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Organization and Summary of Significant Accounting Policies (Details)
$ / shares in Units, $ in Millions
3 Months Ended 12 Months Ended 63 Months Ended 90 Months Ended
Dec. 31, 2018
USD ($)
$ / shares
Sep. 30, 2018
USD ($)
$ / shares
Jun. 30, 2018
USD ($)
$ / shares
Mar. 31, 2018
USD ($)
$ / shares
Dec. 31, 2017
USD ($)
$ / shares
Sep. 30, 2017
USD ($)
$ / shares
Jun. 30, 2017
USD ($)
$ / shares
Mar. 31, 2017
USD ($)
$ / shares
Dec. 31, 2018
USD ($)
$ / shares
shares
Dec. 31, 2017
USD ($)
$ / shares
shares
Dec. 31, 2016
USD ($)
$ / shares
shares
Mar. 31, 2018
Jun. 30, 2018
Dec. 31, 2015
USD ($)
Cash, Cash Equivalents and Restricted Cash                            
Cash and Cash Equivalents at Beginning of Period       $ 214.6         $ 214.6          
Supplemental Income Statement Elements                            
Depreciation and Amortization of Property, Plant and Equipment                 1,965.0 $ 1,709.1 $ 1,688.5      
Amortization of Certain Securitized Assets                 287.9 275.9 254.6      
Amortization of Regulatory Assets and Liabilities                 33.7 12.2 19.2      
Utilities Operating Expense, Depreciation and Amortization                 2,286.6 1,997.2 1,962.3      
Cash Paid (Received) for:                            
Cash Paid for Interest, Net of Capitalized Amounts                 939.3 858.3 848.5      
Income Taxes Paid, Net                 (24.7) (1.1) 29.5      
Construction in Progress Expenditures Incurred but Not yet Paid                 1,120.4 1,330.8 858.0      
Noncash Investing and Financing Activities:                            
Capital Lease Obligations Incurred                 55.6 60.7 86.1      
Construction Expenditures Included in Current Liabilities as of December 31,                 1,120.4 1,330.8 858.0      
Construction Expenditures Included in Noncurrent Liabilities as of December 31,                 0.0 71.8 0.0      
Acquisition of Nuclear Fuel Included in Current Liabilities as of December 31,                 4.0 0.0 2.1      
Noncash Contribution of Assets by Noncontrolling Interest                 84.0 0.0 0.0      
Expected Reimbursement For Spent Nuclear Fuel Dry Cask Storage                 2.2 2.6 0.7      
Restricted Cash $ 210.0       $ 198.0       210.0 198.0        
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations $ 444.1       $ 412.6       444.1 412.6 403.5     $ 426.9
Amounts Attributable to AEP Common Shareholders                            
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest                 1,931.3 1,928.9 620.5      
Net Income (Loss) Attributable to Noncontrolling Interests                 7.5 16.3 7.1      
Net Income (Loss) from Continuing Operations Available to Common Shareholders, Basic                 $ 1,923.8 $ 1,912.6 $ 613.4      
Weighted Average Number of Basic AEP Common Shares Outstanding | shares                 492,774,600 491,814,651 491,495,458      
BASIC EARNINGS PER SHARE ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS FROM CONTINUING OPERATIONS | $ / shares $ 0.74 [1] $ 1.17 [1] $ 1.07 [1] $ 0.92 [1] $ 0.81 [1] $ 1.11 [1] $ 0.76 [1] $ 1.20 [1] $ 3.90 $ 3.89 $ 1.25      
Weighted Average Dilutive Effect of:                            
Weighted Average Number of Diluted AEP Common Shares Outstanding | shares                 493,758,277 492,611,067 491,662,007      
DILUTED EARNINGS PER SHARE ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS FROM CONTINUING OPERATIONS | $ / shares $ 0.74 [1] $ 1.17 [1] $ 1.07 [1] $ 0.92 [1] $ 0.81 [1] $ 1.10 [1] $ 0.76 [1] $ 1.20 [1] $ 3.90 $ 3.88 $ 1.25      
Revenues                            
TOTAL REVENUES $ 3,801.1 $ 4,333.1 $ 4,013.2 $ 4,048.3 $ 3,810.4 $ 4,104.7 $ 3,576.5 $ 3,933.3 $ 16,195.7 $ 15,424.9 $ 16,380.1      
Expenses                            
Depreciation and Amortization                 2,286.6 1,997.2 1,962.3      
TOTAL EXPENSES                 13,513.0 11,899.9 15,216.2      
OPERATING INCOME (LOSS) 551.1 668.6 757.0 706.0 730.9 [2] 975.1 [2] 733.3 [2] 1,085.7 [2] 2,682.7 3,525.0 1,163.9      
Other Income (Expense)                            
Allowance for Equity Funds Used During Construction                 132.5 93.7 113.2      
Interest Expense                 (984.4) (895.0) (877.2)      
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) AND EQUITY EARNINGS (LOSS)                 1,973.5 2,816.2 475.6      
Income Tax Expense (Benefit)                 115.3 969.7 (73.7)      
NET INCOME (LOSS) 364.8 579.7 530.1 456.7 401.8 556.7 376.2 594.2 1,931.3 1,928.9 618.0      
Accounts Receivable:                            
Customers 699.0       643.9       699.0 643.9        
Total Accounts Receivable 1,926.5       1,891.0       1,926.5 1,891.0        
TOTAL CURRENT ASSETS 4,113.9       4,253.1       4,113.9 4,253.1        
Property, Plant and Equipment                            
Transmission 21,531.0       18,972.5       21,531.0 18,972.5        
Other Property, Plant and Equipment 4,265.0       3,706.3       4,265.0 3,706.3        
Construction Work in Progress 4,393.9       4,120.7       4,393.9 4,120.7        
Total Property, Plant and Equipment 73,085.2       67,428.5       73,085.2 67,428.5        
Accumulated Depreciation and Amortization 17,986.1       17,167.0       17,986.1 17,167.0        
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET 55,099.1       50,261.5       55,099.1 50,261.5        
Other Noncurrent Assets                            
TOTAL OTHER NONCURRENT ASSETS 9,589.8       10,214.5       9,589.8 10,214.5        
TOTAL ASSETS 68,802.8       64,729.1       68,802.8 64,729.1 63,467.7      
Current Liabilities                            
Accounts Payable 1,874.3       2,065.3       1,874.3 2,065.3        
Accrued Taxes 1,218.0       1,115.5       1,218.0 1,115.5        
TOTAL CURRENT LIABILITIES 8,648.8       8,271.3       8,648.8 8,271.3        
Liabilities, Noncurrent                            
Deferred Income Taxes 7,086.5       6,813.9       7,086.5 6,813.9        
Regulatory Liabilities and Deferred Investment Tax Credits 8,540.3       8,422.3       8,540.3 8,422.3        
TOTAL NONCURRENT LIABILITIES 40,985.8       38,132.3       40,985.8 38,132.3        
TOTAL LIABILITIES 49,634.6       46,403.6       49,634.6 46,403.6        
Equity [Abstract]                            
Retained Earnings 9,325.3       8,626.7       9,325.3 8,626.7        
TOTAL LIABILITIES AND EQUITY 68,802.8       64,729.1       68,802.8 64,729.1        
Operating Activites                            
NET INCOME (LOSS) 364.8 579.7 530.1 456.7 401.8 556.7 376.2 594.2 1,931.3 1,928.9 618.0      
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:                            
Depreciation and Amortization                 2,286.6 1,997.2 1,962.3      
Deferred Income Taxes                 104.3 901.5 (50.0)      
Allowance for Equity Funds Used During Construction                 (132.5) (93.7) (113.2)      
Amortization of Deferred Property Taxes                 (59.1) (29.5) (19.0)      
Change in Other Noncurrent Assets                 119.8 (423.9) (454.6)      
Increase (Decrease) in Other Noncurrent Liabilities                 129.0 181.7 15.4      
Accounts Receivable, Net                 145.9 28.5 (226.6)      
Accounts Payable                 36.6 (58.0) 164.9      
Accrued Taxes, Net                 153.2 91.9 42.8      
Net Cash Provided by (Used in) Financing Activities                            
Cash and Cash Equivalents at Beginning of Period       214.6         214.6          
Cash and Cash Equivalents at End of Period $ 234.1       214.6       234.1 214.6        
Organization and Summary of Significant Accounting Policies (Textuals)                            
Issuance of Long-term Debt                 4,945.7 3,854.1 2,594.9      
Repayments of Long-term Debt                 $ 2,782.0 3,087.9 1,794.9      
Number of Equity Method Investments 2               2          
Equity Method Investment $ 846.2       812.3       $ 846.2 812.3        
Income (Loss) from Equity Method Investment                 $ 73.1 $ 82.4 $ 71.2      
Antidilutive Shares Outstanding | shares                 0 0 0      
Net Income (Loss) 364.8 579.7 530.1 456.7 401.8 556.7 376.2 594.2 $ 1,931.3 $ 1,928.9 $ 618.0      
Retained Earnings $ 9,325.3       8,626.7       $ 9,325.3 8,626.7        
ETT [Member]                            
Organization and Summary of Significant Accounting Policies (Textuals)                            
Equity Method Investment, Ownership Percentage 50.00%               50.00%          
Equity Method Investment $ 666.0       664.0       $ 666.0 664.0        
Income (Loss) from Equity Method Investment                 $ 62.0 82.0        
ETT [Member] | Berkshire Hathaway [Member]                            
Organization and Summary of Significant Accounting Policies (Textuals)                            
Equity Method Investment, Ownership Percentage 50.00%               50.00%          
ETT [Member] | AEP Transmission Holdco [Member]                            
Organization and Summary of Significant Accounting Policies (Textuals)                            
Equity Method Investment, Ownership Percentage 49.50%               49.50%          
ETT [Member] | AEP Transmission Partner [Member]                            
Organization and Summary of Significant Accounting Policies (Textuals)                            
Equity Method Investment, Ownership Percentage 0.50%               0.50%          
Pension Plans [Member] | Equity [Member]                            
Target Asset Allocations                            
Target Asset Allocation 25.00%               25.00%          
