(4.3
)
Amortization of Prior Service Credit
—

 
—

 
(2.5
)
 
(2.5
)
Amortization of Net Actuarial Loss
2.6

 
2.6

 
1.6

 
1.4

Net Periodic Benefit Cost (Credit)
$
2.5

 
$
2.7

 
$
(2.1
)
 
$
(2.5
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
7.0

 
$
6.1

 
$
0.8

 
$
0.7

Interest Cost
19.3

 
20.4

 
7.9

 
8.1

Expected Return on Plan Assets
(26.8
)
 
(26.5
)
 
(12.3
)
 
(13.0
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(7.5
)
 
(7.5
)
Amortization of Net Actuarial Loss
7.8

 
8.0

 
4.7

 
4.1

Net Periodic Benefit Cost (Credit)
$
7.4

 
$
8.1

 
$
(6.4
)
 
$
(7.6
)


I&M
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
3.5

 
$
3.1

 
$
0.4

 
$
0.4

Interest Cost
6.1

 
6.3

 
1.7

 
1.7

Expected Return on Plan Assets
(8.6
)
 
(8.4
)
 
(3.1
)
 
(3.2
)
Amortization of Prior Service Credit
—

 
—

 
(2.3
)
 
(2.4
)
Amortization of Net Actuarial Loss
2.4

 
2.5

 
1.1

 
0.9

Net Periodic Benefit Cost (Credit)
$
3.4

 
$
3.5

 
$
(2.2
)
 
$
(2.6
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
10.5

 
$
9.2

 
$
1.2

 
$
1.1

Interest Cost
18.2

 
19.0

 
5.2

 
5.2

Expected Return on Plan Assets
(25.9
)
 
(25.2
)
 
(9.2
)
 
(9.6
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(7.0
)
 
(7.1
)
Amortization of Net Actuarial Loss
7.3

 
7.4

 
3.3

 
2.8

Net Periodic Benefit Cost (Credit)
$
10.2

 
$
10.5

 
$
(6.5
)
 
$
(7.6
)

OPCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
1.8

 
$
1.6

 
$
0.3

 
$
0.2

Interest Cost
4.8

 
5.1

 
1.6

 
1.8

Expected Return on Plan Assets
(6.9
)
 
(6.9
)
 
(3.0
)
 
(3.3
)
Amortization of Prior Service Credit
—

 
—

 
(1.7
)
 
(1.7
)
Amortization of Net Actuarial Loss
2.0

 
2.1

 
1.1

 
0.9

Net Periodic Benefit Cost (Credit)
$
1.7

 
$
1.9

 
$
(1.7
)
 
$
(2.1
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
5.6

 
$
4.9

 
$
0.7

 
$
0.6

Interest Cost
14.5

 
15.4

 
5.0

 
5.3

Expected Return on Plan Assets
(20.9
)
 
(20.8
)
 
(9.0
)
 
(9.7
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(5.2
)
 
(5.2
)
Amortization of Net Actuarial Loss
5.9

 
6.1

 
3.3

 
2.8

Net Periodic Benefit Cost (Credit)
$
5.2

 
$
5.7

 
$
(5.2
)
 
$
(6.2
)


PSO
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
1.7

 
$
1.5

 
$
0.2

 
$
0.2

Interest Cost
2.6

 
2.8

 
0.8

 
0.8

Expected Return on Plan Assets
(3.9
)
 
(3.9
)
 
(1.4
)
 
(1.5
)
Amortization of Prior Service Cost (Credit)
—

 
0.1

 
(1.1
)
 
(1.1
)
Amortization of Net Actuarial Loss
1.1

 
1.1

 
0.5

 
0.4

Net Periodic Benefit Cost (Credit)
$
1.5

 
$
1.6

 
$
(1.0
)
 
$
(1.2
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
4.9

 
$
4.6

 
$
0.5

 
$
0.5

Interest Cost
8.0

 
8.4

 
2.4

 
2.4

Expected Return on Plan Assets
(11.8
)
 
(11.6
)
 
(4.2
)
 
(4.5
)
Amortization of Prior Service Cost (Credit)
—

 
0.2

 
(3.2
)
 
(3.2
)
Amortization of Net Actuarial Loss
3.3

 
3.3

 
1.5

 
1.3

Net Periodic Benefit Cost (Credit)
$
4.4

 
$
4.9

 
$
(3.0
)
 
$
(3.5
)


SWEPCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
2.1

 
$
2.0

 
$
0.2

 
$
0.2

Interest Cost
3.1

 
3.1

 
0.9

 
0.9

Expected Return on Plan Assets
(4.2
)
 
(4.0
)
 
