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Effects of Regulation (Details) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Regulatory Assets    
Current Regulatory Assets $ 65,000 $ 81,000
Noncurrent Regulatory Assets 6,026,000 4,943,000
Regulatory Liabilities    
Current Regulatory Liabilities 8,000 17,000
Noncurrent Regulatory Liabilities 3,195,000 3,171,000
Appalachian Power Co [Member]
    
Regulatory Assets    
Current Regulatory Assets 41,105 18,300
Noncurrent Regulatory Assets 1,481,193 1,486,625
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 576,792 562,381
Southwestern Electric Power Co [Member]
    
Regulatory Assets    
Current Regulatory Assets 10,843 758
Noncurrent Regulatory Assets 394,276 332,698
Regulatory Liabilities    
Current Regulatory Liabilities 5,032 16,432
Noncurrent Regulatory Liabilities 428,571 393,673
Ohio Power Co [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 1,370,504 1,232,122
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 301,124 290,291
Public Service Co Of Oklahoma [Member]
    
Regulatory Assets    
Current Regulatory Assets 4,313 37,262
Noncurrent Regulatory Assets 266,545 263,545
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 334,812 336,961
Indiana Michigan Power Co [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 602,979 556,254
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 875,202 852,197
Regulatory Liabilities Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 3,129,000 3,130,000
Regulatory Liabilities Not Yet Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 66,000 41,000
Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 5,871,000 4,548,000
Regulatory Assets Not Yet Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 155,000 395,000
Deferred Fuel Costs [Member] | Regulatory Assets Currently Earning a Return [Member]
    
Regulatory Assets    
Current Regulatory Assets 56,000 73,000
Remaining Recovery Period, Current 1  
Deferred Fuel Costs [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 521,000 476,000
Remaining Recovery Period, Noncurrent 7  
Deferred Fuel Costs [Member] | Regulatory Assets Currently Not Earning a Return [Member]
    
Regulatory Assets    
Current Regulatory Assets 9,000 8,000
Remaining Recovery Period, Current 1  
Customer Choice Deferrals [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Not Yet Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 0 59,000
Storm Costs [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 65,000 38,000
Remaining Recovery Period, Noncurrent 7  
Storm Costs [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Not Yet Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 24,000 55,000
Storm Costs [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 35,000 21,000
Remaining Recovery Period, Noncurrent 7  
Storm Costs [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Not Yet Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 10,000 45,000
Line Extension Carrying Costs [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Not Yet Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 0 55,000
Acquisition of Monongahela Power [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Not Yet Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 0 8,000
Acquisition of Monongahela Power [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Not Yet Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 0 4,000
Product Validation Facility [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Not Yet Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 14,000 60,000
Deferred Wind Power Costs [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Not Yet Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 38,000 29,000
Transmission Rate Adjustment Clause [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 20,000 19,000
Remaining Recovery Period, Noncurrent 2  
Environmental Rate Adjustment Clause [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 24,000 0
Remaining Recovery Period, Noncurrent 2  
Environmental Rate Adjustment Clause [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Not Yet Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 18,000 56,000
Special Rate Mechanism for Century Aluminum [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Not Yet Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 13,000 13,000
Unrealized Loss on Forward Commitments [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 16,000 10,000
Remaining Recovery Period, Noncurrent 2  
Unamortized Loss on Reacquired Debt [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 92,000 93,000
Remaining Recovery Period, Noncurrent 32  
Economic Development Rider [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 12,000 1,000
Remaining Recovery Period, Noncurrent 1  
Economic Development Rider [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Not Yet Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 13,000 6,000
Red Rock Generating Facility [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 10,000 10,000
Remaining Recovery Period, Noncurrent 45  
Deferred Income Tax Charges [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 1,237,000 1,097,000
Remaining Recovery Period, Noncurrent 37  
Expanded Net Energy Charge [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 327,000 361,000
Remaining Recovery Period, Noncurrent 2  
Expanded Net Energy Charge [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 32,000 0
Remaining Recovery Period, Noncurrent 6  
Restructuring Transition Costs [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 8,000 14,000
Remaining Recovery Period, Noncurrent 5  
Postemployment Benefits [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 47,000 51,000
Remaining Recovery Period, Noncurrent 4  
Cook Nuclear Plant Refueling Outage Levelization [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 41,000 54,000
Remaining Recovery Period, Noncurrent 2  
Offsystem Sales Margin Sharing [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 0 13,000
Vegetation Management [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 11,000 13,000
Remaining Recovery Period, Noncurrent 1  
Asset Retirement Obligation Costs [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 14,000 15,000
Remaining Recovery Period, Noncurrent 9  
Other Regulatory Assets Not Yet Being Recovered [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Not Yet Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 0 1,000
Other Regulatory Assets Not Yet Being Recovered [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Not Yet Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 14,000 4,000
Other Regulatory Assets Being Recovered [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 15,000 17,000
Other Regulatory Assets Being Recovered [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 46,000 46,000
Transmission Cost Recovery Rider [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 28,000 0
Remaining Recovery Period, Noncurrent 2  
Regional Transmission Organization Formation/Integration Costs [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 18,000 21,000
Remaining Recovery Period, Noncurrent 8  
Capacity Auction True-Up [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 692,000 0
Remaining Recovery Period, Noncurrent 13  
Litigation Settlement [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Not Yet Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 11,000 0
Deferred Restructuring Costs [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 18,000 6,000
Remaining Recovery Period, Noncurrent 7  
Deferred PJM Fees [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 22,000 7,000
Remaining Recovery Period, Noncurrent 1  
Distribution Asset Recovery Rider [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 173,000 0
Remaining Recovery Period, Noncurrent 7  
Meter Replacement Costs [Member] | Regulatory Assets Currently Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 39,000 4,000
Remaining Recovery Period, Noncurrent 29  
Other Postretirement Benefit Plans [Member] | Pension Costs [Member] | Regulatory Assets Currently Not Earning a Return [Member] | Regulatory Assets Being Recovered [Member]
    