Pension Plans [Member] | Fixed Income [Member]                            
Target Asset Allocations                            
Target Asset Allocation 59.00%               59.00%          
Pension Plans [Member] | Other Investments [Member]                            
Target Asset Allocations                            
Target Asset Allocation 15.00%               15.00%          
Pension Plans [Member] | Cash and Cash Equivalents [Member]                            
Target Asset Allocations                            
Target Asset Allocation 1.00%               1.00%          
Other Postretirement Benefit Plans [Member] | Equity [Member]                            
Target Asset Allocations                            
Target Asset Allocation 49.00%               49.00%          
Other Postretirement Benefit Plans [Member] | Fixed Income [Member]                            
Target Asset Allocations                            
Target Asset Allocation 49.00%               49.00%          
Other Postretirement Benefit Plans [Member] | Cash and Cash Equivalents [Member]                            
Target Asset Allocations                            
Target Asset Allocation 2.00%               2.00%          
AEP Texas Inc. [Member]                            
Cash, Cash Equivalents and Restricted Cash                            
Cash and Cash Equivalents at Beginning of Period       2.0         $ 2.0          
Supplemental Income Statement Elements                            
Depreciation and Amortization of Property, Plant and Equipment                 262.2 221.1 204.0      
Amortization of Certain Securitized Assets                 240.0 231.4 210.3      
Amortization of Regulatory Assets and Liabilities                 (2.6) (2.4) (0.4)      
Utilities Operating Expense, Depreciation and Amortization                 499.6 450.1 413.9      
Cash Paid (Received) for:                            
Cash Paid for Interest, Net of Capitalized Amounts                 145.9 134.6 145.6      
Income Taxes Paid, Net                 7.9 (28.3) 38.2      
Construction in Progress Expenditures Incurred but Not yet Paid                 243.1 325.7 100.1      
Noncash Investing and Financing Activities:                            
Capital Lease Obligations Incurred                 10.6 8.2 7.1      
Construction Expenditures Included in Current Liabilities as of December 31,                 243.1 325.7 100.1      
Restricted Cash $ 156.7       155.2       156.7 155.2        
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents 159.8       157.2       159.8 157.2 $ 146.9     208.4
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations 159.8       157.2       $ 159.8 $ 157.2        
Risks and Uncertainties                            
Percentage of Significant Customers Concentration Risk                 10.00% 10.00% 10.00%      
Amounts Attributable to AEP Common Shareholders                            
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest                 $ 211.3 $ 310.5 $ 195.4      
Revenues                            
TOTAL REVENUES 402.0 433.4 388.3 371.6 374.1 431.2 389.5 343.6 1,595.3 1,538.4 1,461.4      
Expenses                            
Depreciation and Amortization                 499.6 450.1 413.9      
TOTAL EXPENSES                 1,249.0 1,122.3 1,085.1      
OPERATING INCOME (LOSS) 84.3 94.0 86.2 81.8 96.2 [2] 128.8 [2] 108.8 [2] 82.3 [2] 346.3 416.1 376.3      
Other Income (Expense)                            
Allowance for Equity Funds Used During Construction                 20.0 6.8 9.2      
Interest Expense                 (147.3) (142.3) (144.4)      
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) AND EQUITY EARNINGS (LOSS)                 232.1 287.1 255.3      
Income Tax Expense (Benefit)                 20.8 (23.4) 59.9      
NET INCOME (LOSS) 60.2 57.8 46.5 46.8 163.9 64.3 49.0 33.3 211.3 310.5 146.6      
Accounts Receivable:                            
Customers 110.9       105.3       110.9 105.3        
Total Accounts Receivable 196.9       194.0       196.9 194.0        
Accrued Tax Benefits 44.9       41.0       44.9 41.0        
TOTAL CURRENT ASSETS 476.5       563.8       476.5 563.8        
Property, Plant and Equipment                            
Transmission 3,683.6       3,053.6       3,683.6 3,053.6        
Other Property, Plant and Equipment 727.9       461.0       727.9 461.0        
Construction Work in Progress 836.2       835.7       836.2 835.7        
Total Property, Plant and Equipment 9,643.0       8,419.6       9,643.0 8,419.6        
Accumulated Depreciation and Amortization 1,651.2       1,594.5       1,651.2 1,594.5        
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET 7,991.8       6,825.1       7,991.8 6,825.1        
Other Noncurrent Assets                            
TOTAL OTHER NONCURRENT ASSETS 1,135.4       1,384.7       1,135.4 1,384.7        
TOTAL ASSETS 9,603.7       8,773.6       9,603.7 8,773.6        
Current Liabilities                            
Accounts Payable 276.5       379.4       276.5 379.4        
Affiliated Companies 30.3       30.2       30.3 30.2        
Accrued Taxes 75.5       77.2       75.5 77.2        
TOTAL CURRENT LIABILITIES 1,259.5       871.5       1,259.5 871.5        
Liabilities, Noncurrent                            
Deferred Income Taxes 913.1       913.1       913.1 913.1        
Regulatory Liabilities and Deferred Investment Tax Credits 1,344.3       1,320.5       1,344.3 1,320.5        
TOTAL NONCURRENT LIABILITIES 5,763.7       5,732.2       5,763.7 5,732.2        
TOTAL LIABILITIES 7,023.2       6,603.7       7,023.2 6,603.7        
Equity [Abstract]                            
Retained Earnings 1,337.7       1,124.6       1,337.7 1,124.6        
TOTAL LIABILITIES AND EQUITY 9,603.7       8,773.6       9,603.7 8,773.6        
Operating Activites                            
NET INCOME (LOSS) 60.2 57.8 46.5 46.8 163.9 64.3 49.0 33.3 211.3 310.5 146.6      
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:                            
Depreciation and Amortization                 499.6 450.1 413.9      
Deferred Income Taxes                 (16.5) 63.3 29.5      
Allowance for Equity Funds Used During Construction                 (20.0) (6.8) (9.2)      
Change in Other Noncurrent Assets                 (35.4) (49.4) (44.1)      
Increase (Decrease) in Other Noncurrent Liabilities                 44.9 8.8 (10.3)      
Accounts Receivable, Net                 (2.9) (23.5) (22.6)      
Accounts Payable                 (20.3) 30.8 (3.0)      
Accrued Taxes, Net                 (5.6) (31.3) (22.6)      
Net Cash Provided by (Used in) Financing Activities                            
Cash and Cash Equivalents at Beginning of Period       2.0         2.0          
Cash and Cash Equivalents at End of Period 3.1       2.0       3.1 2.0        
Organization and Summary of Significant Accounting Policies (Textuals)                            
Issuance of Long-term Debt                 494.0 749.6 199.2      
Repayments of Long-term Debt                 266.1 323.1 428.7      
Net Income (Loss) 60.2 57.8 46.5 46.8 163.9 64.3 49.0 33.3 211.3 310.5 146.6      
Retained Earnings $ 1,337.7       1,124.6       $ 1,337.7 1,124.6        
AEP Texas Inc. [Member] | Pension Plans [Member] | Equity [Member]                            
Target Asset Allocations                            
Target Asset Allocation 25.00%               25.00%          
AEP Texas Inc. [Member] | Pension Plans [Member] | Fixed Income [Member]                            
Target Asset Allocations                            
Target Asset Allocation 59.00%               59.00%          
AEP Texas Inc. [Member] | Pension Plans [Member] | Other Investments [Member]                            
Target Asset Allocations                            
Target Asset Allocation 15.00%               15.00%          
AEP Texas Inc. [Member] | Pension Plans [Member] | Cash and Cash Equivalents [Member]                            
Target Asset Allocations                            
Target Asset Allocation 1.00%               1.00%          
AEP Texas Inc. [Member] | Other Postretirement Benefit Plans [Member] | Equity [Member]                            
Target Asset Allocations                            
Target Asset Allocation 49.00%               49.00%          
AEP Texas Inc. [Member] | Other Postretirement Benefit Plans [Member] | Fixed Income [Member]                            
Target Asset Allocations                            
Target Asset Allocation 49.00%               49.00%          
AEP Texas Inc. [Member] | Other Postretirement Benefit Plans [Member] | Cash and Cash Equivalents [Member]                            
Target Asset Allocations                            
Target Asset Allocation 2.00%               2.00%          
AEP Transmission Co [Member]                            
Cash, Cash Equivalents and Restricted Cash                            
Cash and Cash Equivalents at Beginning of Period       0.0       0.0 $ 0.0 0.0 0.0      
Supplemental Income Statement Elements                            
Depreciation and Amortization of Property, Plant and Equipment                 133.9 95.7 [3] 65.9      
Amortization of Certain Securitized Assets                 0.0 0.0 0.0      
Amortization of Regulatory Assets and Liabilities                 0.0 0.0 0.0      
Utilities Operating Expense, Depreciation and Amortization                 133.9 95.7 [3],[4] 65.9      
Cash Paid (Received) for:                            
Cash Paid for Interest, Net of Capitalized Amounts                 80.2 62.4 42.0      
Income Taxes Paid, Net                 (30.7) (107.3) (235.1)      
