Variable Interest Entities (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended			12 Months Ended
	Jun. 30, 2016		Jun. 30, 2015	Jun. 30, 2016		Jun. 30, 2015	Dec. 31, 2015
Variable Interest Entities (Textuals) [Abstract]
Securitization Bonds	$ 1,837,000			$ 1,837,000			$ 2,024,000
Securitized Transition Assets	1,631,900			$ 1,631,900			1,749,900
Percentage of Ownership of Allegheny Series by a Nonaffiliated Company				100.00%
Protected Cell Of Energy Insurance Services, Inc. [Member]
Variable Interest Entities (Textuals) [Abstract]
Insurance Premium Expense to Protected Cell	147		$ 167	$ 13,000		$ 14,000
Protected Cell Of Energy Insurance Services, Inc. [Member] | Current Assets [Member]
ASSETS
Assets	167,900			167,900			165,300
Protected Cell Of Energy Insurance Services, Inc. [Member] | Net Property Plant And Equipment [Member]
ASSETS
Assets	0			0			0
Protected Cell Of Energy Insurance Services, Inc. [Member] | Other Non Current Assets [Member]
ASSETS
Assets	1,300			1,300			1,900
Protected Cell Of Energy Insurance Services, Inc. [Member] | Total Assets [Member]
ASSETS
Assets	169,200			169,200			167,200
Protected Cell Of Energy Insurance Services, Inc. [Member] | Current Liabilities [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	41,600			41,600			41,800
Protected Cell Of Energy Insurance Services, Inc. [Member] | Noncurrent Liabilities [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	82,600			82,600			83,900
Protected Cell Of Energy Insurance Services, Inc. [Member] | Equity [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	45,000			45,000			41,500
Protected Cell Of Energy Insurance Services, Inc. [Member] | Total Liabilities And Equity [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	169,200			169,200			167,200
Transource Energy [Member]
Variable Interest Entities (Textuals) [Abstract]
Proceeds from Partnership Contribution				26,000			47,000
Transource Energy [Member] | Current Assets [Member]
ASSETS
Assets	15,600			15,600			10,800
Transource Energy [Member] | Net Property Plant And Equipment [Member]
ASSETS
Assets	278,600			278,600			227,200
Transource Energy [Member] | Other Non Current Assets [Member]
ASSETS
Assets	5,700			5,700			5,500
Transource Energy [Member] | Total Assets [Member]
ASSETS
Assets	299,900			299,900			243,500
Transource Energy [Member] | Current Liabilities [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	38,400			38,400			36,600
Transource Energy [Member] | Noncurrent Liabilities [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	125,700			125,700			113,000
Transource Energy [Member] | Equity [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	135,800			135,800			93,900
Transource Energy [Member] | Total Liabilities And Equity [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	299,900			$ 299,900			243,500
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 Credit, Inc. [Member] | Current Assets [Member]
ASSETS
Assets	964,300			$ 964,300			925,700
AEP Credit, Inc. [Member] | Net Property Plant And Equipment [Member]
ASSETS
Assets	0			0			0
AEP Credit, Inc. [Member] | Other Non Current Assets [Member]
ASSETS
Assets	9,600			9,600			6,400
AEP Credit, Inc. [Member] | Total Assets [Member]
ASSETS
Assets	973,900			973,900			932,100
AEP Credit, Inc. [Member] | Current Liabilities [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	873,600			873,600			855,100
AEP Credit, Inc. [Member] | Noncurrent Liabilities [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	500			500			300
AEP Credit, Inc. [Member] | Equity [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	99,800			99,800			76,700
AEP Credit, Inc. [Member] | Total Liabilities And Equity [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	$ 973,900			$ 973,900			932,100
PATH West Virginia Transmission Co, LLC [Member]
Variable Interest Entities (Textuals) [Abstract]
Percentage of Debt Capital Structure in PATH's Stipulation Agreement	50.00%			50.00%
Percentage of Equity Capital Structure in PATH's Stipulation Agreement	50.00%			50.00%
Percentage of Cost of Long Term Debt for PATH's Stipulation Agreement	4.70%			4.70%
