Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2016

Components of Net Periodic Benefit Cost

AEP

	Pension Plans						Other Postretirement Benefit Plans
	Three Months Ended June 30,						Three Months Ended June 30,
	2016			2015			2016			2015
	(in millions)
Service Cost	$	21.5		$	23.4		$	2.5		$	3.0
Interest Cost	52.9			51.3			15.2			14.2
Expected Return on Plan Assets	(70.0		)	(68.7		)	(26.7		)	(27.8		)
Amortization of Prior Service Cost (Credit)	0.5			0.6			(17.2		)	(17.2		)
Amortization of Net Actuarial Loss	20.9			26.8			7.8			4.7
Net Periodic Benefit Cost (Credit)	$	25.8		$	33.4		$	(18.4	)	$	(23.1	)

	Pension Plans						Other Postretirement Benefit Plans
	Six Months Ended June 30,						Six Months Ended June 30,
	2016			2015			2016			2015
	(in millions)
Service Cost	$	42.9		$	46.7		$	5.1		$	6.1
Interest Cost	105.8			102.6			30.4			28.4
Expected Return on Plan Assets	(140.1		)	(137.4		)	(53.5		)	(55.6		)
Amortization of Prior Service Cost (Credit)	1.1			1.2			(34.5		)	(34.5		)
Amortization of Net Actuarial Loss	41.9			53.6			15.7			9.4
Net Periodic Benefit Cost (Credit)	$	51.6		$	66.7		$	(36.8	)	$	(46.2	)

Appalachian Power Co [Member]

Components of Net Periodic Benefit Cost

APCo

	Pension Plans						Other Postretirement Benefit Plans
	Three Months Ended June 30,						Three Months Ended June 30,
	2016			2015			2016			2015
	(in millions)
Service Cost	$	2.0		$	2.2		$	0.3		$	0.3
Interest Cost	6.8			6.7			2.7			2.6
Expected Return on Plan Assets	(8.9		)	(8.7		)	(4.4		)	(4.5		)
Amortization of Prior Service Cost (Credit)	0.1			0.1			(2.5		)	(2.5		)
Amortization of Net Actuarial Loss	2.7			3.4			1.3			0.9
Net Periodic Benefit Cost (Credit)	$	2.7		$	3.7		$	(2.6	)	$	(3.2	)

	Pension Plans						Other Postretirement Benefit Plans
	Six Months Ended June 30,						Six Months Ended June 30,
	2016			2015			2016			2015
	(in millions)
Service Cost	$	4.0		$	4.4		$	0.5		$	0.6
Interest Cost	13.6			13.4			5.4			5.2
Expected Return on Plan Assets	(17.7		)	(17.5		)	(8.7		)	(9.1		)
Amortization of Prior Service Cost (Credit)	0.1			0.1			(5.0		)	(5.0		)
Amortization of Net Actuarial Loss	5.4			6.9			2.7			1.8
Net Periodic Benefit Cost (Credit)	$	5.4		$	7.3		$	(5.1	)	$	(6.5	)

Indiana Michigan Power Co [Member]

Components of Net Periodic Benefit Cost

I&M

	Pension Plans						Other Postretirement Benefit Plans
	Three Months Ended June 30,						Three Months Ended June 30,
	2016			2015			2016			2015
	(in millions)
Service Cost	$	3.1		$	3.2		$	0.3		$	0.4
Interest Cost	6.4			6.1			1.7			1.6
Expected Return on Plan Assets	(8.4		)	(8.1		)	(3.2		)	(3.3		)
Amortization of Prior Service Cost (Credit)	—			0.1			(2.3		)	(2.3		)
Amortization of Net Actuarial Loss	2.4			3.1			1.0			0.5
Net Periodic Benefit Cost (Credit)	$	3.5		$	4.4		$	(2.5	)	$	(3.1	)

	Pension Plans						Other Postretirement Benefit Plans
	Six Months Ended June 30,						Six Months Ended June 30,
	2016			2015			2016			2015
	(in millions)
Service Cost	$	6.1		$	6.4		$	0.7		$	0.8
Interest Cost	12.7			12.2			3.5			3.2
Expected Return on Plan Assets	(16.8		)	(16.2		)	(6.4		)	(6.6		)
Amortization of Prior Service Cost (Credit)	0.1			0.1			(4.7		)	(4.7		)
Amortization of Net Actuarial Loss	4.9			6.3			1.9			1.0
Net Periodic Benefit Cost (Credit)	$	7.0		$	8.8		$	(5.0	)	$	(6.3	)