(1.5
)
 
(1.7
)
Amortization of Prior Service Credit
—

 
—

 
(1.3
)
 
(1.3
)
Amortization of Net Actuarial Loss
1.3

 
1.2

 
0.5

 
0.5

Net Periodic Benefit Cost (Credit)
$
2.3

 
$
2.3

 
$
(1.2
)
 
$
(1.4
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
6.5

 
$
6.1

 
$
0.6

 
$
0.6

Interest Cost
9.2

 
9.3

 
2.7

 
2.7

Expected Return on Plan Assets
(12.6
)
 
(12.3
)
 
(4.7
)
 
(5.0
)
Amortization of Prior Service Cost (Credit)
—

 
0.2

 
(3.9
)
 
(3.9
)
Amortization of Net Actuarial Loss
3.7

 
3.6

 
1.7

 
1.5

Net Periodic Benefit Cost (Credit)
$
6.8

 
$
6.9

 
$
(3.6
)
 
$
(4.1
)
Indiana Michigan Power Co [Member]  
Benefit Plans
BENEFIT PLANS

The disclosures in this note apply to all Registrants except AEPTCo unless indicated otherwise.

AEP sponsors a qualified pension plan and two unfunded nonqualified pension plans.  Substantially all AEP employees are covered by the qualified plan or both the qualified and a nonqualified pension plan.  AEP also sponsors OPEB plans to provide health and life insurance benefits for retired employees.

Components of Net Periodic Benefit Cost

The following tables provide the components of net periodic benefit cost (credit) by Registrant for the plans:

AEP
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
24.1

 
$
21.4

 
$
2.8

 
$
2.6

Interest Cost
50.7

 
52.9

 
14.8

 
15.3

Expected Return on Plan Assets
(71.1
)
 
(70.1
)
 
(25.3
)
 
(26.8
)
Amortization of Prior Service Cost (Credit)
0.3

 
0.6

 
(17.3
)
 
(17.3
)
Amortization of Net Actuarial Loss
20.7

 
21.0

 
9.2

 
7.8

Net Periodic Benefit Cost (Credit)
$
24.7

 
$
25.8

 
$
(15.8
)
 
$
(18.4
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
72.3

 
$
64.3

 
$
8.4

 
$
7.7

Interest Cost
152.3

 
158.7

 
44.5

 
45.7

Expected Return on Plan Assets
(213.5
)
 
(210.2
)
 
(76.0
)
 
(80.3
)
Amortization of Prior Service Cost (Credit)
0.8

 
1.7

 
(51.8
)
 
(51.8
)
Amortization of Net Actuarial Loss
62.1

 
62.9

 
27.5

 
23.5

Net Periodic Benefit Cost (Credit)
$
74.0

 
$
77.4

 
$
(47.4
)
 
$
(55.2
)

APCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017

2016
 
2017
 
2016
 
(in millions)
Service Cost
$
2.3

 
$
2.1

 
$
0.3

 
$
0.2

Interest Cost
6.5

 
6.8

 
2.6

 
2.7

Expected Return on Plan Assets
(8.9
)
 
(8.8
)
 
(4.1
)
 
(4.3
)
Amortization of Prior Service Credit
—

 
—

 
(2.5
)
 
(2.5
)
Amortization of Net Actuarial Loss
2.6

 
2.6

 
1.6

 
1.4

Net Periodic Benefit Cost (Credit)
$
2.5

 
$
2.7

 
$
(2.1
)
 
$
(2.5
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
7.0

 
$
6.1

 
$
0.8

 
$
0.7

Interest Cost
19.3

 
20.4

 
7.9

 
8.1

Expected Return on Plan Assets
(26.8
)
 
(26.5
)
 
(12.3
)
 
(13.0
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(7.5
)
 
(7.5
)
Amortization of Net Actuarial Loss
7.8

 
8.0

 
4.7

 
4.1

Net Periodic Benefit Cost (Credit)
$
7.4

 
$
8.1

 
$
(6.4
)
 
$
(7.6
)


I&M
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
3.5

 
$
3.1

 
$
0.4

 
$
0.4

Interest Cost
6.1

 
6.3

 
1.7

 
1.7

Expected Return on Plan Assets
(8.6
)
 
(8.4
)
 
(3.1
)
 
(3.2
)
Amortization of Prior Service Credit
—

 
—

 
(2.3
)
 
(2.4
)
Amortization of Net Actuarial Loss
2.4

 
2.5

 
1.1

 
0.9

Net Periodic Benefit Cost (Credit)
$
3.4

 
$
3.5

 
$
(2.2
)
 
