Significant Accounting Matters (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Columbus Southern Power Co [Member]
Basic and Diluted EPS Calculations
Net Income (Loss) Available to Common Stockholders, Basic, Total	$ 66,503	$ 52,076	$ 132,036	$ 103,687
Amounts Attributable To AEP Common Shareholders
Net Income	66,503	52,076	132,036	103,687
Ohio Power Co [Member]
Basic and Diluted EPS Calculations
Net Income (Loss) Available to Common Stockholders, Basic, Total	75,483	37,365	175,712	129,085
Amounts Attributable To AEP Common Shareholders
Net Income	75,483	37,365	175,712	129,085
Southwestern Electric Power Co [Member]
Basic and Diluted EPS Calculations
Net Income (Loss) Available to Common Stockholders, Basic, Total	49,978	25,375	78,666	55,250
Amounts Attributable To AEP Common Shareholders
Net Income	49,978	25,375	78,666	55,250
Indiana Michigan Power Co [Member]
Basic and Diluted EPS Calculations
Net Income (Loss) Available to Common Stockholders, Basic, Total	31,301	14,517	76,643	59,490
Amounts Attributable To AEP Common Shareholders
Net Income	$ 31,301	$ 14,517	$ 76,643	$ 59,490