Variable Interest Entities (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended			12 Months Ended
		Sep. 30, 2015		Sep. 30, 2014	Sep. 30, 2015		Sep. 30, 2014	Dec. 31, 2014
Variable Interest Entities (Textuals) [Abstract]
Securitization Bonds		$ 2,072,000			$ 2,072,000			$ 2,380,000
Securitized Transition Assets		1,841,000			$ 1,841,000			2,072,000
AEP Credit, Inc. [Member]
Variable Interest Entities (Textuals) [Abstract]
Minimum Percentage of Equity AEP Provides					5.00%
Percentage of Short Term Borrowing Needs in Excess of Third Party Financings					20.00%
AEP Texas Central Transition Funding Co [Member]
Variable Interest Entities (Textuals) [Abstract]
Securitization Bonds		1,500,000			$ 1,500,000			1,800,000
Securitized Transition Assets		1,400,000			1,400,000			1,600,000
Protected Cell Of Energy Insurance Services, Inc. [Member]
Variable Interest Entities (Textuals) [Abstract]
Insurance Premium Expense to Protected Cell		13,000		$ 16,000	27,000		$ 33,000
Transource Energy [Member]
Variable Interest Entities (Textuals) [Abstract]
Proceeds from Partnership Contribution					32,000			23,000
PATH West Virginia Transmission Co, LLC [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet		21,000			21,000			21,000
Maximum Exposure		21,000			21,000			21,000
Advance Due to Parent [Member] | Dolet Hills Lignite Co, LLC [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet		40,000			40,000			56,000
Maximum Exposure		40,000			40,000			56,000
Capital Contribution From Parent [Member] | PATH West Virginia Transmission Co, LLC [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet		19,000			19,000			19,000
Maximum Exposure		19,000			19,000			19,000
Retained Earnings [Member] | PATH West Virginia Transmission Co, LLC [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet		2,000			2,000			2,000
Maximum Exposure		2,000			2,000			2,000
SWEPCo's Guarantee Of Debt [Member] | Dolet Hills Lignite Co, LLC [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet		0			0			0
Maximum Exposure		55,000			55,000			48,000
Current Assets [Member] | AEP Credit, Inc. [Member]
ASSETS
Assets		977,000			977,000			980,000
Current Assets [Member] | AEP Texas Central Transition Funding Co [Member]
ASSETS
Assets		197,000			197,000			239,000
Current Assets [Member] | Protected Cell Of Energy Insurance Services, Inc. [Member]
ASSETS
Assets		163,000			163,000			149,000
Current Assets [Member] | Transource Energy [Member]
ASSETS
Assets		12,000			12,000			2,000
Net Property Plant And Equipment [Member] | AEP Credit, Inc. [Member]
ASSETS
Assets		0			0			0
Net Property Plant And Equipment [Member] | AEP Texas Central Transition Funding Co [Member]
ASSETS
Assets		0			0			0
Net Property Plant And Equipment [Member] | Protected Cell Of Energy Insurance Services, Inc. [Member]
ASSETS
Assets		0			0			0
Net Property Plant And Equipment [Member] | Transource Energy [Member]
ASSETS
Assets		184,000			184,000			98,000
Other Non Current Assets [Member] | AEP Credit, Inc. [Member]
ASSETS
Assets		1,000			1,000			0
Other Non Current Assets [Member] | AEP Texas Central Transition Funding Co [Member]
ASSETS
Assets		1,454,000	[1]		1,454,000	[1]		1,654,000	[2]
Variable Interest Entities (Textuals) [Abstract]
Intercompany Item Eliminated in Consolidation		70,000			70,000			75,000
Other Non Current Assets [Member] | Protected Cell Of Energy Insurance Services, Inc. [Member]
ASSETS
Assets		3,000			3,000			2,000
Other Non Current Assets [Member] | Transource Energy [Member]
ASSETS
Assets		5,000			5,000			4,000
Total Assets [Member] | AEP Credit, Inc. [Member]
ASSETS
Assets		978,000			978,000			980,000
Total Assets [Member] | AEP Texas Central Transition Funding Co [Member]
ASSETS
Assets		1,651,000			1,651,000			1,893,000
Total Assets [Member] | Protected Cell Of Energy Insurance Services, Inc. [Member]
ASSETS
Assets		166,000			166,000			151,000
Total Assets [Member] | Transource Energy [Member]
ASSETS
Assets		201,000			201,000			104,000
Current Liabilities [Member] | AEP Credit, Inc. [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		875,000			875,000			894,000
Current Liabilities [Member] | AEP Texas Central Transition Funding Co [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		283,000			283,000			322,000
Current Liabilities [Member] | Protected Cell Of Energy Insurance Services, Inc. [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		49,000			49,000			44,000
Current Liabilities [Member] | Transource Energy [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		47,000			47,000			21,000
Noncurrent Liabilities [Member] | AEP Credit, Inc. [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		1,000			1,000			0
