Fair Value Long-term Debt, Other Temporary Investments, Nuclear Trusts (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		$ 19,426,000		$ 19,426,000		$ 18,601,000
Long Term Debt, Fair Value		21,257,000		21,257,000		21,075,000
Other Temporary Investments
Cost		305,000		305,000		374,000
Gross Unrealized Gains		10,000		10,000		12,000
Gross Unrealized Losses		0		0		0
Fair Value		315,000		315,000		386,000
Debt and Equity Securities Within Other Temporary Investments [Abstract]
Proceeds from Investment Sales		0	$ 0	0	$ 0
Purchases of Investments		10,000	0	10,000	1,000
Gross Realized Gains on Investment Sales		0	0	0	0
Gross Realized Losses on Investment Sales		0	0	0	0
Nuclear Trust Fund Investments [Abstract]
Fair Value		2,047,000		2,047,000		2,096,000
Gross Unrealized Gains		566,000		566,000		649,000
Other-Than-Temporary Impairments		(83,000)		(83,000)		(85,000)
Securities Activity Within Decommissioning and SNF Trusts [Abstract]
Proceeds from Investment Sales		921,000	263,000	1,437,000	746,000
Purchases of Investments		938,000	281,000	1,479,000	790,000
Gross Realized Gains on Investment Sales		15,000	8,000	34,000	25,000
Gross Realized Losses on Investment Sales		13,000	1,000	23,000	10,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		2,047,000		2,047,000		2,096,000
Fair Value Measurements (Textuals) [Abstract]
Adjusted Cost of Debt Securities		766,000		766,000		903,000
Adjusted Cost of Domestic Equity Securities		551,000		551,000		524,000
Includes Debt Included In Liabilities Held For Sale [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding	[1],[2]	19,507,000		19,507,000		18,684,000
Appalachian Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		3,955,295		3,955,295		3,980,274
Long Term Debt, Fair Value		4,460,140		4,460,140		4,711,210
Indiana Michigan Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		2,060,651		2,060,651		2,027,397
Long Term Debt, Fair Value		2,241,930		2,241,930		2,255,124
Nuclear Trust Fund Investments [Abstract]
Fair Value		2,047,260		2,047,260		2,095,732
Gross Unrealized Gains		565,889		565,889		649,132
Other-Than-Temporary Impairments		(83,938)		(83,938)		(85,495)
Securities Activity Within Decommissioning and SNF Trusts [Abstract]
Proceeds from Investment Sales		921,552	263,738	1,437,336	746,272
Purchases of Investments		938,438	280,626	1,479,149	789,461
Gross Realized Gains on Investment Sales		15,030	7,617	33,840	24,835
Gross Realized Losses on Investment Sales		13,167	$ 1,739	22,823	$ 10,447
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		2,047,260		2,047,260		2,095,732
Fair Value Measurements (Textuals) [Abstract]
Adjusted Cost of Debt Securities		766,000		766,000		903,000
Adjusted Cost of Domestic Equity Securities		551,000		551,000		524,000
Ohio Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		2,166,050		2,166,050		2,297,123
Long Term Debt, Fair Value		2,502,105		2,502,105		2,709,452
Public Service Co Of Oklahoma [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		1,290,973		1,290,973		1,041,036
Long Term Debt, Fair Value		1,424,300		1,424,300		1,216,205
Southwestern Electric Power Co [Member]
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding		2,283,966		2,283,966		2,140,437
Long Term Debt, Fair Value		2,446,716		2,446,716		2,402,639
Cash [Member]
Other Temporary Investments
Cost	[3]	201,000		201,000		280,000
Gross Unrealized Gains	[3]	0		0		0
Gross Unrealized Losses	[3]	0		0		0
Fair Value	[3],[4]	201,000		201,000		280,000
Nuclear Trust Fund Investments [Abstract]
Fair Value	[5]	164,000		164,000		20,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	[5]	164,000		164,000		20,000
Cash [Member] | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value	[6]	164,353		164,353		19,966
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	[6]	164,353		164,353		19,966
Fixed Income Funds [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		816,000		816,000		953,000
Gross Unrealized Gains		50,000		50,000		50,000
Other-Than-Temporary Impairments		(3,000)		(3,000)		(6,000)
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		816,000		816,000		953,000
Fixed Income Funds [Member] | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		816,480		816,480		953,387
Gross Unrealized Gains		49,683		49,683		50,344
Other-Than-Temporary Impairments		(3,658)		(3,658)		(6,353)
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		816,480		816,480		953,387
Mutual Funds Fixed Income [Member]
Other Temporary Investments
Cost		90,000		90,000		81,000
Gross Unrealized Gains		0		0		0
Gross Unrealized Losses		0		0		0
Fair Value		90,000		90,000		81,000
Domestic [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value	[7]	1,067,000		1,067,000		1,123,000
Gross Unrealized Gains		516,000		516,000		599,000
Other-Than-Temporary Impairments		(80,000)		(80,000)		(79,000)
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	[7]	1,067,000		1,067,000		1,123,000
Domestic [Member] | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value	[8]	1,066,427		1,066,427		1,122,379
Gross Unrealized Gains		516,206		516,206		598,788
Other-Than-Temporary Impairments		(80,280)		(80,280)		(79,142)
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	[8]	1,066,427		1,066,427		1,122,379