Construction in Progress Expenditures Incurred but Not yet Paid                 345.0 485.0 298.3      
Noncash Investing and Financing Activities:                            
Capital Lease Obligations Incurred                 0.0 0.2 0.0      
Construction Expenditures Included in Current Liabilities as of December 31,                 $ 345.0 $ 485.0 $ 298.3      
Risks and Uncertainties                            
Percentage of Significant Customers Concentration Risk                 10.00% 10.00% 10.00%      
Revenues                            
TOTAL REVENUES $ 189.9 [5] 194.4 [5] 200.1 [5] 191.7 [5] 159.2 165.6 229.4 152.7 $ 776.1 $ 706.9 [4] $ 478.0      
Expenses                            
Depreciation and Amortization                 133.9 95.7 [3],[4] 65.9      
TOTAL EXPENSES                 366.0 274.0 197.9      
OPERATING INCOME (LOSS) 91.5 [5] 97.0 [5] 110.5 [5] 111.1 [5] 83.5 [2] 93.6 [2] 165.4 [2] 90.4 [2] 410.1 432.9 280.1      
Other Income (Expense)                            
Allowance for Equity Funds Used During Construction                 70.6 49.0 [4],[6] 52.3      
Interest Expense                 (83.2) (70.2) [4] (46.0)      
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) AND EQUITY EARNINGS (LOSS)                 400.0 412.9 286.8      
Income Tax Expense (Benefit)                 84.1 142.2 [4],[7] 94.1      
NET INCOME (LOSS) 71.7 [5] 78.1 [5] 82.0 [5] 84.1 [5] 47.7 58.6 107.4 57.0 315.9 270.7 [4],[7] 192.7      
Accounts Receivable:                            
Customers 11.8       15.0       11.8 15.0        
Total Accounts Receivable 72.8       109.5       72.8 109.5        
Accrued Tax Benefits 33.4       49.4       33.4 49.4        
TOTAL CURRENT ASSETS 225.5       326.4       225.5 326.4        
Property, Plant and Equipment                            
Transmission 6,515.8       5,319.7       6,515.8 5,319.7        
Other Property, Plant and Equipment 174.0       126.8       174.0 126.8        
Construction Work in Progress 1,578.3       1,324.0       1,578.3 1,324.0        
Total Property, Plant and Equipment 8,268.1       6,770.5 [4]       8,268.1 6,770.5 [4]        
Accumulated Depreciation and Amortization 271.9       152.6 [4]       271.9 152.6 [4]        
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET 7,996.2       6,617.9 [4],[8]       7,996.2 6,617.9 [4],[8]        
Other Noncurrent Assets                            
Deferred Property Taxes 157.9       125.0       157.9 125.0        
TOTAL OTHER NONCURRENT ASSETS 172.4       137.8       172.4 137.8        
TOTAL ASSETS 8,394.1       7,082.1 [4]       8,394.1 7,082.1 [4] 5,349.8      
Current Liabilities                            
Accounts Payable 347.2       484.5       347.2 484.5        
Affiliated Companies 56.0       66.1       56.0 66.1        
Accrued Taxes 288.9       231.5       288.9 231.5        
TOTAL CURRENT LIABILITIES 842.2       866.9       842.2 866.9        
Liabilities, Noncurrent                            
Deferred Income Taxes 704.4       600.4       704.4 600.4        
Regulatory Liabilities and Deferred Investment Tax Credits 521.3       493.8       521.3 493.8        
TOTAL NONCURRENT LIABILITIES 3,982.1       3,625.3       3,982.1 3,625.3        
TOTAL LIABILITIES 4,824.3       4,492.2       4,824.3 4,492.2        
Equity [Abstract]                            
Retained Earnings 1,089.2       773.3       1,089.2 773.3        
TOTAL MEMBER'S EQUITY 3,569.8       2,589.9       3,569.8 2,589.9 1,957.6     1,552.9
TOTAL LIABILITIES AND EQUITY 8,394.1       7,082.1       8,394.1 7,082.1        
Operating Activites                            
NET INCOME (LOSS) 71.7 [5] 78.1 [5] 82.0 [5] 84.1 [5] 47.7 58.6 107.4 57.0 315.9 270.7 [4],[7] 192.7      
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:                            
Depreciation and Amortization                 133.9 95.7 [3],[4] 65.9      
Deferred Income Taxes                 98.9 271.5 223.1      
Allowance for Equity Funds Used During Construction                 (70.6) (49.0) [4],[6] (52.3)      
Amortization of Deferred Property Taxes                 (32.9) (22.8) (15.3)      
Change in Other Noncurrent Assets                 14.6 11.0 (2.8)      
Increase (Decrease) in Other Noncurrent Liabilities                 17.4 27.5 4.4      
Accounts Receivable, Net                 36.7 (30.4) (22.6)      
Accounts Payable                 (7.5) 23.0 14.3      
Accrued Taxes, Net                 73.4 16.3 143.8      
Net Cash Flows from (Used for) Operating Activities                 548.6 604.8 548.9      
Investing Activities                            
Net Cash Flows from (Used for) Investing Activities                 (1,513.3) (1,595.6) (1,135.0)      
Net Cash Provided by (Used in) Financing Activities                            
Net Cash Flows from (Used for) Financing Activities                 964.7 990.8 586.1      
Net Increase (Decrease) in Cash and Cash Equivalents                 0.0 0.0 0.0      
Cash and Cash Equivalents at Beginning of Period       0.0       0.0 0.0 0.0 0.0      
Cash and Cash Equivalents at End of Period 0.0       0.0       0.0 0.0 0.0      
Organization and Summary of Significant Accounting Policies (Textuals)                            
Issuance of Long-term Debt                 321.0 617.6 686.9      
Repayments of Long-term Debt                 50.0 0.0 300.0      
Net Income (Loss) 71.7 [5] 78.1 [5] 82.0 [5] 84.1 [5] 47.7 58.6 107.4 57.0 315.9 270.7 [4],[7] 192.7      
Retained Earnings 1,089.2       773.3       1,089.2 773.3        
Appalachian Power Co [Member]                            
Cash, Cash Equivalents and Restricted Cash                            
Cash and Cash Equivalents at Beginning of Period       2.9         2.9          
Supplemental Income Statement Elements                            
Depreciation and Amortization of Property, Plant and Equipment                 428.1 407.6 387.6      
Amortization of Certain Securitized Assets                 0.0 0.0 0.0      
Amortization of Regulatory Assets and Liabilities                 0.3 0.3 0.9      
Utilities Operating Expense, Depreciation and Amortization                 428.4 407.9 388.5      
Cash Paid (Received) for:                            
Cash Paid for Interest, Net of Capitalized Amounts                 182.0 183.6 181.8      
Income Taxes Paid, Net                 (13.0) 31.2 22.1      
Construction in Progress Expenditures Incurred but Not yet Paid                 134.4 126.3 151.6      
Noncash Investing and Financing Activities:                            
Capital Lease Obligations Incurred                 5.5 3.5 6.1      
Construction Expenditures Included in Current Liabilities as of December 31,                 134.4 126.3 151.6      
Restricted Cash 25.6       16.3       25.6 16.3        
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents 29.8       19.2       $ 29.8 $ 19.2 $ 18.5     17.6
Risks and Uncertainties                            
Percentage of Significant Customers Concentration Risk                 10.00% 10.00% 10.00%      
Revenues                            
TOTAL REVENUES 718.1 762.0 667.0 820.4 746.8 719.3 675.3 792.8 $ 2,967.5 $ 2,934.2 $ 3,001.2      
Expenses                            
Depreciation and Amortization                 428.4 407.9 388.5      
TOTAL EXPENSES                 2,484.0 2,243.9 2,262.9      
OPERATING INCOME (LOSS) 108.1 49.8 132.6 193.0 173.6 [2] 171.7 [2] 126.1 [2] 218.9 [2] 483.5 690.3 738.3      
Other Income (Expense)                            
Allowance for Equity Funds Used During Construction                 13.2 9.2 11.7      
Interest Expense                 (194.8) (190.9) (188.5)      
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) AND EQUITY EARNINGS (LOSS)                 322.9 516.6 568.2      
Income Tax Expense (Benefit)                 (44.9) 185.3 199.1      
NET INCOME (LOSS) 77.8 87.1 77.4 125.5 82.6 86.0 52.1 110.6 367.8 331.3 369.1      
Accounts Receivable:                            
Customers 146.5       123.1       146.5 123.1        
Total Accounts Receivable 283.4       263.9       283.4 263.9        
TOTAL CURRENT ASSETS 698.7       636.2       698.7 636.2        
Property, Plant and Equipment                            
Transmission 3,317.7       3,019.9       3,317.7 3,019.9        
Other Property, Plant and Equipment 485.8       427.9       485.8 427.9        
Construction Work in Progress 490.2       483.0       490.2 483.0        
Total Property, Plant and Equipment 14,792.7       14,141.5       14,792.7 14,141.5        
Accumulated Depreciation and Amortization 4,124.4       3,896.4       4,124.4 3,896.4        
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET 10,668.3       10,245.1       10,668.3 10,245.1        
Other Noncurrent Assets                            
TOTAL OTHER NONCURRENT ASSETS 923.5       1,047.3       923.5 1,047.3        
TOTAL ASSETS 12,290.5       11,928.6       12,290.5 11,928.6        
Current Liabilities                            
Accounts Payable 263.8       264.9       263.8 264.9        
Affiliated Companies 84.0       92.7       84.0 92.7        
Accrued Taxes 89.3       94.5       89.3 94.5        
TOTAL CURRENT LIABILITIES 1,354.0       1,124.2       1,354.0 1,124.2        
Liabilities, Noncurrent                            
Deferred Income Taxes 1,625.8       1,565.7       1,625.8 1,565.7        
Regulatory Liabilities and Deferred Investment Tax Credits 1,449.7       1,454.9       1,449.7 1,454.9        
TOTAL NONCURRENT LIABILITIES 6,930.4       6,999.9       6,930.4 6,999.9        
TOTAL LIABILITIES 8,284.4       8,124.1       8,284.4 8,124.1        
Equity [Abstract]                            
Retained Earnings 1,922.0       1,714.1       1,922.0 1,714.1        
