Income Taxes Income Taxes (Tables)

9 Months Ended

Sep. 30, 2017

Summary of Effective Tax Rate

	Three Months Ended September 30,				Nine Months Ended September 30,
Company	2017		2016		2017		2016
AEP	33.0	%	40.4	%	35.3	%	(195.6	)%
AEPTCo	33.5	%	33.5	%	33.8	%	32.6	%
APCo	33.4	%	36.1	%	35.5	%	36.2	%
I&M	30.6	%	31.8	%	30.1	%	29.5	%
OPCo	36.9	%	31.7	%	35.6	%	33.4	%
PSO	37.2	%	37.7	%	37.4	%	36.8	%
SWEPCo	21.2	%	28.9	%	25.7	%	26.7	%

AEP Transmission Co [Member]

Summary of Effective Tax Rate

	Three Months Ended September 30,				Nine Months Ended September 30,
Company	2017		2016		2017		2016
AEP	33.0	%	40.4	%	35.3	%	(195.6	)%
AEPTCo	33.5	%	33.5	%	33.8	%	32.6	%
APCo	33.4	%	36.1	%	35.5	%	36.2	%
I&M	30.6	%	31.8	%	30.1	%	29.5	%
OPCo	36.9	%	31.7	%	35.6	%	33.4	%
PSO	37.2	%	37.7	%	37.4	%	36.8	%
SWEPCo	21.2	%	28.9	%	25.7	%	26.7	%

Appalachian Power Co [Member]

Summary of Effective Tax Rate

	Three Months Ended September 30,				Nine Months Ended September 30,
Company	2017		2016		2017		2016
AEP	33.0	%	40.4	%	35.3	%	(195.6	)%
AEPTCo	33.5	%	33.5	%	33.8	%	32.6	%
APCo	33.4	%	36.1	%	35.5	%	36.2	%
I&M	30.6	%	31.8	%	30.1	%	29.5	%
OPCo	36.9	%	31.7	%	35.6	%	33.4	%
PSO	37.2	%	37.7	%	37.4	%	36.8	%
SWEPCo	21.2	%	28.9	%	25.7	%	26.7	%

Indiana Michigan Power Co [Member]

Summary of Effective Tax Rate

	Three Months Ended September 30,				Nine Months Ended September 30,
Company	2017		2016		2017		2016
AEP	33.0	%	40.4	%	35.3	%	(195.6	)%
AEPTCo	33.5	%	33.5	%	33.8	%	32.6	%
APCo	33.4	%	36.1	%	35.5	%	36.2	%
I&M	30.6	%	31.8	%	30.1	%	29.5	%
OPCo	36.9	%	31.7	%	35.6	%	33.4	%
PSO	37.2	%	37.7	%	37.4	%	36.8	%
SWEPCo	21.2	%	28.9	%	25.7	%	26.7	%

Ohio Power Co [Member]

Summary of Effective Tax Rate

	Three Months Ended September 30,				Nine Months Ended September 30,
Company	2017		2016		2017		2016
AEP	33.0	%	40.4	%	35.3	%	(195.6	)%
AEPTCo	33.5	%	33.5	%	33.8	%	32.6	%
APCo	33.4	%	36.1	%	35.5	%	36.2	%
I&M	30.6	%	31.8	%	30.1	%	29.5	%
OPCo	36.9	%	31.7	%	35.6	%	33.4	%
PSO	37.2	%	37.7	%	37.4	%	36.8	%
SWEPCo	21.2	%	28.9	%	25.7	%	26.7	%

Public Service Co Of Oklahoma [Member]

Summary of Effective Tax Rate

	Three Months Ended September 30,				Nine Months Ended September 30,
Company	2017		2016		2017		2016
AEP	33.0	%	40.4	%	35.3	%	(195.6	)%
AEPTCo	33.5	%	33.5	%	33.8	%	32.6	%
APCo	33.4	%	36.1	%	35.5	%	36.2	%
I&M	30.6	%	31.8	%	30.1	%	29.5	%
OPCo	36.9	%	31.7	%	35.6	%	33.4	%
PSO	37.2	%	37.7	%	37.4	%	36.8	%
SWEPCo	21.2	%	28.9	%	25.7	%	26.7	%

Southwestern Electric Power Co [Member]

Summary of Effective Tax Rate

	Three Months Ended September 30,				Nine Months Ended September 30,
Company	2017		2016		2017		2016
AEP	33.0	%	40.4	%	35.3	%	(195.6	)%
AEPTCo	33.5	%	33.5	%	33.8	%	32.6	%
APCo	33.4	%	36.1	%	35.5	%	36.2	%
I&M	30.6	%	31.8	%	30.1	%	29.5	%
OPCo	36.9	%	31.7	%	35.6	%	33.4	%
PSO	37.2	%	37.7	%	37.4	%	36.8	%
SWEPCo	21.2	%	28.9	%	25.7	%	26.7	%