PATH West Virginia Transmission Co, LLC [Member] | Capital Contribution From Parent [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet	$ 18,800			$ 18,800			18,800
Maximum Exposure	18,800			18,800			18,800
PATH West Virginia Transmission Co, LLC [Member] | Retained Earnings [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet	2,200			2,200			2,200
Maximum Exposure	2,200			2,200			2,200
PATH West Virginia Transmission Co, LLC [Member] | Total Investment [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
AEP Texas Central Transition Funding Co [Member]
Variable Interest Entities (Textuals) [Abstract]
Securitization Bonds	1,300,000			1,300,000			1,500,000
Securitized Transition Assets	1,200,000			1,200,000			1,300,000
AEP Texas Central Transition Funding Co [Member] | Current Assets [Member]
ASSETS
Assets	177,100			177,100			234,100
AEP Texas Central Transition Funding Co [Member] | Net Property Plant And Equipment [Member]
ASSETS
Assets	0			0			0
AEP Texas Central Transition Funding Co [Member] | Other Non Current Assets [Member]
ASSETS
Assets	1,271,200	[1]		1,271,200	[1]		1,365,700	[2]
Variable Interest Entities (Textuals) [Abstract]
Intercompany Item Eliminated in Consolidation	64,900			64,900			68,200
AEP Texas Central Transition Funding Co [Member] | Total Assets [Member]
ASSETS
Assets	1,448,300			1,448,300			1,599,800
AEP Texas Central Transition Funding Co [Member] | Current Liabilities [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	244,900			244,900			291,700
AEP Texas Central Transition Funding Co [Member] | Noncurrent Liabilities [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	1,185,300			1,185,300			1,290,000
AEP Texas Central Transition Funding Co [Member] | Equity [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	18,100			18,100			18,100
AEP Texas Central Transition Funding Co [Member] | Total Liabilities And Equity [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	$ 1,448,300			$ 1,448,300			1,599,800
Great Plains Energy Inc. [Member] | Transource Energy [Member]
Variable Interest Entities (Textuals) [Abstract]
Equity and Voting Ownership Percentage	13.50%			13.50%
Cleco Power, LLC [Member]
Variable Interest Entities (Textuals) [Abstract]
Percentage of VIE Sales of Lignite Produced				50.00%
Appalachian Power Co [Member]
Variable Interest Entities (Textuals) [Abstract]
Securitized Transition Assets	$ 316,600			$ 316,600			328,000
Appalachian Power Co [Member] | Billings from AEP Service Corporation [Member]
Variable Interest Entities (Textuals) [Abstract]
Billings from VIE	53,900		52,700	110,400		101,000
Appalachian Power Co [Member] | Carrying Amount in AEP Service Corporation's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet	19,500			19,500			25,800
Maximum Exposure	19,500			19,500			25,800
Appalachian Power Co [Member] | Appalachian Consumer Rate Relief Funding [Member]
Variable Interest Entities (Textuals) [Abstract]
Securitization Bonds	331,000			331,000			342,000
Securitized Transition Assets	317,000			317,000			328,000
Appalachian Power Co [Member] | Appalachian Consumer Rate Relief Funding [Member] | Current Assets [Member]
ASSETS
Assets	18,900			18,900			18,500
Appalachian Power Co [Member] | Appalachian Consumer Rate Relief Funding [Member] | Net Property Plant And Equipment [Member]
ASSETS
Assets	0			0			0
Appalachian Power Co [Member] | Appalachian Consumer Rate Relief Funding [Member] | Other Non Current Assets [Member]
ASSETS
Assets	320,500	[3]		320,500	[3]		332,000	[4]
Variable Interest Entities (Textuals) [Abstract]
Intercompany Item Eliminated in Consolidation	3,800			3,800			4,000
Appalachian Power Co [Member] | Appalachian Consumer Rate Relief Funding [Member] | Total Assets [Member]
ASSETS
Assets	339,400			339,400			350,500
Appalachian Power Co [Member] | Appalachian Consumer Rate Relief Funding [Member] | Current Liabilities [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	27,200			27,200			27,100
Appalachian Power Co [Member] | Appalachian Consumer Rate Relief Funding [Member] | Noncurrent Liabilities [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	310,900			310,900			321,500