$
(2.6
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
10.5

 
$
9.2

 
$
1.2

 
$
1.1

Interest Cost
18.2

 
19.0

 
5.2

 
5.2

Expected Return on Plan Assets
(25.9
)
 
(25.2
)
 
(9.2
)
 
(9.6
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(7.0
)
 
(7.1
)
Amortization of Net Actuarial Loss
7.3

 
7.4

 
3.3

 
2.8

Net Periodic Benefit Cost (Credit)
$
10.2

 
$
10.5

 
$
(6.5
)
 
$
(7.6
)

OPCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
1.8

 
$
1.6

 
$
0.3

 
$
0.2

Interest Cost
4.8

 
5.1

 
1.6

 
1.8

Expected Return on Plan Assets
(6.9
)
 
(6.9
)
 
(3.0
)
 
(3.3
)
Amortization of Prior Service Credit
—

 
—

 
(1.7
)
 
(1.7
)
Amortization of Net Actuarial Loss
2.0

 
2.1

 
1.1

 
0.9

Net Periodic Benefit Cost (Credit)
$
1.7

 
$
1.9

 
$
(1.7
)
 
$
(2.1
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
5.6

 
$
4.9

 
$
0.7

 
$
0.6

Interest Cost
14.5

 
15.4

 
5.0

 
5.3

Expected Return on Plan Assets
(20.9
)
 
(20.8
)
 
(9.0
)
 
(9.7
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(5.2
)
 
(5.2
)
Amortization of Net Actuarial Loss
5.9

 
6.1

 
3.3

 
2.8

Net Periodic Benefit Cost (Credit)
$
5.2

 
$
5.7

 
$
(5.2
)
 
$
(6.2
)


PSO
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
1.7

 
$
1.5

 
$
0.2

 
$
0.2

Interest Cost
2.6

 
2.8

 
0.8

 
0.8

Expected Return on Plan Assets
(3.9
)
 
(3.9
)
 
(1.4
)
 
(1.5
)
Amortization of Prior Service Cost (Credit)
—

 
0.1

 
(1.1
)
 
(1.1
)
Amortization of Net Actuarial Loss
1.1

 
1.1

 
0.5

 
0.4

Net Periodic Benefit Cost (Credit)
$
1.5

 
$
1.6

 
$
(1.0
)
 
$
(1.2
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
4.9

 
$
4.6

 
$
0.5

 
$
0.5

Interest Cost
8.0

 
8.4

 
2.4

 
2.4

Expected Return on Plan Assets
(11.8
)
 
(11.6
)
 
(4.2
)
 
(4.5
)
Amortization of Prior Service Cost (Credit)
—

 
0.2

 
(3.2
)
 
(3.2
)
Amortization of Net Actuarial Loss
3.3

 
3.3

 
1.5

 
1.3

Net Periodic Benefit Cost (Credit)
$
4.4

 
$
4.9

 
$
(3.0
)
 
$
(3.5
)


SWEPCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
2.1

 
$
2.0

 
$
0.2

 
$
0.2

Interest Cost
3.1

 
3.1

 
0.9

 
0.9

Expected Return on Plan Assets
(4.2
)
 
(4.0
)
 
(1.5
)
 
(1.7
)
Amortization of Prior Service Credit
—

 
—

 
(1.3
)
 
(1.3
)
Amortization of Net Actuarial Loss
1.3

 
1.2

 
0.5

 
0.5

Net Periodic Benefit Cost (Credit)
$
2.3

 
$
2.3

 
$
(1.2
)
 
$
(1.4
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
6.5

 
$
6.1

 
$
0.6

 
$
0.6

Interest Cost
9.2

 
9.3

 
2.7

 
2.7

Expected Return on Plan Assets
(12.6
)
 
(12.3
)
 
(4.7
)
 
(5.0
)
Amortization of Prior Service Cost (Credit)
—

 
0.2

 
(3.9
)
 
(3.9
)
Amortization of Net Actuarial Loss
3.7

 
3.6

 
1.7

 
1.5

Net Periodic Benefit Cost (Credit)
$
6.8

 
$
6.9

 
$
(3.6
)
 
$
(4.1
)
Ohio Power Co [Member]  
Benefit Plans
BENEFIT PLANS

The disclosures in this note apply to all Registrants except AEPTCo unless indicated otherwise.

AEP sponsors a qualified pension plan and two unfunded nonqualified pension plans.  Substantially all AEP employees are covered by the qualified plan or both the qualified and a nonqualified pension plan.  AEP also sponsors OPEB plans to provide health and life insurance benefits for retired employees.