Noncurrent Liabilities [Member] | AEP Texas Central Transition Funding Co [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		1,350,000			1,350,000			1,553,000
Noncurrent Liabilities [Member] | Protected Cell Of Energy Insurance Services, Inc. [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		76,000			76,000			62,000
Noncurrent Liabilities [Member] | Transource Energy [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		80,000			80,000			55,000
Equity [Member] | AEP Credit, Inc. [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		102,000			102,000			86,000
Equity [Member] | AEP Texas Central Transition Funding Co [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		18,000			18,000			18,000
Equity [Member] | Protected Cell Of Energy Insurance Services, Inc. [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		41,000			41,000			45,000
Equity [Member] | Transource Energy [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		74,000			74,000			28,000
Total Liabilities And Equity [Member] | AEP Credit, Inc. [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		978,000			978,000			980,000
Total Liabilities And Equity [Member] | AEP Texas Central Transition Funding Co [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		1,651,000			1,651,000			1,893,000
Total Liabilities And Equity [Member] | Protected Cell Of Energy Insurance Services, Inc. [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		166,000			166,000			151,000
Total Liabilities And Equity [Member] | Transource Energy [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		$ 201,000			$ 201,000			104,000
Great Plains Energy Inc. [Member] | Transource Energy [Member]
Variable Interest Entities (Textuals) [Abstract]
Equity and Voting Ownership Percentage		13.50%			13.50%
Transource Energy [Member]
Variable Interest Entities (Textuals) [Abstract]
Equity and Voting Ownership Percentage		86.50%			86.50%
Appalachian Power Co [Member]
Related Party Transaction, Due from (to) Related Party, Current		$ (11,689)			$ (11,689)
Variable Interest Entities (Textuals) [Abstract]
Securitized Transition Assets		333,491			333,491			350,170
Appalachian Power Co [Member] | Appalachian Consumer Rate Relief Funding [Member]
Variable Interest Entities (Textuals) [Abstract]
Securitization Bonds		345,000			345,000			368,000
Securitized Transition Assets		333,000			333,000			350,000
Intercompany Item Eliminated in Consolidation		4,000			4,000			4,000
Appalachian Power Co [Member] | Billings from American Electric Power Service Corporation [Member]
Billings from Affiliates
Billings from VIE		63,687		50,143	164,657		154,239
Variable Interest Entities (Textuals) [Abstract]
Billings from VIE		63,687		50,143	164,657		154,239
Appalachian Power Co [Member] | Carrying Amount in AEPSC's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet		23,783			23,783			30,692
Maximum Exposure		23,783			23,783			30,692
Appalachian Power Co [Member] | Current Assets [Member] | Appalachian Consumer Rate Relief Funding [Member]
ASSETS
Assets		10,914			10,914			18,099
Appalachian Power Co [Member] | Other Non Current Assets [Member] | Appalachian Consumer Rate Relief Funding [Member]
ASSETS
Assets	[3]	341,127			341,127			358,264
Appalachian Power Co [Member] | Total Assets [Member] | Appalachian Consumer Rate Relief Funding [Member]
ASSETS
Assets		352,041			352,041			376,363
Appalachian Power Co [Member] | Current Liabilities [Member] | Appalachian Consumer Rate Relief Funding [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		24,617			24,617			26,809
Appalachian Power Co [Member] | Noncurrent Liabilities [Member] | Appalachian Consumer Rate Relief Funding [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		325,534			325,534			347,652
Appalachian Power Co [Member] | Equity [Member] | Appalachian Consumer Rate Relief Funding [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		1,890			1,890			1,902
Appalachian Power Co [Member] | Total Liabilities And Equity [Member] | Appalachian Consumer Rate Relief Funding [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		352,041			352,041			376,363
Indiana Michigan Power Co [Member]
Related Party Transaction, Due from (to) Related Party, Current		(137,496)			(137,496)
Indiana Michigan Power Co [Member] | DCC Fuel [Member]
Variable Interest Entities (Textuals) [Abstract]
Payments Made by I&M to DCC Fuel		29,000		28,000	86,000		84,000
Indiana Michigan Power Co [Member] | Billings from AEP Generating Co [Member]
Billings from Affiliates
Billings from VIE		67,000		67,000	182,000		202,000
Variable Interest Entities (Textuals) [Abstract]
Billings from VIE		67,000		67,000	182,000		202,000