TOTAL LIABILITIES AND EQUITY 12,290.5       11,928.6       12,290.5 11,928.6        
Operating Activites                            
NET INCOME (LOSS) 77.8 87.1 77.4 125.5 82.6 86.0 52.1 110.6 367.8 331.3 369.1      
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:                            
Depreciation and Amortization                 428.4 407.9 388.5      
Deferred Income Taxes                 (16.8) 171.5 130.7      
Allowance for Equity Funds Used During Construction                 (13.2) (9.2) (11.7)      
Change in Other Noncurrent Assets                 59.4 12.8 3.4      
Increase (Decrease) in Other Noncurrent Liabilities                 (4.8) 11.9 (26.1)      
Accounts Receivable, Net                 33.6 (28.0) (48.0)      
Accounts Payable                 (13.3) 37.5 19.5      
Accrued Taxes, Net                 (13.2) (12.7) 53.7      
Net Cash Flows from (Used for) Operating Activities                 846.6 880.0 894.7      
Investing Activities                            
Net Cash Flows from (Used for) Investing Activities                 (769.4) (802.3) (631.9)      
Net Cash Provided by (Used in) Financing Activities                            
Net Cash Flows from (Used for) Financing Activities                 (66.6) (77.0) (261.9)      
Cash and Cash Equivalents at Beginning of Period       2.9         2.9          
Cash and Cash Equivalents at End of Period 4.2       2.9       4.2 2.9        
Organization and Summary of Significant Accounting Policies (Textuals)                            
Issuance of Long-term Debt                 203.2 320.9 314.0      
Repayments of Long-term Debt                 124.0 377.9 213.6      
Net Income (Loss) 77.8 87.1 77.4 125.5 82.6 86.0 52.1 110.6 367.8 331.3 369.1      
Retained Earnings $ 1,922.0       1,714.1       $ 1,922.0 1,714.1        
Appalachian Power Co [Member] | Pension Plans [Member] | Equity [Member]                            
Target Asset Allocations                            
Target Asset Allocation 25.00%               25.00%          
Appalachian Power Co [Member] | Pension Plans [Member] | Fixed Income [Member]                            
Target Asset Allocations                            
Target Asset Allocation 59.00%               59.00%          
Appalachian Power Co [Member] | Pension Plans [Member] | Other Investments [Member]                            
Target Asset Allocations                            
Target Asset Allocation 15.00%               15.00%          
Appalachian Power Co [Member] | Pension Plans [Member] | Cash and Cash Equivalents [Member]                            
Target Asset Allocations                            
Target Asset Allocation 1.00%               1.00%          
Appalachian Power Co [Member] | Other Postretirement Benefit Plans [Member] | Equity [Member]                            
Target Asset Allocations                            
Target Asset Allocation 49.00%               49.00%          
Appalachian Power Co [Member] | Other Postretirement Benefit Plans [Member] | Fixed Income [Member]                            
Target Asset Allocations                            
Target Asset Allocation 49.00%               49.00%          
Appalachian Power Co [Member] | Other Postretirement Benefit Plans [Member] | Cash and Cash Equivalents [Member]                            
Target Asset Allocations                            
Target Asset Allocation 2.00%               2.00%          
Indiana Michigan Power Co [Member]                            
Cash, Cash Equivalents and Restricted Cash                            
Cash and Cash Equivalents at Beginning of Period       1.3       1.2 $ 1.3 1.2 1.1      
AEP Consolidated Revenues - Other Revenues:                            
Ohio Valley Electric Corporation - Barging and Other Transportation Services (43.47% Owned)                 63.4 62.6 62.1      
Supplemental Income Statement Elements                            
Depreciation and Amortization of Property, Plant and Equipment                 278.9 203.1 183.9      
Amortization of Certain Securitized Assets                 0.0 0.0 0.0      
Amortization of Regulatory Assets and Liabilities                 14.2 7.8 7.8      
Utilities Operating Expense, Depreciation and Amortization                 293.1 210.9 191.7      
Cash Paid (Received) for:                            
Cash Paid for Interest, Net of Capitalized Amounts                 116.9 94.8 83.3      
Income Taxes Paid, Net                 32.6 (89.9) (39.5)      
Construction in Progress Expenditures Incurred but Not yet Paid                 93.0 88.5 106.2      
Noncash Investing and Financing Activities:                            
Capital Lease Obligations Incurred                 5.8 7.1 18.2      
Construction Expenditures Included in Current Liabilities as of December 31,                 93.0 88.5 106.2      
Acquisition of Nuclear Fuel Included in Current Liabilities as of December 31,                 4.0 0.0 2.1      
Expected Reimbursement For Spent Nuclear Fuel Dry Cask Storage                 $ 2.2 $ 2.6 $ 0.7      
Risks and Uncertainties                            
Percentage of Significant Customers Concentration Risk                 10.00% 10.00% 10.00%      
Revenues                            
TOTAL REVENUES $ 574.5 629.7 589.7 576.8 535.7 557.7 467.3 560.5 $ 2,370.7 $ 2,121.2 $ 2,167.6      
Expenses                            
Depreciation and Amortization                 293.1 210.9 191.7      
TOTAL EXPENSES                 1,993.5 1,774.0 1,793.3      
OPERATING INCOME (LOSS) 52.2 110.2 117.4 97.4 82.8 [2] 113.6 [2] 33.6 [2] 117.2 [2] 377.2 347.2 374.3      
Other Income (Expense)                            
Allowance for Equity Funds Used During Construction                 11.9 11.1 15.3      
Interest Expense                 (124.1) (110.8) (100.8)      
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) AND EQUITY EARNINGS (LOSS)                 290.4 268.1 307.4      
Income Tax Expense (Benefit)                 29.1 81.4 67.5      
NET INCOME (LOSS) 29.7 72.7 94.7 64.2 42.9 64.9 10.5 68.4 261.3 186.7 239.9      
Accounts Receivable:                            
Customers 63.1       56.4       63.1 56.4        
Total Accounts Receivable 143.0       115.6       143.0 115.6        
Accrued Tax Benefits 26.6       58.4       26.6 58.4        
TOTAL CURRENT ASSETS 430.4       434.0       430.4 434.0        
Property, Plant and Equipment                            
Transmission 1,576.8       1,504.0       1,576.8 1,504.0        
Other Property, Plant and Equipment 583.8       595.2       583.8 595.2        
Construction Work in Progress 465.3       460.2       465.3 460.2        
Total Property, Plant and Equipment 9,762.8       9,074.6       9,762.8 9,074.6        
Accumulated Depreciation and Amortization 3,151.6       3,024.2       3,151.6 3,024.2        
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET 6,611.2       6,050.4       6,611.2 6,050.4        
Other Noncurrent Assets                            
TOTAL OTHER NONCURRENT ASSETS 3,181.0       3,287.6       3,181.0 3,287.6        
TOTAL ASSETS 10,222.6       9,772.0       10,222.6 9,772.0        
Current Liabilities                            
Accounts Payable 174.7       154.5       174.7 154.5        
Affiliated Companies 70.2       98.3       70.2 98.3        
Accrued Taxes 90.7       81.3       90.7 81.3        
TOTAL CURRENT LIABILITIES 698.1       1,211.3       698.1 1,211.3        
Liabilities, Noncurrent                            
Deferred Income Taxes 948.0       953.8       948.0 953.8        
Regulatory Liabilities and Deferred Investment Tax Credits 1,574.5       1,708.7       1,574.5 1,708.7        
TOTAL NONCURRENT LIABILITIES 7,171.7       6,343.1       7,171.7 6,343.1        
TOTAL LIABILITIES 7,869.8       7,554.4       7,869.8 7,554.4        
Equity [Abstract]                            
Retained Earnings 1,329.1       1,192.2       1,329.1 1,192.2        
TOTAL LIABILITIES AND EQUITY 10,222.6       9,772.0       10,222.6 9,772.0        
Operating Activites                            
NET INCOME (LOSS) 29.7 72.7 94.7 64.2 42.9 64.9 10.5 68.4 261.3 186.7 239.9      
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:                            
Depreciation and Amortization                 293.1 210.9 191.7      
Deferred Income Taxes                 (42.9) 200.7 105.1      
Allowance for Equity Funds Used During Construction                 (11.9) (11.1) (15.3)      
Change in Other Noncurrent Assets                 (32.6) (88.4) (56.4)      
Increase (Decrease) in Other Noncurrent Liabilities                 72.1 37.4 58.2      
Accounts Receivable, Net                 4.8 (1.1) 0.5      
Accounts Payable                 (14.1) 17.6 11.6      
Accrued Taxes, Net                 41.2 (16.6) 6.0      
Net Cash Flows from (Used for) Operating Activities                 725.7 661.3 529.7      
Investing Activities                            
Net Cash Flows from (Used for) Investing Activities                 (654.8) (790.9) (760.1)      
Net Cash Provided by (Used in) Financing Activities                            
Net Cash Flows from (Used for) Financing Activities                 (69.8) 129.7 230.5      
Net Increase (Decrease) in Cash and Cash Equivalents                 1.1 0.1 0.1      
Cash and Cash Equivalents at Beginning of Period       1.3       1.2 1.3 1.2 1.1      
Cash and Cash Equivalents at End of Period 2.4       1.3       2.4 1.3 1.2      
Organization and Summary of Significant Accounting Policies (Textuals)                            
Issuance of Long-term Debt                 1,168.1 530.1 569.4      
Repayments of Long-term Debt                 884.9 260.7 100.2      