Components of Net Periodic Benefit Cost

The following tables provide the components of net periodic benefit cost (credit) by Registrant for the plans:

AEP
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
24.1

 
$
21.4

 
$
2.8

 
$
2.6

Interest Cost
50.7

 
52.9

 
14.8

 
15.3

Expected Return on Plan Assets
(71.1
)
 
(70.1
)
 
(25.3
)
 
(26.8
)
Amortization of Prior Service Cost (Credit)
0.3

 
0.6

 
(17.3
)
 
(17.3
)
Amortization of Net Actuarial Loss
20.7

 
21.0

 
9.2

 
7.8

Net Periodic Benefit Cost (Credit)
$
24.7

 
$
25.8

 
$
(15.8
)
 
$
(18.4
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
72.3

 
$
64.3

 
$
8.4

 
$
7.7

Interest Cost
152.3

 
158.7

 
44.5

 
45.7

Expected Return on Plan Assets
(213.5
)
 
(210.2
)
 
(76.0
)
 
(80.3
)
Amortization of Prior Service Cost (Credit)
0.8

 
1.7

 
(51.8
)
 
(51.8
)
Amortization of Net Actuarial Loss
62.1

 
62.9

 
27.5

 
23.5

Net Periodic Benefit Cost (Credit)
$
74.0

 
$
77.4

 
$
(47.4
)
 
$
(55.2
)

APCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017

2016
 
2017
 
2016
 
(in millions)
Service Cost
$
2.3

 
$
2.1

 
$
0.3

 
$
0.2

Interest Cost
6.5

 
6.8

 
2.6

 
2.7

Expected Return on Plan Assets
(8.9
)
 
(8.8
)
 
(4.1
)
 
(4.3
)
Amortization of Prior Service Credit
—

 
—

 
(2.5
)
 
(2.5
)
Amortization of Net Actuarial Loss
2.6

 
2.6

 
1.6

 
1.4

Net Periodic Benefit Cost (Credit)
$
2.5

 
$
2.7

 
$
(2.1
)
 
$
(2.5
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
7.0

 
$
6.1

 
$
0.8

 
$
0.7

Interest Cost
19.3

 
20.4

 
7.9

 
8.1

Expected Return on Plan Assets
(26.8
)
 
(26.5
)
 
(12.3
)
 
(13.0
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(7.5
)
 
(7.5
)
Amortization of Net Actuarial Loss
7.8

 
8.0

 
4.7

 
4.1

Net Periodic Benefit Cost (Credit)
$
7.4

 
$
8.1

 
$
(6.4
)
 
$
(7.6
)


I&M
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
3.5

 
$
3.1

 
$
0.4

 
$
0.4

Interest Cost
6.1

 
6.3

 
1.7

 
1.7

Expected Return on Plan Assets
(8.6
)
 
(8.4
)
 
(3.1
)
 
(3.2
)
Amortization of Prior Service Credit
—

 
—

 
(2.3
)
 
(2.4
)
Amortization of Net Actuarial Loss
2.4

 
2.5

 
1.1

 
0.9

Net Periodic Benefit Cost (Credit)
$
3.4

 
$
3.5

 
$
(2.2
)
 
$
(2.6
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
10.5

 
$
9.2

 
$
1.2

 
$
1.1

Interest Cost
18.2

 
19.0

 
5.2

 
5.2

Expected Return on Plan Assets
(25.9
)
 
(25.2
)
 
(9.2
)
 
(9.6
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(7.0
)
 
(7.1
)
Amortization of Net Actuarial Loss
7.3

 
7.4

 
3.3

 
2.8

Net Periodic Benefit Cost (Credit)
$
10.2

 
$
10.5

 
$
(6.5
)
 
$
(7.6
)

OPCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
1.8

 
$
1.6

 
$
0.3

 
$
0.2

Interest Cost
4.8

 
5.1

 
1.6

 
1.8

Expected Return on Plan Assets
(6.9
)
 
(6.9
)
 
(3.0
)
 
(3.3
)
Amortization of Prior Service Credit
—

 
—

 
(1.7
)
 
(1.7
)
Amortization of Net Actuarial Loss
2.0

 
2.1

 
1.1

 
0.9

Net Periodic Benefit Cost (Credit)
$
1.7

 
$
1.9

 
$
(1.7
)
 
$
(2.1
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
5.6

 
$
4.9

 
$
0.7

 
$
0.6

Interest Cost
14.5

 
15.4

 
5.0

 
5.3

Expected Return on Plan Assets
(20.9
)
 
(20.8
)
 
(9.0
)
 
(9.7
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(5.2
)
 
