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Financing Activities (Details) - USD ($)
$ in Millions
1 Months Ended 12 Months Ended
Feb. 21, 2019
Jan. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Shares of Company          
Beginning Balance, Shares   513,450,036 512,210,644 512,048,520 511,389,173
Issued     1,239,392 162,124 659,347
Ending Balance, Shares     513,450,036 512,210,644 512,048,520
Treasury Stock, Shares, Beginning Balance   20,204,160 20,205,046 20,336,592 20,336,592
Partners' Capital Account, Units, Treasury Units Reissued [1]     (886) (131,546)  
Treasury Stock, Shares, Ending Balance     20,204,160 20,205,046 20,336,592
Long-term Debt          
Senior Unsecured Notes     $ 18,903.3 $ 16,478.3  
Pollution Control Bonds [2]     1,643.8 1,621.7  
Notes Payable [3]     204.7 260.8  
Securitization Bonds     1,111.4 1,416.5  
Spent Nuclear Fuel Obligation [4]     273.6 268.6  
Other Long-term Debt     1,209.9 1,127.4  
Total Long-term Debt Outstanding     23,346.7 21,173.3  
Outstanding Long-term Debt          
Principal Amount, 2019     1,698.5    
Principal Amount, 2020     1,508.3    
Principal Amount, 2021     1,961.5    
Principal Amount, 2022     1,668.4    
Principal Amount, 2023     539.6    
Principal Amount, After 2023     16,150.9    
Principal Amount, Total     23,527.2    
Unamortized Discount, Net and Debt Issuance Costs     (180.5)    
Total Long-term Debt Outstanding     23,346.7 21,173.3  
Short-term Debt          
Securitized Debt for Receivables [5]     750.0 718.0  
Commercial Paper     1,160.0 898.6  
Notes Payable     0.0 22.0  
Total Short-term Debt     $ 1,910.0 $ 1,638.6  
Securitized Debt for Receivables [5],[6]     2.16% 1.22%  
Comparative Accounts Receivable Information          
Effective Interest Rates on Securitization of Accounts Receivable     2.16% 1.22% 0.70%
Net Uncollectible Accounts Receivable Written Off     $ 27.6 $ 23.4 $ 23.7
Customer Accounts Receivable Managed Portfolio          
Accounts Receivable Retained Interest and Pledged as Collateral Less Uncollectible Accounts     972.5 925.5  
Total Principal Outstanding     750.0 718.0  
Delinquent Securitized Accounts Receivable     50.3 41.1  
Bad Debt Reserves Related to Securitized Sale of Accounts Receivable     27.5 28.7  
Unbilled Receivables Related to Securitization, Sale of Accounts Receivable     281.4 303.2  
Fees Paid to AEP Credit for Customer Accounts Receivable Sold          
Revenue from Contracts with Customers     16,195.7 15,424.9 16,380.1
Financing Activities (Textuals)          
Repayments of Long-term Debt     2,782.0 3,087.9 1,794.9
Proceeds from Issuance of Long-term Debt     4,945.7 3,854.1 2,594.9
Total Commitment From Bank Conduits To Finance Receivables     750.0    
Reaquired Pollution Control Bonds Held by Trustees     $ 574.0    
Maximum Percentage Debt to Capitalization     67.50%    
Restricted Net Assets     $ 12,400.0    
Retained Earnings Available to Pay Dividends     7,700.0    
Dividend Restrictions [7]     1,591.4    
Dividends Paid on Common Stock     (1,255.5) $ (1,191.9) (1,121.0)
Credit Facilities, Total     4,000.0    
Maximum Amount of Commercial Paper Outstanding     $ 2,300.0    
Weighted Average Interest Rate of Commercial Paper Outstanding During Year     2.332%    
Commercial Paper [Member]          
Short-term Debt          
Debt, Weighted Average Interest Rate [6]     2.9649% 1.85%  
Loans Payable [Member]          
Short-term Debt          
Debt, Weighted Average Interest Rate [6]     0.00% 2.92%  
AEP Texas Inc. [Member]          
Long-term Debt          
Senior Unsecured Notes     $ 2,398.4 $ 1,932.2  
Pollution Control Bonds     490.9 490.5  
Securitization Bonds     791.2 1,026.1  
Other Long-term Debt     200.8 200.5  
Total Long-term Debt Outstanding     3,881.3 3,649.3  
Outstanding Long-term Debt          
Principal Amount, 2019     501.1    
Principal Amount, 2020     377.7    
Principal Amount, 2021     66.2    
Principal Amount, 2022     493.0    
Principal Amount, 2023     195.0    
Principal Amount, After 2023     2,275.5    
Principal Amount, Total     3,908.5    
Unamortized Discount, Net and Debt Issuance Costs     (27.2)    
Total Long-term Debt Outstanding     3,881.3 3,649.3  
Fees Paid to AEP Credit for Customer Accounts Receivable Sold          
Revenue from Contracts with Customers     1,493.0    
Financing Activities (Textuals)          
Repayments of Long-term Debt     266.1 323.1 428.7
Proceeds from Issuance of Long-term Debt     $ 494.0 749.6 199.2
Maximum Percentage Debt to Capitalization     67.50%    
Dividend Restrictions     $ 353.7    
Dividends Paid on Common Stock     0.0 0.0 $ (34.0)
AEP Texas Inc. [Member] | Utility [Member]          