Net Income (Loss) 29.7 72.7 94.7 64.2 42.9 64.9 10.5 68.4 261.3 186.7 239.9      
Retained Earnings $ 1,329.1       1,192.2       $ 1,329.1 1,192.2        
Indiana Michigan Power Co [Member] | Pension Plans [Member] | Equity [Member]                            
Target Asset Allocations                            
Target Asset Allocation 25.00%               25.00%          
Indiana Michigan Power Co [Member] | Pension Plans [Member] | Fixed Income [Member]                            
Target Asset Allocations                            
Target Asset Allocation 59.00%               59.00%          
Indiana Michigan Power Co [Member] | Pension Plans [Member] | Other Investments [Member]                            
Target Asset Allocations                            
Target Asset Allocation 15.00%               15.00%          
Indiana Michigan Power Co [Member] | Pension Plans [Member] | Cash and Cash Equivalents [Member]                            
Target Asset Allocations                            
Target Asset Allocation 1.00%               1.00%          
Indiana Michigan Power Co [Member] | Other Postretirement Benefit Plans [Member] | Equity [Member]                            
Target Asset Allocations                            
Target Asset Allocation 49.00%               49.00%          
Indiana Michigan Power Co [Member] | Other Postretirement Benefit Plans [Member] | Fixed Income [Member]                            
Target Asset Allocations                            
Target Asset Allocation 49.00%               49.00%          
Indiana Michigan Power Co [Member] | Other Postretirement Benefit Plans [Member] | Cash and Cash Equivalents [Member]                            
Target Asset Allocations                            
Target Asset Allocation 2.00%               2.00%          
Ohio Power Co [Member]                            
Cash, Cash Equivalents and Restricted Cash                            
Cash and Cash Equivalents at Beginning of Period       3.1         $ 3.1          
Supplemental Income Statement Elements                            
Depreciation and Amortization of Property, Plant and Equipment                 232.6 200.9 202.3      
Amortization of Certain Securitized Assets                 47.9 44.4 44.3      
Amortization of Regulatory Assets and Liabilities                 (20.8) (19.4) (8.0)      
Utilities Operating Expense, Depreciation and Amortization                 259.7 225.9 238.6      
Cash Paid (Received) for:                            
Cash Paid for Interest, Net of Capitalized Amounts                 97.1 100.0 109.9      
Income Taxes Paid, Net                 51.3 48.5 220.4      
Construction in Progress Expenditures Incurred but Not yet Paid                 98.2 87.8 44.6      
Noncash Investing and Financing Activities:                            
Capital Lease Obligations Incurred                 4.4 4.5 3.4      
Construction Expenditures Included in Current Liabilities as of December 31,                 98.2 87.8 44.6      
Restricted Cash $ 27.6       26.6       27.6 26.6        
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents 32.5       29.7       $ 32.5 $ 29.7 $ 30.3     $ 30.8
Risks and Uncertainties                            
Percentage of Significant Customers Concentration Risk                 10.00% 10.00% 10.00%      
Revenues                            
TOTAL REVENUES 745.4 778.3 748.8 790.9 731.9 742.0 663.9 746.1 $ 3,063.4 $ 2,883.9 $ 2,953.9      
Expenses                            
Depreciation and Amortization                 259.7 225.9 238.6      
TOTAL EXPENSES                 2,643.6 2,318.2 2,449.8      
OPERATING INCOME (LOSS) 118.2 79.9 104.4 117.3 144.2 [2] 153.4 [2] 118.5 [2] 149.6 [2] 419.8 565.7 504.1      
Other Income (Expense)                            
Allowance for Equity Funds Used During Construction                 9.8 6.4 6.0      
Interest Expense                 (100.7) (101.9) (112.2)      
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) AND EQUITY EARNINGS (LOSS)                 349.5 483.2 426.0      
Income Tax Expense (Benefit)                 24.0 159.3 143.8      
NET INCOME (LOSS) 88.4 88.7 68.8 79.6 92.8 82.6 62.3 86.2 325.5 323.9 282.2      
Accounts Receivable:                            
Customers 111.1       67.8       111.1 67.8        
Total Accounts Receivable 202.6       169.0       202.6 169.0        
TOTAL CURRENT ASSETS 319.6       397.9       319.6 397.9        
Property, Plant and Equipment                            
Transmission 2,544.3       2,419.2       2,544.3 2,419.2        
Other Property, Plant and Equipment 574.8       495.9       574.8 495.9        
Construction Work in Progress 432.1       410.1       432.1 410.1        
Total Property, Plant and Equipment 8,493.5       7,951.6       8,493.5 7,951.6        
Accumulated Depreciation and Amortization 2,218.6       2,184.8       2,218.6 2,184.8        
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET 6,274.9       5,766.8       6,274.9 5,766.8        
Other Noncurrent Assets                            
TOTAL OTHER NONCURRENT ASSETS 841.4       1,097.0       841.4 1,097.0        
TOTAL ASSETS 7,435.9       7,261.7       7,435.9 7,261.7        
Current Liabilities                            
Accounts Payable 211.9       205.8       211.9 205.8        
Affiliated Companies 102.9       118.2       102.9 118.2        
Accrued Taxes 537.8       512.5       537.8 512.5        
TOTAL CURRENT LIABILITIES 1,347.7       1,593.8       1,347.7 1,593.8        
Liabilities, Noncurrent                            
Deferred Income Taxes 763.3       762.9       763.3 762.9        
Regulatory Liabilities and Deferred Investment Tax Credits 1,221.2       1,100.2       1,221.2 1,100.2        
TOTAL NONCURRENT LIABILITIES 3,790.8       3,357.6       3,790.8 3,357.6        
TOTAL LIABILITIES 5,138.5       4,951.4       5,138.5 4,951.4        
Equity [Abstract]                            
Retained Earnings 1,136.4       1,148.4       1,136.4 1,148.4        
TOTAL LIABILITIES AND EQUITY 7,435.9       7,261.7       7,435.9 7,261.7        
Operating Activites                            
NET INCOME (LOSS) 88.4 88.7 68.8 79.6 92.8 82.6 62.3 86.2 325.5 323.9 282.2      
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:                            
Depreciation and Amortization                 259.7 225.9 238.6      
Deferred Income Taxes                 (36.2) 147.9 (39.2)      
Allowance for Equity Funds Used During Construction                 (9.8) (6.4) (6.0)      
Amortization of Deferred Property Taxes                 (12.5) (17.9) (9.8)      
Change in Other Noncurrent Assets                 (9.8) (51.1) (44.6)      
Increase (Decrease) in Other Noncurrent Liabilities                 53.8 15.8 31.0      
Accounts Receivable, Net                 43.1 (30.1) (26.6)      
Accounts Payable                 (13.8) 11.6 13.7      
Accrued Taxes, Net                 26.8 (9.4) (6.0)      
Net Cash Flows from (Used for) Operating Activities                 1,028.7 622.2 646.3      
Investing Activities                            
Net Cash Flows from (Used for) Investing Activities                 (707.5) (530.9) (97.3)      
Net Cash Provided by (Used in) Financing Activities                            
Net Cash Flows from (Used for) Financing Activities                 (318.4) (91.9) (549.5)      
Cash and Cash Equivalents at Beginning of Period       3.1         3.1          
Cash and Cash Equivalents at End of Period 4.9       3.1       4.9 3.1        
Organization and Summary of Significant Accounting Policies (Textuals)                            
Issuance of Long-term Debt                 392.8 0.0 0.0      
Repayments of Long-term Debt                 397.1 46.4 395.9      
Net Income (Loss) 88.4 88.7 68.8 79.6 92.8 82.6 62.3 86.2 325.5 323.9 282.2      
Retained Earnings $ 1,136.4       1,148.4       $ 1,136.4 1,148.4        
Ohio Power Co [Member] | Pension Plans [Member] | Equity [Member]                            
Target Asset Allocations                            
Target Asset Allocation 25.00%               25.00%          
Ohio Power Co [Member] | Pension Plans [Member] | Fixed Income [Member]                            
Target Asset Allocations                            
Target Asset Allocation 59.00%               59.00%          
Ohio Power Co [Member] | Pension Plans [Member] | Other Investments [Member]                            
Target Asset Allocations                            
Target Asset Allocation 15.00%               15.00%          
Ohio Power Co [Member] | Pension Plans [Member] | Cash and Cash Equivalents [Member]                            
Target Asset Allocations                            
Target Asset Allocation 1.00%               1.00%          
Ohio Power Co [Member] | Other Postretirement Benefit Plans [Member] | Equity [Member]                            
Target Asset Allocations                            
Target Asset Allocation 49.00%               49.00%          
Ohio Power Co [Member] | Other Postretirement Benefit Plans [Member] | Fixed Income [Member]                            
Target Asset Allocations                            
Target Asset Allocation 49.00%               49.00%          
Ohio Power Co [Member] | Other Postretirement Benefit Plans [Member] | Cash and Cash Equivalents [Member]                            
Target Asset Allocations                            
Target Asset Allocation 2.00%               2.00%          
Public Service Co Of Oklahoma [Member]                            
Cash, Cash Equivalents and Restricted Cash                            
Cash and Cash Equivalents at Beginning of Period       1.6       1.5 $ 1.6 1.5 1.4      