(5.2
)
Amortization of Net Actuarial Loss
5.9

 
6.1

 
3.3

 
2.8

Net Periodic Benefit Cost (Credit)
$
5.2

 
$
5.7

 
$
(5.2
)
 
$
(6.2
)


PSO
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
1.7

 
$
1.5

 
$
0.2

 
$
0.2

Interest Cost
2.6

 
2.8

 
0.8

 
0.8

Expected Return on Plan Assets
(3.9
)
 
(3.9
)
 
(1.4
)
 
(1.5
)
Amortization of Prior Service Cost (Credit)
—

 
0.1

 
(1.1
)
 
(1.1
)
Amortization of Net Actuarial Loss
1.1

 
1.1

 
0.5

 
0.4

Net Periodic Benefit Cost (Credit)
$
1.5

 
$
1.6

 
$
(1.0
)
 
$
(1.2
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
4.9

 
$
4.6

 
$
0.5

 
$
0.5

Interest Cost
8.0

 
8.4

 
2.4

 
2.4

Expected Return on Plan Assets
(11.8
)
 
(11.6
)
 
(4.2
)
 
(4.5
)
Amortization of Prior Service Cost (Credit)
—

 
0.2

 
(3.2
)
 
(3.2
)
Amortization of Net Actuarial Loss
3.3

 
3.3

 
1.5

 
1.3

Net Periodic Benefit Cost (Credit)
$
4.4

 
$
4.9

 
$
(3.0
)
 
$
(3.5
)


SWEPCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
2.1

 
$
2.0

 
$
0.2

 
$
0.2

Interest Cost
3.1

 
3.1

 
0.9

 
0.9

Expected Return on Plan Assets
(4.2
)
 
(4.0
)
 
(1.5
)
 
(1.7
)
Amortization of Prior Service Credit
—

 
—

 
(1.3
)
 
(1.3
)
Amortization of Net Actuarial Loss
1.3

 
1.2

 
0.5

 
0.5

Net Periodic Benefit Cost (Credit)
$
2.3

 
$
2.3

 
$
(1.2
)
 
$
(1.4
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
6.5

 
$
6.1

 
$
0.6

 
$
0.6

Interest Cost
9.2

 
9.3

 
2.7

 
2.7

Expected Return on Plan Assets
(12.6
)
 
(12.3
)
 
(4.7
)
 
(5.0
)
Amortization of Prior Service Cost (Credit)
—

 
0.2

 
(3.9
)
 
(3.9
)
Amortization of Net Actuarial Loss
3.7

 
3.6

 
1.7

 
1.5

Net Periodic Benefit Cost (Credit)
$
6.8

 
$
6.9

 
$
(3.6
)
 
$
(4.1
)
Public Service Co Of Oklahoma [Member]  
Benefit Plans
BENEFIT PLANS

The disclosures in this note apply to all Registrants except AEPTCo unless indicated otherwise.

AEP sponsors a qualified pension plan and two unfunded nonqualified pension plans.  Substantially all AEP employees are covered by the qualified plan or both the qualified and a nonqualified pension plan.  AEP also sponsors OPEB plans to provide health and life insurance benefits for retired employees.

Components of Net Periodic Benefit Cost

The following tables provide the components of net periodic benefit cost (credit) by Registrant for the plans:

AEP
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
24.1

 
$
21.4

 
$
2.8

 
$
2.6

Interest Cost
50.7

 
52.9

 
14.8

 
15.3

Expected Return on Plan Assets
(71.1
)
 
(70.1
)
 
(25.3
)
 
(26.8
)
Amortization of Prior Service Cost (Credit)
0.3

 
0.6

 
(17.3
)
 
(17.3
)
Amortization of Net Actuarial Loss
20.7

 
21.0

 
9.2

 
7.8

Net Periodic Benefit Cost (Credit)
$
24.7

 
$
25.8

 
$
(15.8
)
 
$
(18.4
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
72.3

 
$
64.3

 
$
8.4

 
$
7.7

Interest Cost
152.3

 
158.7

 
44.5

 
45.7

Expected Return on Plan Assets
(213.5
)
 
(210.2
)
 
(76.0
)
 
(80.3
)
Amortization of Prior Service Cost (Credit)
0.8

 
1.7

 
(51.8
)
 
(51.8
)
Amortization of Net Actuarial Loss
62.1

 
62.9

 
27.5

 
23.5

Net Periodic Benefit Cost (Credit)
$
74.0

 
$
77.4

 
$
(47.4
)
 
$
(55.2
)

APCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017

2016
 
2017
 
2016
 
(in millions)
Service Cost
$
2.3

 
$
2.1

 
$
0.3

 
$
0.2

Interest Cost
6.5

 
6.8

 
2.6

 
2.7

Expected Return on Plan Assets
(8.9
)
 