Appalachian Power Co [Member] | Appalachian Consumer Rate Relief Funding [Member] | Equity [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	1,300			1,300			1,900
Appalachian Power Co [Member] | Appalachian Consumer Rate Relief Funding [Member] | Total Liabilities And Equity [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	339,400			339,400			350,500
Indiana Michigan Power Co [Member] | DCC Fuel [Member]
Variable Interest Entities (Textuals) [Abstract]
Payments Made by I&M to DCC Fuel	25,000		34,000	54,000		57,000
Indiana Michigan Power Co [Member] | DCC Fuel [Member] | Current Assets [Member]
ASSETS
Assets	108,000			108,000			91,100
Indiana Michigan Power Co [Member] | DCC Fuel [Member] | Net Property Plant And Equipment [Member]
ASSETS
Assets	193,800			193,800			159,900
Indiana Michigan Power Co [Member] | DCC Fuel [Member] | Other Non Current Assets [Member]
ASSETS
Assets	103,000			103,000			84,600
Indiana Michigan Power Co [Member] | DCC Fuel [Member] | Total Assets [Member]
ASSETS
Assets	404,800			404,800			335,600
Indiana Michigan Power Co [Member] | DCC Fuel [Member] | Current Liabilities [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	96,200			96,200			84,800
Indiana Michigan Power Co [Member] | DCC Fuel [Member] | Noncurrent Liabilities [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	308,600			308,600			250,800
Indiana Michigan Power Co [Member] | DCC Fuel [Member] | Equity [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	0			0			0
Indiana Michigan Power Co [Member] | DCC Fuel [Member] | Total Liabilities And Equity [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	404,800			404,800			335,600
Indiana Michigan Power Co [Member] | Billings from AEP Service Corporation [Member]
Variable Interest Entities (Textuals) [Abstract]
Billings from VIE	30,100		31,100	65,000		64,600
Indiana Michigan Power Co [Member] | Billings from AEP Generating Company [Member]
Variable Interest Entities (Textuals) [Abstract]
Billings from VIE	56,000		60,000	101,000		115,000
Indiana Michigan Power Co [Member] | Carrying Amount in AEP Service Corporation's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet	11,100			11,100			16,600
Maximum Exposure	11,100			11,100			16,600
Indiana Michigan Power Co [Member] | Carrying Amount in AEP Generating Company's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet	18,000			18,000			17,000
Ohio Power Co [Member]
Variable Interest Entities (Textuals) [Abstract]
Securitized Transition Assets	73,900			73,900			85,900
Ohio Power Co [Member] | Billings from AEP Service Corporation [Member]
Variable Interest Entities (Textuals) [Abstract]
Billings from VIE	39,400		40,900	83,800		80,100
Ohio Power Co [Member] | Carrying Amount in AEP Service Corporation's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet	14,400			14,400			23,300
Maximum Exposure	14,400			14,400			23,300
Ohio Power Co [Member] | Ohio Phase-In-Recovery Funding [Member]
Variable Interest Entities (Textuals) [Abstract]
Securitization Bonds	163,000			163,000			185,000
Securitized Transition Assets	74,000			74,000			86,000
Ohio Power Co [Member] | Ohio Phase-In-Recovery Funding [Member] | Current Assets [Member]
ASSETS
Assets	30,100			30,100			31,200
Ohio Power Co [Member] | Ohio Phase-In-Recovery Funding [Member] | Net Property Plant And Equipment [Member]
ASSETS
Assets	0			0			0
Ohio Power Co [Member] | Ohio Phase-In-Recovery Funding [Member] | Other Non Current Assets [Member]
ASSETS
Assets	139,200	[5]		139,200	[5]		162,000	[6]
Variable Interest Entities (Textuals) [Abstract]
Intercompany Item Eliminated in Consolidation	65,400			65,400			76,100
Ohio Power Co [Member] | Ohio Phase-In-Recovery Funding [Member] | Total Assets [Member]
ASSETS
Assets	169,300			169,300			193,200
Ohio Power Co [Member] | Ohio Phase-In-Recovery Funding [Member] | Current Liabilities [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	46,900			46,900			47,300
Ohio Power Co [Member] | Ohio Phase-In-Recovery Funding [Member] | Noncurrent Liabilities [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	121,100			121,100			144,600
Ohio Power Co [Member] | Ohio Phase-In-Recovery Funding [Member] | Equity [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	1,300			1,300			1,300