Supplemental Income Statement Elements                            
Depreciation and Amortization of Property, Plant and Equipment                 155.5 131.4 122.6      
Amortization of Certain Securitized Assets                 0.0 0.0 0.0      
Amortization of Regulatory Assets and Liabilities                 8.5 (1.0) 7.6      
Utilities Operating Expense, Depreciation and Amortization                 164.0 130.4 130.2      
Cash Paid (Received) for:                            
Cash Paid for Interest, Net of Capitalized Amounts                 62.0 61.5 60.1      
Income Taxes Paid, Net                 17.9 (72.6) (37.7)      
Construction in Progress Expenditures Incurred but Not yet Paid                 33.2 23.1 33.6      
Noncash Investing and Financing Activities:                            
Capital Lease Obligations Incurred                 4.3 2.1 3.1      
Construction Expenditures Included in Current Liabilities as of December 31,                 $ 33.2 $ 23.1 $ 33.6      
Risks and Uncertainties                            
Percentage of Significant Customers Concentration Risk                 10.00% 10.00% 10.00%      
Revenues                            
TOTAL REVENUES $ 330.8 481.4 398.3 336.8 335.6 442.8 344.7 304.1 $ 1,547.3 $ 1,427.2 $ 1,249.8      
Expenses                            
Depreciation and Amortization                 164.0 130.4 130.2      
TOTAL EXPENSES                 1,404.8 1,255.7 1,054.2      
OPERATING INCOME (LOSS) 2.9 78.5 57.2 3.9 20.4 [2] 85.9 [2] 45.3 [2] 19.9 [2] 142.5 171.5 195.6      
Other Income (Expense)                            
Allowance for Equity Funds Used During Construction                 0.4 0.5 6.2      
Interest Expense                 (63.5) (53.4) (51.2)      
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) AND EQUITY EARNINGS (LOSS)                 88.2 122.1 154.4      
Income Tax Expense (Benefit)                 5.0 50.1 54.4      
NET INCOME (LOSS) (6.6) 60.4 36.6 (7.2) 0.6 46.2 20.4 4.8 83.2 72.0 100.0      
Accounts Receivable:                            
Customers 32.5       32.5       32.5 32.5        
Total Accounts Receivable 64.3       69.4       64.3 69.4        
Accrued Tax Benefits 14.7       28.1       14.7 28.1        
TOTAL CURRENT ASSETS 157.9       205.3       157.9 205.3        
Property, Plant and Equipment                            
Transmission 892.3       858.8       892.3 858.8        
Other Property, Plant and Equipment 303.5       287.4       303.5 287.4        
Construction Work in Progress 94.0       111.3       94.0 111.3        
Total Property, Plant and Equipment 5,439.6       5,279.8       5,439.6 5,279.8        
Accumulated Depreciation and Amortization 1,472.9       1,393.6       1,472.9 1,393.6        
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET 3,966.7       3,886.2       3,966.7 3,886.2        
Other Noncurrent Assets                            
TOTAL OTHER NONCURRENT ASSETS 407.8       416.8       407.8 416.8        
TOTAL ASSETS 4,532.4       4,508.3       4,532.4 4,508.3        
Current Liabilities                            
Accounts Payable 126.9       102.4       126.9 102.4        
Affiliated Companies 47.1       48.0       47.1 48.0        
Accrued Taxes 22.4       22.6       22.4 22.6        
TOTAL CURRENT LIABILITIES 821.6       436.0       821.6 436.0        
Liabilities, Noncurrent                            
Deferred Income Taxes 607.8       642.0       607.8 642.0        
Regulatory Liabilities and Deferred Investment Tax Credits 864.7       853.5       864.7 853.5        
TOTAL NONCURRENT LIABILITIES 2,462.8       2,857.0       2,462.8 2,857.0        
TOTAL LIABILITIES 3,284.4       3,293.0       3,284.4 3,293.0        
Equity [Abstract]                            
Retained Earnings 724.7       691.5       724.7 691.5        
TOTAL LIABILITIES AND EQUITY 4,532.4       4,508.3       4,532.4 4,508.3        
Operating Activites                            
NET INCOME (LOSS) (6.6) 60.4 36.6 (7.2) 0.6 46.2 20.4 4.8 83.2 72.0 100.0      
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:                            
Depreciation and Amortization                 164.0 130.4 130.2      
Deferred Income Taxes                 (31.1) 124.7 82.5      
Allowance for Equity Funds Used During Construction                 (0.4) (0.5) (6.2)      
Change in Other Noncurrent Assets                 0.0 (27.2) (35.9)      
Increase (Decrease) in Other Noncurrent Liabilities                 17.6 4.5 (0.1)      
Accounts Receivable, Net                 5.1 (10.9) (9.0)      
Accounts Payable                 17.7 (10.7) 25.7      
Accrued Taxes, Net                 13.2 0.8 7.4      
Net Cash Flows from (Used for) Operating Activities                 330.5 238.1 217.2      
Investing Activities                            
Net Cash Flows from (Used for) Investing Activities                 (233.0) (261.5) (259.5)      
Net Cash Provided by (Used in) Financing Activities                            
Net Cash Flows from (Used for) Financing Activities                 (97.1) 23.5 42.4      
Net Increase (Decrease) in Cash and Cash Equivalents                 0.4 0.1 0.1      
Cash and Cash Equivalents at Beginning of Period       1.6       1.5 1.6 1.5 1.4      
Cash and Cash Equivalents at End of Period 2.0       1.6       2.0 1.6 1.5      
Organization and Summary of Significant Accounting Policies (Textuals)                            
Issuance of Long-term Debt                 0.0 0.0 274.2      
Repayments of Long-term Debt                 0.5 0.5 275.4      
Net Income (Loss) (6.6) 60.4 36.6 (7.2) 0.6 46.2 20.4 4.8 83.2 72.0 100.0      
Retained Earnings $ 724.7       691.5       $ 724.7 691.5        
Public Service Co Of Oklahoma [Member] | Pension Plans [Member] | Equity [Member]                            
Target Asset Allocations                            
Target Asset Allocation 25.00%               25.00%          
Public Service Co Of Oklahoma [Member] | Pension Plans [Member] | Fixed Income [Member]                            
Target Asset Allocations                            
Target Asset Allocation 59.00%               59.00%          
Public Service Co Of Oklahoma [Member] | Pension Plans [Member] | Other Investments [Member]                            
Target Asset Allocations                            
Target Asset Allocation 15.00%               15.00%          
Public Service Co Of Oklahoma [Member] | Pension Plans [Member] | Cash and Cash Equivalents [Member]                            
Target Asset Allocations                            
Target Asset Allocation 1.00%               1.00%          
Public Service Co Of Oklahoma [Member] | Other Postretirement Benefit Plans [Member] | Equity [Member]                            
Target Asset Allocations                            
Target Asset Allocation 49.00%               49.00%          
Public Service Co Of Oklahoma [Member] | Other Postretirement Benefit Plans [Member] | Fixed Income [Member]                            
Target Asset Allocations                            
Target Asset Allocation 49.00%               49.00%          
Public Service Co Of Oklahoma [Member] | Other Postretirement Benefit Plans [Member] | Cash and Cash Equivalents [Member]                            
Target Asset Allocations                            
Target Asset Allocation 2.00%               2.00%          
Southwestern Electric Power Co [Member]                            
Cash, Cash Equivalents and Restricted Cash                            
Cash and Cash Equivalents at Beginning of Period       1.6       10.3 $ 1.6 10.3 5.2      
Supplemental Income Statement Elements                            
Depreciation and Amortization of Property, Plant and Equipment                 237.0 217.2 196.6      
Amortization of Certain Securitized Assets                 0.0 0.0 0.0      
Amortization of Regulatory Assets and Liabilities                 2.5 0.2 (0.1)      
Utilities Operating Expense, Depreciation and Amortization                 239.5 217.4 196.5      
Cash Paid (Received) for:                            
Cash Paid for Interest, Net of Capitalized Amounts                 125.7 124.4 118.0      
Income Taxes Paid, Net                 18.8 (75.3) (32.0)      
Construction in Progress Expenditures Incurred but Not yet Paid                 42.0 71.2 41.8      
Noncash Investing and Financing Activities:                            
Capital Lease Obligations Incurred                 3.6 3.3 5.9      
Construction Expenditures Included in Current Liabilities as of December 31,                 $ 42.0 $ 71.2 $ 41.8      
Risks and Uncertainties                            
Percentage of Significant Customers Concentration Risk                 10.00% 10.00% 10.00%      
Amounts Attributable to AEP Common Shareholders                            
Net Income (Loss) Attributable to Noncontrolling Interests                 $ 5.0 $ 12.8 $ 4.1      
Revenues                            
TOTAL REVENUES $ 410.1 535.3 457.1 419.4 436.3 517.6 424.7 401.3 1,821.9 1,779.9 1,748.0      
Expenses                            
Depreciation and Amortization                 239.5 217.4 196.5      
TOTAL EXPENSES                 1,544.2 1,475.9 1,430.6      
OPERATING INCOME (LOSS) 38.5 127.1 70.5 41.6 41.1 [2] 136.0 [2] 74.1 [2] 52.8 [2] 277.7 304.0 317.4      
Other Income (Expense)                            
Allowance for Equity Funds Used During Construction                 6.0 2.4 11.0      
Interest Expense                 (127.9) (123.4) (119.7)      
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) AND EQUITY EARNINGS (LOSS)                 169.9 189.4 213.9      