(8.8
)
 
(4.1
)
 
(4.3
)
Amortization of Prior Service Credit
—

 
—

 
(2.5
)
 
(2.5
)
Amortization of Net Actuarial Loss
2.6

 
2.6

 
1.6

 
1.4

Net Periodic Benefit Cost (Credit)
$
2.5

 
$
2.7

 
$
(2.1
)
 
$
(2.5
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
7.0

 
$
6.1

 
$
0.8

 
$
0.7

Interest Cost
19.3

 
20.4

 
7.9

 
8.1

Expected Return on Plan Assets
(26.8
)
 
(26.5
)
 
(12.3
)
 
(13.0
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(7.5
)
 
(7.5
)
Amortization of Net Actuarial Loss
7.8

 
8.0

 
4.7

 
4.1

Net Periodic Benefit Cost (Credit)
$
7.4

 
$
8.1

 
$
(6.4
)
 
$
(7.6
)


I&M
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
3.5

 
$
3.1

 
$
0.4

 
$
0.4

Interest Cost
6.1

 
6.3

 
1.7

 
1.7

Expected Return on Plan Assets
(8.6
)
 
(8.4
)
 
(3.1
)
 
(3.2
)
Amortization of Prior Service Credit
—

 
—

 
(2.3
)
 
(2.4
)
Amortization of Net Actuarial Loss
2.4

 
2.5

 
1.1

 
0.9

Net Periodic Benefit Cost (Credit)
$
3.4

 
$
3.5

 
$
(2.2
)
 
$
(2.6
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
10.5

 
$
9.2

 
$
1.2

 
$
1.1

Interest Cost
18.2

 
19.0

 
5.2

 
5.2

Expected Return on Plan Assets
(25.9
)
 
(25.2
)
 
(9.2
)
 
(9.6
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(7.0
)
 
(7.1
)
Amortization of Net Actuarial Loss
7.3

 
7.4

 
3.3

 
2.8

Net Periodic Benefit Cost (Credit)
$
10.2

 
$
10.5

 
$
(6.5
)
 
$
(7.6
)

OPCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
1.8

 
$
1.6

 
$
0.3

 
$
0.2

Interest Cost
4.8

 
5.1

 
1.6

 
1.8

Expected Return on Plan Assets
(6.9
)
 
(6.9
)
 
(3.0
)
 
(3.3
)
Amortization of Prior Service Credit
—

 
—

 
(1.7
)
 
(1.7
)
Amortization of Net Actuarial Loss
2.0

 
2.1

 
1.1

 
0.9

Net Periodic Benefit Cost (Credit)
$
1.7

 
$
1.9

 
$
(1.7
)
 
$
(2.1
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
5.6

 
$
4.9

 
$
0.7

 
$
0.6

Interest Cost
14.5

 
15.4

 
5.0

 
5.3

Expected Return on Plan Assets
(20.9
)
 
(20.8
)
 
(9.0
)
 
(9.7
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(5.2
)
 
(5.2
)
Amortization of Net Actuarial Loss
5.9

 
6.1

 
3.3

 
2.8

Net Periodic Benefit Cost (Credit)
$
5.2

 
$
5.7

 
$
(5.2
)
 
$
(6.2
)


PSO
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
1.7

 
$
1.5

 
$
0.2

 
$
0.2

Interest Cost
2.6

 
2.8

 
0.8

 
0.8

Expected Return on Plan Assets
(3.9
)
 
(3.9
)
 
(1.4
)
 
(1.5
)
Amortization of Prior Service Cost (Credit)
—

 
0.1

 
(1.1
)
 
(1.1
)
Amortization of Net Actuarial Loss
1.1

 
1.1

 
0.5

 
0.4

Net Periodic Benefit Cost (Credit)
$
1.5

 
$
1.6

 
$
(1.0
)
 
$
(1.2
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
4.9

 
$
4.6

 
$
0.5

 
$
0.5

Interest Cost
8.0

 
8.4

 
2.4

 
2.4

Expected Return on Plan Assets
(11.8
)
 
(11.6
)
 
(4.2
)
 
(4.5
)
Amortization of Prior Service Cost (Credit)
—

 
0.2

 
(3.2
)
 
(3.2
)
Amortization of Net Actuarial Loss
3.3

 
3.3

 
1.5

 
1.3

Net Periodic Benefit Cost (Credit)
$
4.4

 
$
4.9

 
$
(3.0
)
 
$
(3.5
)


SWEPCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
2.1

 
$
2.0

 
$
0.2

 
$
0.2

Interest Cost
3.1

 
3.1

 
0.9

 
0.9

Expected Return on Plan Assets
(4.2
)
 
(4.0
)
 
(1.5
)
 
(1.7
)
Amortization of Prior Service Credit
—

 
—

 
(1.3
)
 
(1.3
)
Amortization of Net Actuarial Loss
1.3

 
1.2

 
0.5

 
0.5

Net Periodic Benefit Cost (Credit)
$
2.3

 
$
2.3

 
$
(1.2
)
 
$
(1.4
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
6.5

 
$
6.1

 
$
0.6

 
$
0.6

Interest Cost
9.2

 
9.3

 
2.7

 
2.7

Expected Return on Plan Assets
(12.6
)
 
(12.3
)
 
(4.7
)
 
(5.0
)
Amortization of Prior Service Cost (Credit)
—

 
0.2

 
(3.9
)
 
(3.9
)
Amortization of Net Actuarial Loss
3.7

 
3.6

 
1.7

 
1.5

Net Periodic Benefit Cost (Credit)
$
6.8

 
$
6.9

 
$
(3.6
)
 
$
(4.1
)
Southwestern Electric Power Co [Member]  
Benefit Plans
BENEFIT PLANS

The disclosures in this note apply to all Registrants except AEPTCo unless indicated otherwise.

AEP sponsors a qualified pension plan and two unfunded nonqualified pension plans.  Substantially all AEP employees are covered by the qualified plan or both the qualified and a nonqualified pension plan.  AEP also sponsors OPEB plans to provide health and life insurance benefits for retired employees.

Components of Net Periodic Benefit Cost

The following tables provide the components of net periodic benefit cost (credit) by Registrant for the plans:

AEP
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
24.1

 
$
21.4

 
$
2.8

 
$
2.6

Interest Cost
50.7

 
52.9

 
14.8

 
15.3

Expected Return on Plan Assets
(71.1
)
 
(70.1
)
 
(25.3
)
 
(26.8
)
Amortization of Prior Service Cost (Credit)
0.3

 
0.6

 
(17.3
)
 
(17.3
)
Amortization of Net Actuarial Loss
20.7

 
21.0

 
9.2

 
7.8

Net Periodic Benefit Cost (Credit)
$
24.7

 
$
25.8

 
$
(15.8
)
 
$
(18.4
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
72.3

 
$
64.3

 
$
8.4

 
$
7.7

Interest Cost
152.3

 
158.7

 
44.5

 
45.7

Expected Return on Plan Assets
(213.5
)
 
(210.2
)
 
(76.0
)
 
(80.3
)
Amortization of Prior Service Cost (Credit)
0.8

 
1.7

 
(51.8
)
 
(51.8
)
Amortization of Net Actuarial Loss
62.1

 
62.9

 
27.5

 
23.5

Net Periodic Benefit Cost (Credit)
$
74.0

 
$
77.4

 
$
(47.4
)
 
$
(55.2
)

APCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017

2016
 
2017
 
2016
 
(in millions)
Service Cost
$
2.3

 
$
2.1

 
$
0.3

 
$
0.2

Interest Cost
6.5

 
6.8

 
2.6

 
2.7

Expected Return on Plan Assets
(8.9
)
 
(8.8
)
 
(4.1
)
 
(4.3
)
Amortization of Prior Service Credit
—

 
—

 
(2.5
)
 
(2.5
)
Amortization of Net Actuarial Loss
2.6

 
2.6

 
1.6

 
1.4

Net Periodic Benefit Cost (Credit)
$
2.5

 
$
2.7

 
$
(2.1
)
 
$
(2.5
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
7.0

 
$
6.1

 
$
0.8

 
$
0.7

Interest Cost
19.3

 
20.4

 
7.9

 
8.1

Expected Return on Plan Assets
(26.8
)
 
(26.5
)
 
(12.3
)
 
(13.0
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(7.5
)
 
(7.5
)
Amortization of Net Actuarial Loss
7.8

 
8.0

 
4.7

 
4.1

Net Periodic Benefit Cost (Credit)
$
7.4

 
$
8.1

 
$
(6.4
)
 
$
(7.6
)


I&M
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
3.5

 
$
3.1

 
$
0.4

 
$
0.4

Interest Cost
6.1

 
6.3

 
1.7

 
1.7

Expected Return on Plan Assets
(8.6
)
 
(8.4
)
 
(3.1
)
 
(3.2
)
Amortization of Prior Service Credit
—

 
—

 
(2.3
)
 