Ohio Power Co [Member] | Ohio Phase-In-Recovery Funding [Member] | Total Liabilities And Equity [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	169,300			169,300			193,200
Public Service Co Of Oklahoma [Member] | Billings from AEP Service Corporation [Member]
Variable Interest Entities (Textuals) [Abstract]
Billings from VIE	25,000		24,400	53,500		48,000
Public Service Co Of Oklahoma [Member] | Carrying Amount in AEP Service Corporation's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet	9,000			9,000			12,600
Maximum Exposure	9,000			9,000			12,600
Southwestern Electric Power Co [Member] | Sabine Mining Co [Member]
Variable Interest Entities (Textuals) [Abstract]
Billings from VIE	44,000		41,000	85,000		83,000
Southwestern Electric Power Co [Member] | Sabine Mining Co [Member] | Current Assets [Member]
ASSETS
Assets	59,900			59,900			61,700
Southwestern Electric Power Co [Member] | Sabine Mining Co [Member] | Net Property Plant And Equipment [Member]
ASSETS
Assets	136,900			136,900			147,000
Southwestern Electric Power Co [Member] | Sabine Mining Co [Member] | Other Non Current Assets [Member]
ASSETS
Assets	63,500			63,500			61,800
Southwestern Electric Power Co [Member] | Sabine Mining Co [Member] | Total Assets [Member]
ASSETS
Assets	260,300			260,300			270,500
Southwestern Electric Power Co [Member] | Sabine Mining Co [Member] | Current Liabilities [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	34,900			34,900			47,700
Southwestern Electric Power Co [Member] | Sabine Mining Co [Member] | Noncurrent Liabilities [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	225,000			225,000			222,300
Southwestern Electric Power Co [Member] | Sabine Mining Co [Member] | Equity [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	400			400			500
Southwestern Electric Power Co [Member] | Sabine Mining Co [Member] | Total Liabilities And Equity [Member]
LIABILITIES AND EQUITY
Liabilities and Equity	260,300			260,300			270,500
Southwestern Electric Power Co [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	17,500			17,500			15,300
Maximum Exposure	104,000			104,000			98,200
Variable Interest Entities (Textuals) [Abstract]
Billings from VIE	13,000		15,000	$ 28,000		29,000
Percentage of VIE Sales of Lignite Produced				50.00%
Percentage of DHLCs Debt Guaranteed by Each SWEPCo and CLECO				50.00%
Percentage Of Management Fee Received by SWEPCo from DHLC				100.00%
Southwestern Electric Power Co [Member] | Dolet Hills Lignite Co, LLC [Member] | Capital Contribution From Parent [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet	7,600			$ 7,600			7,600
Maximum Exposure	7,600			7,600			7,600
Southwestern Electric Power Co [Member] | Dolet Hills Lignite Co, LLC [Member] | Retained Earnings [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet	9,900			9,900			7,700
Maximum Exposure	9,900			9,900			7,700
Southwestern Electric Power Co [Member] | Dolet Hills Lignite Co, LLC [Member] | SWEPCo's Guarantee Of Debt [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	86,500			86,500			82,900
Southwestern Electric Power Co [Member] | Billings from AEP Service Corporation [Member]
Variable Interest Entities (Textuals) [Abstract]
Billings from VIE	33,000		$ 31,900	69,800		$ 63,400
Southwestern Electric Power Co [Member] | Carrying Amount in AEP Service Corporation's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]
As Reported on the Consolidated Balance Sheet	12,500			12,500			16,400
Maximum Exposure	$ 12,500			$ 12,500			$ 16,400
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%
Transource Energy [Member]
Variable Interest Entities (Textuals) [Abstract]
Equity and Voting Ownership Percentage	86.50%			86.50%

[1] Includes an intercompany item eliminated in consolidation of $64.9 million.

[2] Includes an intercompany item eliminated in consolidation of $68.2 million.

[3] Includes an intercompany item eliminated in consolidation of $3.8 million.

[4] Includes an intercompany item eliminated in consolidation of $4.0 million.

[5] Includes an intercompany item eliminated in consolidation of $65.4 million.

[6] Includes an intercompany item eliminated in consolidation of $76.1 million.