Mutual Funds Equity [Member]
Other Temporary Investments
Cost		14,000		14,000		13,000
Gross Unrealized Gains		10,000		10,000		12,000
Gross Unrealized Losses		0		0		0
Fair Value	[7]	24,000		24,000		25,000
Cash and Cash Equivalents [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		164,000		164,000		20,000
Gross Unrealized Gains		0		0		0
Other-Than-Temporary Impairments		0		0		0
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		164,000		164,000		20,000
Cash and Cash Equivalents [Member] | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		164,353		164,353		19,966
Gross Unrealized Gains		0		0		0
Other-Than-Temporary Impairments		0		0		0
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		164,353		164,353		19,966
US Government Agencies Debt Securities [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		704,000		704,000		697,000
Gross Unrealized Gains		45,000		45,000		45,000
Other-Than-Temporary Impairments		(2,000)		(2,000)		(5,000)
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		704,000		704,000		697,000
US Government Agencies Debt Securities [Member] | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		704,344		704,344		697,042
Gross Unrealized Gains		45,005		45,005		44,615
Other-Than-Temporary Impairments		(2,291)		(2,291)		(5,016)
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		704,344		704,344		697,042
Corporate Debt [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		62,000		62,000		48,000
Gross Unrealized Gains		4,000		4,000		4,000
Other-Than-Temporary Impairments		(1,000)		(1,000)		(1,000)
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		62,000		62,000		48,000
Corporate Debt [Member] | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		62,118		62,118		47,792
Gross Unrealized Gains		3,682		3,682		4,523
Other-Than-Temporary Impairments		(1,043)		(1,043)		(1,018)
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		62,118		62,118		47,792
State and Local Jurisdiction [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		50,000		50,000		208,000
Gross Unrealized Gains		1,000		1,000		1,000
Other-Than-Temporary Impairments		0		0		0
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		50,000		50,000		208,000
State and Local Jurisdiction [Member] | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		50,018		50,018		208,553
Gross Unrealized Gains		996		996		1,206
Other-Than-Temporary Impairments		(324)		(324)		(319)
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		50,018		50,018		$ 208,553
Within One Year [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		166,000		166,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		166,000		166,000
Within One Year [Member] | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		166,336		166,336
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		166,336		166,336
One Year To Five Year [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		336,000		336,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		336,000		336,000
One Year To Five Year [Member] | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		335,823		335,823
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		335,823		335,823
Five Year To Ten Year [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		140,000		140,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		140,000		140,000
Five Year To Ten Year [Member] | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		140,129		140,129
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		140,129		140,129
After Ten Year [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		174,000		174,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		174,000		174,000
After Ten Year [Member] | Indiana Michigan Power Co [Member]
Nuclear Trust Fund Investments [Abstract]
Fair Value		174,192		174,192
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities		$ 174,192		$ 174,192

[1] Amounts include debt related to AEPRO that have been classified as Liabilities Held for Sale on the condensed balance sheets. See "AEPRO (AEP River Operations Segment)" section of Note 6 for additional information.

[2] Amounts include debt related to AEPRO that have been classified as Liabilities Held for Sale on the condensed balance sheets. See "AEPRO (AEP River Operations Segment)" section of Note 6 for additional information.

[3] Primarily represents amounts held for the repayment of debt.

[4] Amounts in ''Other'' column primarily represent cash deposits in bank accounts with financial institutions or with third parties. Level 1 and Level 2 amounts primarily represent investments in money market funds.

[5] Amounts in ''Other'' column primarily represent accrued interest receivables from financial institutions. Level 1 amounts primarily represent investments in money market funds.

[6] Amounts in “Other” column primarily represent accrued interest receivables from financial institutions. Level 1 amounts primarily represent investments in money market funds.

[7] Amounts represent publicly traded equity securities and equity-based mutual funds.

[8] Amounts represent publicly traded equity securities and equity-based mutual funds.