Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Pension Plans [Member]
Components of Net Periodic Benefit Cost
Service Cost	$ 23,000	$ 18,000
Interest Cost	51,000	55,000
Expected Return on Plan Assets	(69,000)	(66,000)
Amortization of Prior Service Cost (Credit)	1,000	1,000
Amortization of Net Actuarial Loss	27,000	31,000
Net Periodic Benefit Cost (Credit)	33,000	39,000
Pension Plans [Member] | Appalachian Power Co [Member]
Components of Net Periodic Benefit Cost
Service Cost	2,175	1,759
Interest Cost	6,679	7,406
Expected Return on Plan Assets	(8,745)	(8,482)
Amortization of Prior Service Cost (Credit)	45	50
Amortization of Net Actuarial Loss	3,473	4,148
Net Periodic Benefit Cost (Credit)	3,627	4,881
Pension Plans [Member] | Indiana Michigan Power Co [Member]
Components of Net Periodic Benefit Cost
Service Cost	3,217	2,517
Interest Cost	6,115	6,573
Expected Return on Plan Assets	(8,116)	(7,748)
Amortization of Prior Service Cost (Credit)	45	49
Amortization of Net Actuarial Loss	3,145	3,646
Net Periodic Benefit Cost (Credit)	4,406	5,037
Pension Plans [Member] | Ohio Power Co [Member]
Components of Net Periodic Benefit Cost
Service Cost	1,672	1,285
Interest Cost	5,070	5,526
Expected Return on Plan Assets	(6,878)	(6,607)
Amortization of Prior Service Cost (Credit)	35	39
Amortization of Net Actuarial Loss	2,644	3,106
Net Periodic Benefit Cost (Credit)	2,543	3,349
Pension Plans [Member] | Public Service Co Of Oklahoma [Member]
Components of Net Periodic Benefit Cost
Service Cost	1,599	1,302
Interest Cost	2,731	3,014
Expected Return on Plan Assets	(3,786)	(3,651)
Amortization of Prior Service Cost (Credit)	63	74
Amortization of Net Actuarial Loss	1,417	1,688
Net Periodic Benefit Cost (Credit)	2,024	2,427
Pension Plans [Member] | Southwestern Electric Power Co [Member]
Components of Net Periodic Benefit Cost
Service Cost	2,081	1,655
Interest Cost	2,932	3,163
Expected Return on Plan Assets	(4,008)	(3,857)
Amortization of Prior Service Cost (Credit)	77	87
Amortization of Net Actuarial Loss	1,507	1,761
Net Periodic Benefit Cost (Credit)	2,589	2,809
Other Postretirement Benefit Plans [Member]
Components of Net Periodic Benefit Cost
Service Cost	3,000	4,000
Interest Cost	14,000	17,000
Expected Return on Plan Assets	(28,000)	(28,000)
Amortization of Prior Service Cost (Credit)	(17,000)	(17,000)
Amortization of Net Actuarial Loss	5,000	5,000
Net Periodic Benefit Cost (Credit)	(23,000)	(19,000)
Other Postretirement Benefit Plans [Member] | Appalachian Power Co [Member]
Components of Net Periodic Benefit Cost
Service Cost	286	362
Interest Cost	2,584	3,197
Expected Return on Plan Assets	(4,529)	(4,633)
Amortization of Prior Service Cost (Credit)	(2,513)	(2,513)
Amortization of Net Actuarial Loss	900	1,146
Net Periodic Benefit Cost (Credit)	(3,272)	(2,441)
Other Postretirement Benefit Plans [Member] | Indiana Michigan Power Co [Member]
Components of Net Periodic Benefit Cost
Service Cost	406	487
Interest Cost	1,592	1,909
Expected Return on Plan Assets	(3,304)	(3,364)
Amortization of Prior Service Cost (Credit)	(2,355)	(2,355)
Amortization of Net Actuarial Loss	506	592
Net Periodic Benefit Cost (Credit)	(3,155)	(2,731)
Other Postretirement Benefit Plans [Member] | Ohio Power Co [Member]
Components of Net Periodic Benefit Cost
Service Cost	216	256
Interest Cost	1,615	1,901
Expected Return on Plan Assets	(3,376)	(3,380)
Amortization of Prior Service Cost (Credit)	(1,731)	(1,731)
Amortization of Net Actuarial Loss	517	595
Net Periodic Benefit Cost (Credit)	(2,759)	(2,359)
Other Postretirement Benefit Plans [Member] | Public Service Co Of Oklahoma [Member]
Components of Net Periodic Benefit Cost
Service Cost	170	210
Interest Cost	759	893
Expected Return on Plan Assets	(1,577)	(1,575)
Amortization of Prior Service Cost (Credit)	(1,073)	(1,072)
Amortization of Net Actuarial Loss	242	277
Net Periodic Benefit Cost (Credit)	(1,479)	(1,267)
Other Postretirement Benefit Plans [Member] | Southwestern Electric Power Co [Member]
Components of Net Periodic Benefit Cost
Service Cost	211	253
Interest Cost	837	998
Expected Return on Plan Assets	(1,735)	(1,754)
Amortization of Prior Service Cost (Credit)	(1,289)	(1,289)
Amortization of Net Actuarial Loss	266	309
Net Periodic Benefit Cost (Credit)	$ (1,710)	$ (1,483)