Regulatory Assets    
Noncurrent Regulatory Assets 2,308,000 2,161,000
Remaining Recovery Period, Noncurrent 13  
Regulatory Liabilities Currently Paying a Return [Member] | Deferred Fuel Costs [Member]
    
Regulatory Liabilities    
Current Regulatory Liabilities 5,000 16,000
Remaining Refund Period, Current 1  
Regulatory Liabilities Currently Paying a Return [Member] | Asset Removal Costs [Member] | Regulatory Liabilities Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 2,270,000 [1] 2,222,000 [1]
Regulatory Liabilities Currently Paying a Return [Member] | Deferred Investment Tax Credits [Member] | Regulatory Liabilities Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 27,000 32,000
Remaining Refund Period, Noncurrent 11  
Regulatory Liabilities Currently Paying a Return [Member] | Advanced Metering Infrastructure Surcharge [Member] | Regulatory Liabilities Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 78,000 61,000
Remaining Refund Period, Noncurrent 9  
Regulatory Liabilities Currently Paying a Return [Member] | Excess Earnings [Member] | Regulatory Liabilities Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 13,000 13,000
Remaining Refund Period, Noncurrent 42  
Regulatory Liabilities Currently Paying a Return [Member] | Other Regulatory Liabilities Not Yet Being Paid [Member] | Regulatory Liabilities Not Yet Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 5,000 0
Regulatory Liabilities Currently Paying a Return [Member] | Other Regulatory Liabilities Being Paid [Member] | Regulatory Liabilities Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 4,000 4,000
Regulatory Liabilities Currently Paying a Return [Member] | Refundable Construction Financing Costs [Member] | Regulatory Liabilities Not Yet Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 53,000 20,000
Regulatory Liabilities Currently Not Paying a Return [Member] | Deferred Fuel Costs [Member]
    
Regulatory Liabilities    
Current Regulatory Liabilities 3,000 1,000
Remaining Refund Period, Current 1  
Regulatory Liabilities Currently Not Paying a Return [Member] | Deferred Investment Tax Credits [Member] | Regulatory Liabilities Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 144,000 242,000
Remaining Refund Period, Noncurrent 75  
Regulatory Liabilities Currently Not Paying a Return [Member] | Excess Asset Retirement Obligations For Nuclear Decommissioning Liability [Member] | Regulatory Liabilities Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 377,000 [2] 354,000 [2]
Regulatory Liabilities Currently Not Paying a Return [Member] | Unrealized Gain on Forward Commitments [Member] | Regulatory Liabilities Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 41,000 60,000
Remaining Refund Period, Noncurrent 5  
Regulatory Liabilities Currently Not Paying a Return [Member] | Spent Nuclear Fuel Liability [Member] | Regulatory Liabilities Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 43,000 [2] 42,000 [2]
Regulatory Liabilities Currently Not Paying a Return [Member] | Competitive Transition Charge [Member] | Regulatory Liabilities Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 41,000 38,000
Remaining Refund Period, Noncurrent 10  
Regulatory Liabilities Currently Not Paying a Return [Member] | Deferred State Income Tax Coal Credits [Member] | Regulatory Liabilities Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 29,000 29,000
Remaining Refund Period, Noncurrent 10  
Regulatory Liabilities Currently Not Paying a Return [Member] | Overrecovery Of Pjm Expenses [Member] | Regulatory Liabilities Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 0 12,000
Regulatory Liabilities Currently Not Paying a Return [Member] | Other Regulatory Liabilities Not Yet Being Paid [Member] | Regulatory Liabilities Not Yet Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 4,000 11,000
Regulatory Liabilities Currently Not Paying a Return [Member] | Other Regulatory Liabilities Being Paid [Member] | Regulatory Liabilities Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 22,000 11,000
Regulatory Liabilities Currently Not Paying a Return [Member] | GridSMART Costs [Member] | Regulatory Liabilities Not Yet Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities 4,000 10,000
Regulatory Liabilities Currently Not Paying a Return [Member] | Energy Efficiency/Peak Demand Reduction [Member] | Regulatory Liabilities Being Paid [Member]
    
Regulatory Liabilities    
Noncurrent Regulatory Liabilities $ 40,000 $ 10,000
Remaining Refund Period, Noncurrent 1  
[1] Relieved as removal costs are incurred.
[2] Relieved when plant is decommissioned.