Indiana Michigan Power Co [Member] | Billings from American Electric Power Service Corporation [Member]
Billings from Affiliates
Billings from VIE		37,506		30,613	102,141		92,686
Variable Interest Entities (Textuals) [Abstract]
Billings from VIE		37,506		30,613	102,141		92,686
Indiana Michigan Power Co [Member] | Carrying Amount in AEPSC's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet		13,676			13,676			22,480
Maximum Exposure		13,676			13,676			22,480
Indiana Michigan Power Co [Member] | Current Assets [Member] | DCC Fuel [Member]
ASSETS
Assets		104,273			104,273			97,361
Indiana Michigan Power Co [Member] | Net Property Plant And Equipment [Member] | DCC Fuel [Member]
ASSETS
Assets		193,447			193,447			158,121
Indiana Michigan Power Co [Member] | Other Non Current Assets [Member] | DCC Fuel [Member]
ASSETS
Assets		99,811			99,811			79,705
Indiana Michigan Power Co [Member] | Total Assets [Member] | DCC Fuel [Member]
ASSETS
Assets		397,531			397,531			335,187
Indiana Michigan Power Co [Member] | Current Liabilities [Member] | DCC Fuel [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		98,173			98,173			86,026
Indiana Michigan Power Co [Member] | Noncurrent Liabilities [Member] | DCC Fuel [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		299,358			299,358			249,161
Indiana Michigan Power Co [Member] | Total Liabilities And Equity [Member] | DCC Fuel [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		397,531			397,531			335,187
Public Service Co Of Oklahoma [Member]
Related Party Transaction, Due from (to) Related Party, Current		116,345			116,345
Public Service Co Of Oklahoma [Member] | Billings from American Electric Power Service Corporation [Member]
Billings from Affiliates
Billings from VIE		29,851		24,317	77,817		71,646
Variable Interest Entities (Textuals) [Abstract]
Billings from VIE		29,851		24,317	77,817		71,646
Public Service Co Of Oklahoma [Member] | Carrying Amount in AEPSC's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet		10,713			10,713			15,338
Maximum Exposure		10,713			10,713			15,338
Southwestern Electric Power Co [Member]
Related Party Transaction, Due from (to) Related Party, Current		43,073			43,073
Southwestern Electric Power Co [Member] | Sabine Mining Co [Member]
Billings from Affiliates
Billings from VIE		41,000		41,000	124,000		121,000
Variable Interest Entities (Textuals) [Abstract]
Billings from VIE		41,000		41,000	124,000		121,000
Southwestern Electric Power Co [Member] | Dolet Hills Lignite Co, LLC [Member]
Related Party Transaction, Due from (to) Related Party, Current		40,000			40,000			56,000
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet		13,593			13,593			11,462
Maximum Exposure		108,773			108,773			115,796
Billings from Affiliates
Billings from VIE		30,000		24,000	59,000		31,000
Variable Interest Entities (Textuals) [Abstract]
Billings from VIE		30,000		24,000	$ 59,000		31,000
Percentage of VIE Sales of Lignite Produced					50.00%
Percentage of DHLCs Debt Guaranteed by Each SWEPCo and CLECO					50.00%
Percentage Of VIE Management Fee Received					100.00%
Southwestern Electric Power Co [Member] | Billings from American Electric Power Service Corporation [Member]
Billings from Affiliates
Billings from VIE		39,150		32,787	$ 102,564		98,528
Variable Interest Entities (Textuals) [Abstract]
Billings from VIE		39,150		32,787	102,564		98,528
Southwestern Electric Power Co [Member] | Carrying Amount in AEPSC's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet		14,295			14,295			20,772
Maximum Exposure		14,295			14,295			20,772
Southwestern Electric Power Co [Member] | Capital Contribution From Parent [Member] | Dolet Hills Lignite Co, LLC [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet		7,643			7,643			7,643
Maximum Exposure		7,643			7,643			7,643
Southwestern Electric Power Co [Member] | Retained Earnings [Member] | Dolet Hills Lignite Co, LLC [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet		5,950			5,950			3,819
Maximum Exposure		5,950			5,950			3,819
Southwestern Electric Power Co [Member] | SWEPCo's Guarantee Of Debt [Member] | Dolet Hills Lignite Co, LLC [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet		0			0			0
Maximum Exposure	[4]	95,180			95,180			104,334
Southwestern Electric Power Co [Member] | Current Assets [Member] | Sabine Mining Co [Member]
ASSETS
Assets		61,025			61,025			67,981
Southwestern Electric Power Co [Member] | Net Property Plant And Equipment [Member] | Sabine Mining Co [Member]
ASSETS
Assets		143,815			143,815			145,491
Southwestern Electric Power Co [Member] | Other Non Current Assets [Member] | Sabine Mining Co [Member]
ASSETS