Income Tax Expense (Benefit)                 20.4 48.1 52.1      
NET INCOME (LOSS) 10.5 89.6 38.7 13.4 11.0 84.1 25.1 17.3 152.2 137.5 169.7      
Accounts Receivable:                            
Customers 24.5       70.9       24.5 70.9        
Total Accounts Receivable 72.8       125.6       72.8 125.6        
TOTAL CURRENT ASSETS 414.5       380.4       414.5 380.4        
Property, Plant and Equipment                            
Transmission 1,866.9       1,679.8       1,866.9 1,679.8        
Other Property, Plant and Equipment 762.7       684.1       762.7 684.1        
Construction Work in Progress 199.3       233.2       199.3 233.2        
Total Property, Plant and Equipment 9,680.1       9,317.8       9,680.1 9,317.8        
Accumulated Depreciation and Amortization 2,808.3       2,685.8       2,808.3 2,685.8        
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET 6,871.8       6,632.0       6,871.8 6,632.0        
Other Noncurrent Assets                            
TOTAL OTHER NONCURRENT ASSETS 342.0       330.5       342.0 330.5        
TOTAL ASSETS 7,628.3       7,342.9       7,628.3 7,342.9        
Current Liabilities                            
Accounts Payable 129.1       160.4       129.1 160.4        
Affiliated Companies 64.2       63.7       64.2 63.7        
Accrued Taxes 42.8       39.0       42.8 39.0        
TOTAL CURRENT LIABILITIES 512.9       598.6       512.9 598.6        
Liabilities, Noncurrent                            
Deferred Income Taxes 902.8       917.7       902.8 917.7        
Regulatory Liabilities and Deferred Investment Tax Credits 923.0       896.4       923.0 896.4        
TOTAL NONCURRENT LIABILITIES 4,799.8       4,509.8       4,799.8 4,509.8        
TOTAL LIABILITIES 5,312.7       5,108.4       5,312.7 5,108.4        
Equity [Abstract]                            
Retained Earnings 1,508.4       1,426.6       1,508.4 1,426.6        
TOTAL LIABILITIES AND EQUITY 7,628.3       7,342.9       7,628.3 7,342.9        
Operating Activites                            
NET INCOME (LOSS) 10.5 89.6 38.7 13.4 11.0 84.1 25.1 17.3 152.2 137.5 169.7      
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:                            
Depreciation and Amortization                 239.5 217.4 196.5      
Deferred Income Taxes                 1.2 80.5 162.6      
Allowance for Equity Funds Used During Construction                 (6.0) (2.4) (11.0)      
Change in Other Noncurrent Assets                 (18.8) (9.2) (13.0)      
Increase (Decrease) in Other Noncurrent Liabilities                 46.6 17.0 6.0      
Accounts Receivable, Net                 53.5 (32.9) (5.7)      
Accounts Payable                 0.9 10.5 3.5      
Accrued Taxes, Net                 2.3 45.7 (68.9)      
Net Cash Flows from (Used for) Operating Activities                 504.8 444.7 404.3      
Investing Activities                            
Net Cash Flows from (Used for) Investing Activities                 (528.9) (220.6) (594.0)      
Net Cash Provided by (Used in) Financing Activities                            
Net Cash Flows from (Used for) Financing Activities                 47.0 (232.8) 194.8      
Net Increase (Decrease) in Cash and Cash Equivalents                 22.9 (8.7) 5.1      
Cash and Cash Equivalents at Beginning of Period       1.6       10.3 1.6 10.3 5.2      
Cash and Cash Equivalents at End of Period 24.5       1.6       24.5 1.6 10.3      
Organization and Summary of Significant Accounting Policies (Textuals)                            
Issuance of Long-term Debt                 1,065.7 114.6 406.7      
Repayments of Long-term Debt                 794.5 353.7 3.3      
Income (Loss) from Equity Method Investment                 2.7 (3.8) 7.9      
Net Income (Loss) 10.5 $ 89.6 $ 38.7 13.4 11.0 $ 84.1 $ 25.1 17.3 152.2 137.5 $ 169.7      
Retained Earnings $ 1,508.4       1,426.6       $ 1,508.4 $ 1,426.6        
Southwestern Electric Power Co [Member] | Pension Plans [Member] | Equity [Member]                            
Target Asset Allocations                            
Target Asset Allocation 25.00%               25.00%          
Southwestern Electric Power Co [Member] | Pension Plans [Member] | Fixed Income [Member]                            
Target Asset Allocations                            
Target Asset Allocation 59.00%               59.00%          
Southwestern Electric Power Co [Member] | Pension Plans [Member] | Other Investments [Member]                            
Target Asset Allocations                            
Target Asset Allocation 15.00%               15.00%          
Southwestern Electric Power Co [Member] | Pension Plans [Member] | Cash and Cash Equivalents [Member]                            
Target Asset Allocations                            
Target Asset Allocation 1.00%               1.00%          
Southwestern Electric Power Co [Member] | Other Postretirement Benefit Plans [Member] | Equity [Member]                            
Target Asset Allocations                            
Target Asset Allocation 49.00%               49.00%          
Southwestern Electric Power Co [Member] | Other Postretirement Benefit Plans [Member] | Fixed Income [Member]                            
Target Asset Allocations                            
Target Asset Allocation 49.00%               49.00%          
Southwestern Electric Power Co [Member] | Other Postretirement Benefit Plans [Member] | Cash and Cash Equivalents [Member]                            
Target Asset Allocations                            
Target Asset Allocation 2.00%               2.00%          
Restricted Stock Units and Performance Share Units [Member]                            
Weighted Average Dilutive Effect of:                            
Weighted Average Dilutive Effect of Shares | shares                 1,000,000 800,000 200,000      
Dilutive Securities, Effect on Basic Earnings Per Share | $ / shares                 $ 0 $ (0.01) $ 0      
Revenues [Member] | AEP Texas Inc. [Member]                            
Risks and Uncertainties                            
Percentage of Significant Customers Concentration Risk                 45.00% [9] 35.00% [9],[10] 46.00% [10]      
Revenues [Member] | AEP Transmission Co [Member]                            
Risks and Uncertainties                            
Percentage of Significant Customers Concentration Risk                 77.00% 80.00% 77.00%      
Accounts Receivable [Member] | AEP Texas Inc. [Member]                            
Risks and Uncertainties                            
Percentage of Significant Customers Concentration Risk                 35.00% [9] 31.00% [9],[10] 42.00% [10]      
Accounts Receivable [Member] | AEP Transmission Co [Member]                            
Risks and Uncertainties                            
Percentage of Significant Customers Concentration Risk                 84.00% 85.00% [11] 86.00%      
Previously Reported [Member] | AEP Transmission Co [Member]                            
Cash, Cash Equivalents and Restricted Cash                            
Cash and Cash Equivalents at Beginning of Period       0.0       0.0 $ 0.0 $ 0.0        
Supplemental Income Statement Elements                            
Utilities Operating Expense, Depreciation and Amortization                   97.1        
Cash Paid (Received) for:                            
Cash Paid for Interest, Net of Capitalized Amounts                   61.2        
Construction in Progress Expenditures Incurred but Not yet Paid                   473.7        
Noncash Investing and Financing Activities:                            
Construction Expenditures Included in Current Liabilities as of December 31,                   473.7        
Revenues                            
TOTAL REVENUES                   723.2        
Expenses                            
Depreciation and Amortization                   97.1        
TOTAL EXPENSES                   275.4        
OPERATING INCOME (LOSS)                   447.8        
Other Income (Expense)                            
Allowance for Equity Funds Used During Construction                   52.3        
Interest Expense                   (68.0)        
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) AND EQUITY EARNINGS (LOSS)                   433.3        
Income Tax Expense (Benefit)                   147.2        
NET INCOME (LOSS)                   286.1        
Accounts Receivable:                            
Customers         19.1         19.1        
Total Accounts Receivable         113.6         113.6        
Accrued Tax Benefits         46.6         46.6        
TOTAL CURRENT ASSETS         327.7         327.7        
Property, Plant and Equipment                            
Transmission         5,336.1         5,336.1        
Other Property, Plant and Equipment         131.4         131.4        
Construction Work in Progress         1,312.7         1,312.7        
Total Property, Plant and Equipment         6,780.2         6,780.2        
Accumulated Depreciation and Amortization         170.4         170.4        
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET         6,609.8         6,609.8        
Other Noncurrent Assets                            
Deferred Property Taxes         117.8         117.8        
TOTAL OTHER NONCURRENT ASSETS         130.6         130.6        
TOTAL ASSETS         7,068.1         7,068.1        
Current Liabilities                            
Accounts Payable         473.2         473.2        
Affiliated Companies         52.9         52.9        
Accrued Taxes         225.4         225.4        
TOTAL CURRENT LIABILITIES         836.3         836.3        
Liabilities, Noncurrent                            
