Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Appalachian Power Co [Member]	Indiana Michigan Power Co [Member]	Ohio Power Co [Member]	Public Service Co Of Oklahoma [Member]	Southwestern Electric Power Co [Member]	Common Stock [Member]	Common Stock [Member] Appalachian Power Co [Member]	Common Stock [Member] Indiana Michigan Power Co [Member]	Common Stock [Member] Ohio Power Co [Member]	Common Stock [Member] Public Service Co Of Oklahoma [Member]	Common Stock [Member] Southwestern Electric Power Co [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Appalachian Power Co [Member]	Additional Paid-in Capital [Member] Indiana Michigan Power Co [Member]	Additional Paid-in Capital [Member] Ohio Power Co [Member]	Additional Paid-in Capital [Member] Public Service Co Of Oklahoma [Member]	Additional Paid-in Capital [Member] Southwestern Electric Power Co [Member]	Retained Earnings [Member]	Retained Earnings [Member] Appalachian Power Co [Member]	Retained Earnings [Member] Indiana Michigan Power Co [Member]	Retained Earnings [Member] Ohio Power Co [Member]	Retained Earnings [Member] Public Service Co Of Oklahoma [Member]	Retained Earnings [Member] Southwestern Electric Power Co [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Other Comprehensive Income [Member] Appalachian Power Co [Member]	Accumulated Other Comprehensive Income [Member] Indiana Michigan Power Co [Member]	Accumulated Other Comprehensive Income [Member] Ohio Power Co [Member]	Accumulated Other Comprehensive Income [Member] Public Service Co Of Oklahoma [Member]	Accumulated Other Comprehensive Income [Member] Southwestern Electric Power Co [Member]	Noncontrolling Interests [Member]	Noncontrolling Interests [Member] Southwestern Electric Power Co [Member]
Beginning Balance at Dec. 31, 2013	$ 16,086,000	$ 3,229,432	$ 1,922,153	$ 1,625,265	$ 942,101	$ 2,055,917	$ 3,303,000	$ 260,458	$ 56,584	$ 321,201	$ 157,230	$ 135,660	$ 6,131,000	$ 1,809,562	$ 980,896	$ 663,782	$ 364,037	$ 674,606	$ 6,766,000	$ 1,156,461	$ 900,182	$ 633,203	$ 415,076	$ 1,253,617	$ (115,000)	$ 2,951	$ (15,509)	$ 7,079	$ 5,758	$ (8,444)	$ 1,000	$ 478
Beginning Balance, Shares at Dec. 31, 2013							508,000,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock, Value	63,000						$ 9,000						54,000
Issuance of Common Stock, Shares							2,000,000
Common Stock Dividends	(736,000)																		(733,000)												(3,000)
Common Stock Dividends		(60,000)	(100,000)	(35,000)		(75,000)														(60,000)	(100,000)	(35,000)		(75,000)
Common Stock Dividends						(3,483)																										(3,483)
Other Changes in Equity	3,000												6,000						(6,000)												3,000
Net Income (Loss)																			1,443,000					126,995
Net Income (Loss) Attributable to Noncontrolling Interests	3,000					3,337																									3,000	3,337
Net Income (Loss)	1,446,000	186,856	141,049	171,369	75,983	130,332														186,856	141,049	171,369	75,983
Other Comprehensive Income (Loss)	10,000	(417)	1,313	(1,134)	(626)	932																			10,000	(417)	1,313	(1,134)	(626)	932
Contribution of Mutual Energy SWEPCo, LLC from Parent						0
Ending Balance at Sep. 30, 2014	16,872,000	3,355,871	1,964,515	1,760,500	1,017,458	2,108,698	$ 3,312,000	260,458	56,584	321,201	157,230	135,660	6,191,000	1,809,562	980,896	663,782	364,037	674,606	7,470,000	1,283,317	941,231	769,572	491,059	1,305,612	(105,000)	2,534	(14,196)	5,945	5,132	(7,512)	4,000	332
Ending Balance, Shares at Sep. 30, 2014							510,000,000
Beginning Balance at Dec. 31, 2014	$ 16,824,000	3,366,928	1,953,949	1,980,210	$ 1,028,215	2,097,201	$ 3,313,000	260,458	56,584	321,201	157,230	135,660	6,204,000	1,809,562	980,896	838,782	364,037	674,606	7,406,000	1,291,876	930,829	814,625	502,005	1,293,986	(103,000)	5,032	(14,360)	5,602	4,943	(7,466)	4,000	415
Beginning Balance, Shares at Dec. 31, 2014	509,739,159				10,482,000		510,000,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock, Value	$ 68,000						$ 9,000						59,000
Issuance of Common Stock, Shares							1,000,000
Common Stock Dividends	(783,000)																		(780,000)												(3,000)
Common Stock Dividends		(181,250)	(90,000)	(156,250)		(90,000)														(181,250)	(90,000)	(156,250)		(90,000)
Common Stock Dividends						(3,099)																										(3,099)
Other Changes in Equity	24,000												19,000																		5,000
Net Income (Loss)																			1,578,000					185,287
Net Income (Loss) Attributable to Noncontrolling Interests	4,000					3,002																									4,000	3,002
Net Income (Loss)	1,582,000	275,441	179,907	184,688	$ 85,522	188,289														275,441	179,907	184,688	85,522
Other Comprehensive Income (Loss)	(11,000)	(1,465)	835	(1,030)	(569)	847																			(11,000)	(1,465)	835	(1,030)	(569)	847
Contribution of Mutual Energy SWEPCo, LLC from Parent						1,945												1,945
Ending Balance at Sep. 30, 2015	$ 17,709,000	$ 3,459,654	$ 2,044,691	$ 2,007,618	$ 1,113,168	$ 2,195,183	$ 3,322,000	$ 260,458	$ 56,584	$ 321,201	$ 157,230	$ 135,660	$ 6,282,000	$ 1,809,562	$ 980,896	$ 838,782	$ 364,037	$ 676,551	$ 8,204,000	$ 1,386,067	$ 1,020,736	$ 843,063	$ 587,527	$ 1,389,273	(109,000)	$ 3,567	$ (13,525)	$ 4,572	$ 4,374	$ (6,619)	$ 10,000	$ 318
Ending Balance, Shares at Sep. 30, 2015	511,141,256				10,482,000		511,000,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Pension and OPEB Adjustment Related to Mitchell Plant	$ 5,000																								$ 5,000