Assets		60,160			60,160			51,578
Southwestern Electric Power Co [Member] | Total Assets [Member] | Sabine Mining Co [Member]
ASSETS
Assets		265,000			265,000			265,050
Southwestern Electric Power Co [Member] | Current Liabilities [Member] | Sabine Mining Co [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		40,311			40,311			36,286
Southwestern Electric Power Co [Member] | Noncurrent Liabilities [Member] | Sabine Mining Co [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		224,371			224,371			228,349
Southwestern Electric Power Co [Member] | Equity [Member] | Sabine Mining Co [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		318			318			415
Southwestern Electric Power Co [Member] | Total Liabilities And Equity [Member] | Sabine Mining Co [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		$ 265,000			$ 265,000			265,050
AEP Generating Co [Member] | Rockport Generating Plant (Unit No. 1) [Member]
Variable Interest Entities (Textuals) [Abstract]
Jointly Owned Utility Plant, Proportionate Ownership Share		50.00%			50.00%
AEP Generating Co [Member] | Rockport Generating Plant (Unit No. 2) [Member]
Variable Interest Entities (Textuals) [Abstract]
Percentage Interest in Rockport Plant Unit 2 Lease		50.00%			50.00%
AEP Generating Co [Member] | Lawrenceburg Generating Station [Member]
Variable Interest Entities (Textuals) [Abstract]
Jointly Owned Utility Plant, Proportionate Ownership Share		100.00%			100.00%
Cleco Power, LLC [Member]
Variable Interest Entities (Textuals) [Abstract]
Percentage of VIE Sales of Lignite Produced					50.00%
First Energy Corp [Member] | Allegheny Series [Member]
Variable Interest Entities (Textuals) [Abstract]
Percentage Ownership of "Allegheny Series" by a Nonaffiliated Company					100.00%
Ohio Power Co [Member]
Related Party Transaction, Due from (to) Related Party, Current		$ 279,129			$ 279,129
Variable Interest Entities (Textuals) [Abstract]
Securitized Transition Assets		91,899			91,899			109,999
Ohio Power Co [Member] | Billings from American Electric Power Service Corporation [Member]
Billings from Affiliates
Billings from VIE		48,471		41,212	128,608		120,696
Variable Interest Entities (Textuals) [Abstract]
Billings from VIE		48,471		$ 41,212	128,608		$ 120,696
Ohio Power Co [Member] | Carrying Amount in AEPSC's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet		18,770			18,770			24,695
Maximum Exposure		18,770			18,770			24,695
Ohio Power Co [Member] | Ohio Phase-In-Recovery Funding [Member]
Variable Interest Entities (Textuals) [Abstract]
Securitization Bonds		187,000			187,000			232,000
Securitized Transition Assets		92,000			92,000			110,000
Ohio Power Co [Member] | Current Assets [Member] | Ohio Phase-In-Recovery Funding [Member]
ASSETS
Assets		20,236			20,236			32,676
Ohio Power Co [Member] | Other Non Current Assets [Member] | Ohio Phase-In-Recovery Funding [Member]
ASSETS
Assets	[5]	175,189			175,189			209,922
Variable Interest Entities (Textuals) [Abstract]
Intercompany Item Eliminated in Consolidation		81,000			81,000			97,000
Ohio Power Co [Member] | Total Assets [Member] | Ohio Phase-In-Recovery Funding [Member]
ASSETS
Assets		195,425			195,425			242,598
Ohio Power Co [Member] | Current Liabilities [Member] | Ohio Phase-In-Recovery Funding [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		46,592			46,592			47,099
Ohio Power Co [Member] | Noncurrent Liabilities [Member] | Ohio Phase-In-Recovery Funding [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		147,496			147,496			194,162
Ohio Power Co [Member] | Equity [Member] | Ohio Phase-In-Recovery Funding [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		1,337			1,337			1,337
Ohio Power Co [Member] | Total Liabilities And Equity [Member] | Ohio Phase-In-Recovery Funding [Member]
LIABILITIES AND EQUITY
Liabilities and Equity		195,425			195,425			242,598
Carrying Amount in AEGCo's Accounts Payable [Member] | Indiana Michigan Power Co [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet		$ 17,000			$ 17,000			$ 20,000

[1] (a)Includes an intercompany item eliminated in consolidation of $70 million

[2] (a)Includes an intercompany item eliminated in consolidation of $75 million

[3] (a)Includes an intercompany item eliminated in consolidation as of September 30, 2015 and December 31, 2014 of $4 million and $4 million, respectively.

[4] (a)Includes affiliate advances due to Parent related to participation in the Utility Money Pool of $40 million and $56 million in 2015 and 2014, respectively.

[5] (a)Includes an intercompany item eliminated in consolidation as of September 30, 2015 and December 31, 2014 of $81 million and $97 million, respectively.