Deferred Income Taxes         601.7         601.7        
Regulatory Liabilities and Deferred Investment Tax Credits         493.7         493.7        
TOTAL NONCURRENT LIABILITIES         3,626.5         3,626.5        
TOTAL LIABILITIES         4,462.8         4,462.8        
Equity [Abstract]                            
Retained Earnings         788.7         788.7        
TOTAL MEMBER'S EQUITY         2,605.3         2,605.3        
TOTAL LIABILITIES AND EQUITY         7,068.1         7,068.1        
Operating Activites                            
NET INCOME (LOSS)                   286.1        
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:                            
Depreciation and Amortization                   97.1        
Deferred Income Taxes                   272.8        
Allowance for Equity Funds Used During Construction                   (52.3)        
Amortization of Deferred Property Taxes                   (15.6)        
Change in Other Noncurrent Assets                   9.8        
Increase (Decrease) in Other Noncurrent Liabilities                   27.3        
Accounts Receivable, Net                   (34.5)        
Accounts Payable                   9.8        
Accrued Taxes, Net                   13.0        
Net Cash Flows from (Used for) Operating Activities                   604.8        
Investing Activities                            
Net Cash Flows from (Used for) Investing Activities                   (1,595.6)        
Net Cash Provided by (Used in) Financing Activities                            
Net Cash Flows from (Used for) Financing Activities                   990.8        
Net Increase (Decrease) in Cash and Cash Equivalents                   0.0        
Cash and Cash Equivalents at Beginning of Period       0.0       0.0 0.0 0.0        
Cash and Cash Equivalents at End of Period         0.0         0.0 $ 0.0      
Organization and Summary of Significant Accounting Policies (Textuals)                            
Net Income (Loss)                   286.1        
Retained Earnings         788.7         788.7        
Revision [Member] | AEP Transmission Co [Member]                            
Cash, Cash Equivalents and Restricted Cash                            
Cash and Cash Equivalents at Beginning of Period       0.0       0.0 0.0 0.0        
Supplemental Income Statement Elements                            
Utilities Operating Expense, Depreciation and Amortization                   (1.4)        
Cash Paid (Received) for:                            
Cash Paid for Interest, Net of Capitalized Amounts                   1.2        
Construction in Progress Expenditures Incurred but Not yet Paid                   11.3        
Noncash Investing and Financing Activities:                            
Construction Expenditures Included in Current Liabilities as of December 31,                   11.3        
Revenues                            
TOTAL REVENUES                   (16.3)        
Expenses                            
Depreciation and Amortization                   (1.4)        
TOTAL EXPENSES                   (1.4)        
OPERATING INCOME (LOSS)                   (14.9)        
Other Income (Expense)                            
Allowance for Equity Funds Used During Construction                   (3.3)        
Interest Expense                   (2.2)        
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) AND EQUITY EARNINGS (LOSS)                   (20.4)        
Income Tax Expense (Benefit)                   (5.0)        
NET INCOME (LOSS)                   (15.4)        
Accounts Receivable:                            
Customers         (4.1)         (4.1)        
Total Accounts Receivable         (4.1)         (4.1)        
Accrued Tax Benefits         2.8         2.8        
TOTAL CURRENT ASSETS         (1.3)         (1.3)        
Property, Plant and Equipment                            
Transmission         (16.4)         (16.4)        
Other Property, Plant and Equipment         (4.6)         (4.6)        
Construction Work in Progress         11.3         11.3        
Total Property, Plant and Equipment         (9.7)         (9.7)        
Accumulated Depreciation and Amortization         (17.8)         (17.8)        
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET         8.1         8.1        
Other Noncurrent Assets                            
Deferred Property Taxes         7.2         7.2        
TOTAL OTHER NONCURRENT ASSETS         7.2         7.2        
TOTAL ASSETS         14.0         14.0        
Current Liabilities                            
Accounts Payable         11.3         11.3        
Affiliated Companies         13.2         13.2        
Accrued Taxes         6.1         6.1        
TOTAL CURRENT LIABILITIES         30.6         30.6        
Liabilities, Noncurrent                            
Deferred Income Taxes         (1.3)         (1.3)        
Regulatory Liabilities and Deferred Investment Tax Credits         0.1         0.1        
TOTAL NONCURRENT LIABILITIES         (1.2)         (1.2)        
TOTAL LIABILITIES         29.4         29.4        
Equity [Abstract]                            
Retained Earnings         (15.4)         (15.4)        
TOTAL MEMBER'S EQUITY         (15.4)         (15.4)        
TOTAL LIABILITIES AND EQUITY         14.0         14.0        
Operating Activites                            
NET INCOME (LOSS)                   (15.4)        
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:                            
Depreciation and Amortization                   (1.4)        
Deferred Income Taxes                   (1.3)        
Allowance for Equity Funds Used During Construction                   3.3        
Amortization of Deferred Property Taxes                   (7.2)        
Change in Other Noncurrent Assets                   1.2        
Increase (Decrease) in Other Noncurrent Liabilities                   0.2        
Accounts Receivable, Net                   4.1        
Accounts Payable                   13.2        
Accrued Taxes, Net                   3.3        
Net Cash Flows from (Used for) Operating Activities                   0.0        
Investing Activities                            
Net Cash Flows from (Used for) Investing Activities                   0.0        
Net Cash Provided by (Used in) Financing Activities                            
Net Cash Flows from (Used for) Financing Activities                   0.0        
Net Increase (Decrease) in Cash and Cash Equivalents                   0.0        
Cash and Cash Equivalents at Beginning of Period       $ 0.0       $ 0.0 $ 0.0 0.0        
Cash and Cash Equivalents at End of Period         0.0         $ 0.0 $ 0.0      
Organization and Summary of Significant Accounting Policies (Textuals)                            
Error Corrections and Prior Period Adjustments, Description                   The $(20) million adjustment to pretax income for the year ended December 31, 2017 includes adjustments of $(12) million relating to 2016 and earlier periods. The effect of recording this adjustment of $(12) million in 2017 is not material to AEPTCo’s financial statements for 2017 or any earlier period   AEPTCo recorded a pretax out of period correction of an error of approximately $17 million related to revenue recorded from 2013 through March 31, 2018 in the second quarter of 2018 The impact of this misstatement reduced AEPTCo’s pretax income by approximately $7 million on a cumulative basis for the period 2011 through June 30, 2018  
Net Income (Loss)                   $ (15.4)        
Retained Earnings         $ (15.4)         $ (15.4)        
[1] Quarterly Earnings per Share amounts are intended to be stand-alone calculations and are not always additive to full-year amount due to rounding.
[2] Amounts reflect the adoption of ASU 2017-07 “Compensation - Retirement Benefits”. See Note 2 - New Accounting Pronouncements for additional information.
[3] (a)Reflects the revisions made to AEPTCo’s previously issued financial statements. For additional details on the revisions to AEPTCo’s financial statements, see “Revisions to Previously Issued Financial Statements” below.
[4] The amounts presented reflect the revisions made to AEPTCo’s previously issued financial statements. See the “Revisions to Previously Issued Financial Statements” section of Note 1 for additional information.
[5] The amounts presented for the Quarterly Periods Ended March 31, 2018 and June 30, 2018 reflect the revisions made to AEPTCo’s previously issued financial statements. See the “Revisions to Previously issued Financial Statement” section of Note 1.
[6] The amount presented reflects the revisions made to AEPTCo’s previously issued financial statements. See the “Revisions to Previously Issued Financial Statements” section of Note 1 for additional information.
[7] The amounts presented reflect the revisions made to AEPTCo’s previously issued financial statements. See “Revisions to Previously Issued Financial Statements” section of Note 1 for additional information.
[8] The amounts presented reflect the revisions made to AEPTCo’s previously issued financial statements. See the “Revisions to Previously Issued Financial Statements” section of Note 1 for additional information.
[9] Just Energy did not meet the Total Revenue threshold of 10% in order to be considered a significant customer.
[10] TXU Energy did not meet the Total Revenue threshold of 10% in order to be considered a significant customer.
[11] Reflects the revisions made to AEPTCo’s previously issued financial statements. See the “Revisions to Previously Issued Financial Statements” section of Note 1 for additional information.