(2.4
)
Amortization of Net Actuarial Loss
2.4

 
2.5

 
1.1

 
0.9

Net Periodic Benefit Cost (Credit)
$
3.4

 
$
3.5

 
$
(2.2
)
 
$
(2.6
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
10.5

 
$
9.2

 
$
1.2

 
$
1.1

Interest Cost
18.2

 
19.0

 
5.2

 
5.2

Expected Return on Plan Assets
(25.9
)
 
(25.2
)
 
(9.2
)
 
(9.6
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(7.0
)
 
(7.1
)
Amortization of Net Actuarial Loss
7.3

 
7.4

 
3.3

 
2.8

Net Periodic Benefit Cost (Credit)
$
10.2

 
$
10.5

 
$
(6.5
)
 
$
(7.6
)

OPCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
1.8

 
$
1.6

 
$
0.3

 
$
0.2

Interest Cost
4.8

 
5.1

 
1.6

 
1.8

Expected Return on Plan Assets
(6.9
)
 
(6.9
)
 
(3.0
)
 
(3.3
)
Amortization of Prior Service Credit
—

 
—

 
(1.7
)
 
(1.7
)
Amortization of Net Actuarial Loss
2.0

 
2.1

 
1.1

 
0.9

Net Periodic Benefit Cost (Credit)
$
1.7

 
$
1.9

 
$
(1.7
)
 
$
(2.1
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
5.6

 
$
4.9

 
$
0.7

 
$
0.6

Interest Cost
14.5

 
15.4

 
5.0

 
5.3

Expected Return on Plan Assets
(20.9
)
 
(20.8
)
 
(9.0
)
 
(9.7
)
Amortization of Prior Service Cost (Credit)
0.1

 
0.1

 
(5.2
)
 
(5.2
)
Amortization of Net Actuarial Loss
5.9

 
6.1

 
3.3

 
2.8

Net Periodic Benefit Cost (Credit)
$
5.2

 
$
5.7

 
$
(5.2
)
 
$
(6.2
)


PSO
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
1.7

 
$
1.5

 
$
0.2

 
$
0.2

Interest Cost
2.6

 
2.8

 
0.8

 
0.8

Expected Return on Plan Assets
(3.9
)
 
(3.9
)
 
(1.4
)
 
(1.5
)
Amortization of Prior Service Cost (Credit)
—

 
0.1

 
(1.1
)
 
(1.1
)
Amortization of Net Actuarial Loss
1.1

 
1.1

 
0.5

 
0.4

Net Periodic Benefit Cost (Credit)
$
1.5

 
$
1.6

 
$
(1.0
)
 
$
(1.2
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
4.9

 
$
4.6

 
$
0.5

 
$
0.5

Interest Cost
8.0

 
8.4

 
2.4

 
2.4

Expected Return on Plan Assets
(11.8
)
 
(11.6
)
 
(4.2
)
 
(4.5
)
Amortization of Prior Service Cost (Credit)
—

 
0.2

 
(3.2
)
 
(3.2
)
Amortization of Net Actuarial Loss
3.3

 
3.3

 
1.5

 
1.3

Net Periodic Benefit Cost (Credit)
$
4.4

 
$
4.9

 
$
(3.0
)
 
$
(3.5
)


SWEPCo
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Three Months Ended September 30,
 
Three Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
2.1

 
$
2.0

 
$
0.2

 
$
0.2

Interest Cost
3.1

 
3.1

 
0.9

 
0.9

Expected Return on Plan Assets
(4.2
)
 
(4.0
)
 
(1.5
)
 
(1.7
)
Amortization of Prior Service Credit
—

 
—

 
(1.3
)
 
(1.3
)
Amortization of Net Actuarial Loss
1.3

 
1.2

 
0.5

 
0.5

Net Periodic Benefit Cost (Credit)
$
2.3

 
$
2.3

 
$
(1.2
)
 
$
(1.4
)
 
Pension Plans
 
Other Postretirement
Benefit Plans
 
Nine Months Ended September 30,
 
Nine Months Ended September 30,
 
2017
 
2016
 
2017
 
2016
 
(in millions)
Service Cost
$
6.5

 
$
6.1

 
$
0.6

 
$
0.6

Interest Cost
9.2

 
9.3

 
2.7

 
2.7

Expected Return on Plan Assets
(12.6
)
 
(12.3
)
 
(4.7
)
 
(5.0
)
Amortization of Prior Service Cost (Credit)
—

 
0.2

 
(3.9
)
 
(3.9
)
Amortization of Net Actuarial Loss
3.7

 
3.6

 
1.7

 
1.5

Net Periodic Benefit Cost (Credit)
$
6.8

 
$
6.9

 
$
(3.6
)
 
$
(4.1
)