Ohio Power Co [Member]

Components of Net Periodic Benefit Cost

OPCo

	Pension Plans						Other Postretirement Benefit Plans
	Three Months Ended June 30,						Three Months Ended June 30,
	2016			2015			2016			2015
	(in millions)
Service Cost	$	1.7		$	1.7		$	0.2		$	0.2
Interest Cost	5.1			5.0			1.8			1.6
Expected Return on Plan Assets	(7.0		)	(6.9		)	(3.2		)	(3.3		)
Amortization of Prior Service Cost (Credit)	0.1			0.1			(1.8		)	(1.7		)
Amortization of Net Actuarial Loss	2.0			2.7			1.0			0.5
Net Periodic Benefit Cost (Credit)	$	1.9		$	2.6		$	(2.0	)	$	(2.7	)

	Pension Plans						Other Postretirement Benefit Plans
	Six Months Ended June 30,						Six Months Ended June 30,
	2016			2015			2016			2015
	(in millions)
Service Cost	$	3.3		$	3.4		$	0.4		$	0.4
Interest Cost	10.3			10.1			3.5			3.2
Expected Return on Plan Assets	(13.9		)	(13.8		)	(6.4		)	(6.7		)
Amortization of Prior Service Cost (Credit)	0.1			0.1			(3.5		)	(3.4		)
Amortization of Net Actuarial Loss	4.0			5.3			1.9			1.0
Net Periodic Benefit Cost (Credit)	$	3.8		$	5.1		$	(4.1	)	$	(5.5	)

Public Service Co Of Oklahoma [Member]

Components of Net Periodic Benefit Cost

PSO

	Pension Plans						Other Postretirement Benefit Plans
	Three Months Ended June 30,						Three Months Ended June 30,
	2016			2015			2016			2015
	(in millions)
Service Cost	$	1.6		$	1.6		$	0.1		$	0.1
Interest Cost	2.8			2.8			0.8			0.7
Expected Return on Plan Assets	(3.8		)	(3.8		)	(1.5		)	(1.6		)
Amortization of Prior Service Credit	—			—			(1.0		)	(1.0		)
Amortization of Net Actuarial Loss	1.1			1.4			0.5			0.3
Net Periodic Benefit Cost (Credit)	$	1.7		$	2.0		$	(1.1	)	$	(1.5	)

	Pension Plans						Other Postretirement Benefit Plans
	Six Months Ended June 30,						Six Months Ended June 30,
	2016			2015			2016			2015
	(in millions)
Service Cost	$	3.1		$	3.2		$	0.3		$	0.3
Interest Cost	5.6			5.5			1.6			1.5
Expected Return on Plan Assets	(7.7		)	(7.6		)	(3.0		)	(3.2		)
Amortization of Prior Service Cost (Credit)	0.1			0.1			(2.1		)	(2.1		)
Amortization of Net Actuarial Loss	2.2			2.8			0.9			0.5
Net Periodic Benefit Cost (Credit)	$	3.3		$	4.0		$	(2.3	)	$	(3.0	)

Southwestern Electric Power Co [Member]

Components of Net Periodic Benefit Cost

SWEPCo

	Pension Plans						Other Postretirement Benefit Plans
	Three Months Ended June 30,						Three Months Ended June 30,
	2016			2015			2016			2015
	(in millions)
Service Cost	$	2.1		$	2.0		$	0.2		$	0.2
Interest Cost	3.1			3.0			0.9			0.9
Expected Return on Plan Assets	(4.2		)	(4.0		)	(1.6		)	(1.8		)
Amortization of Prior Service Cost (Credit)	0.1			0.1			(1.3		)	(1.2		)
Amortization of Net Actuarial Loss	1.2			1.5			0.5			0.2
Net Periodic Benefit Cost (Credit)	$	2.3		$	2.6		$	(1.3	)	$	(1.7	)

	Pension Plans						Other Postretirement Benefit Plans
	Six Months Ended June 30,						Six Months Ended June 30,
	2016			2015			2016			2015
	(in millions)
Service Cost	$	4.1		$	4.1		$	0.4		$	0.4
Interest Cost	6.2			5.9			1.8			1.7
Expected Return on Plan Assets	(8.3		)	(8.0		)	(3.3		)	(3.5		)
Amortization of Prior Service Cost (Credit)	0.2			0.2			(2.6		)	(2.5		)
Amortization of Net Actuarial Loss	2.4			3.0			1.0			0.5
Net Periodic Benefit Cost (Credit)	$	4.6		$	5.2		$	(2.7	)	$	(3.4	)