Money Pool Participants' Money Pool Activity and Authorized Borrowing Limits          
Maximum Borrowings from Money Pool     390.6 296.0  
Maximum Loans to Money Pool     106.9 451.7  
Average Borrowings from Money Pool     176.0 194.8  
Average Loans to Money Pool     47.1 264.6  
Net Loans (Borrowings) to/from Money Pool     (216.0) 103.5  
Authorized Short Term Borrowing Limit     $ 500.0 $ 400.0  
Maximum and Minimum Interest Rates          
Maximum Interest Rate     2.97% 1.85% 1.02%
Minimum Interest Rate     1.81% 0.92% 0.69%
Average Interest Rates for Funds Borrowed from and Loaned to Money Pool          
Average Interest Rate For Funds Borrowed     2.26% 1.29% 0.88%
Average Interest Rate For Funds Loaned     2.29% 1.26% 0.72%
AEP Texas Inc. [Member] | Nonutility [Member]          
Maximum Interest Rate for Funds Borrowed     0.00% 0.00% 1.11%
Minimum Interest Rate For Funds Borrowed     0.00% 0.00% 0.97%
Maximum Interest Rate For Funds Loaned     2.97% 1.85% 1.02%
Minimum Interest Rate for Funds Loaned     1.83% 0.00% 0.75%
Money Pool Participants' Money Pool Activity and Authorized Borrowing Limits          
Maximum Loans to Money Pool     $ 8.4 $ 8.6  
Average Loans to Money Pool     8.1 8.3  
Net Loans (Borrowings) to/from Money Pool     $ 8.0 $ 8.4  
Average Interest Rates for Funds Borrowed from and Loaned to Money Pool          
Average Interest Rate For Funds Borrowed     0.00% 0.00% 1.00%
Average Interest Rate For Funds Loaned     2.36% 1.32% 0.86%
AEP Texas Inc. [Member] | Direct Borrowing [Member]          
Maximum Interest Rate for Funds Borrowed     0.00% 0.00% 0.98%
Minimum Interest Rate For Funds Borrowed     0.00% 0.00% 0.69%
Maximum Interest Rate For Funds Loaned     0.00% 0.00% 1.02%
Minimum Interest Rate for Funds Loaned     0.00% 0.00% 0.99%
Average Interest Rates for Funds Borrowed from and Loaned to Money Pool          
Average Interest Rate For Funds Borrowed     0.00% 0.00% 0.83%
Average Interest Rate For Funds Loaned     0.00% 0.00% 1.00%
AEP Transmission Co [Member]          
Long-term Debt          
Senior Unsecured Notes     $ 2,823.0 $ 2,550.4  
Total Long-term Debt Outstanding     2,823.0 2,550.4 [8]  
Outstanding Long-term Debt          
Principal Amount, 2019     85.0    
Principal Amount, 2020     0.0    
Principal Amount, 2021     50.0    
Principal Amount, 2022     104.0    
Principal Amount, 2023     60.0    
Principal Amount, After 2023     2,551.0    
Principal Amount, Total     2,850.0    
Unamortized Discount, Net and Debt Issuance Costs     (27.0)    
Total Long-term Debt Outstanding     2,823.0 2,550.4 [8]  
Fees Paid to AEP Credit for Customer Accounts Receivable Sold          
Revenue from Contracts with Customers     832.0    
Financing Activities (Textuals)          
Repayments of Long-term Debt     50.0 0.0 $ 300.0
Proceeds from Issuance of Long-term Debt     321.0 617.6 $ 686.9
Sub-Limit of Secured Debt     $ 50.0    
Maximum Percentage of Consolidated Tangible Net Assets     10.00%    
Tangible Capital to Tangible Assets     0.60%    
Maximum Percentage Debt to Capitalization     67.50%    
Dividend Restrictions     $ 0.0    
AEP Transmission Co [Member] | Utility [Member]          
Money Pool Participants' Money Pool Activity and Authorized Borrowing Limits          
Maximum Borrowings from Money Pool     371.3 467.2  
Maximum Loans to Money Pool     276.4 268.0  
Average Borrowings from Money Pool     177.9 180.5  
Average Loans to Money Pool     58.4 119.8  
Net Loans (Borrowings) to/from Money Pool     35.8 109.2  
Authorized Short Term Borrowing Limit [9]     $ 795.0 $ 795.0  
Maximum and Minimum Interest Rates          
Maximum Interest Rate     2.97% 1.85% 1.02%
Minimum Interest Rate     1.81% 0.92% 0.69%
Average Interest Rates for Funds Borrowed from and Loaned to Money Pool          
Average Interest Rate For Funds Borrowed     2.27% 1.36% 0.85%
Average Interest Rate For Funds Loaned     2.10% 1.27% 0.83%
AEP Transmission Co [Member] | Direct Borrowing [Member]          
Maximum Interest Rate for Funds Borrowed     2.97% 1.85% 1.02%
Minimum Interest Rate For Funds Borrowed     1.76% 0.92% 0.69%
Maximum Interest Rate For Funds Loaned     2.97% 1.85% 1.02%
Minimum Interest Rate for Funds Loaned     1.76% 0.92% 0.69%
Money Pool Participants' Money Pool Activity and Authorized Borrowing Limits          
Maximum Borrowings from Money Pool     $ 1.2 $ 4.1  
Maximum Loans to Money Pool     104.7 151.9  
Average Borrowings from Money Pool     1.1 1.1  
Average Loans to Money Pool     49.8 39.3  
Borrowings from Parent     1.2 1.1  
Loans to Parent     16.9 22.5  
Authorized Short Term Borrowing Limit [10]     $ 75.0 $ 75.0  
Average Interest Rates for Funds Borrowed from and Loaned to Money Pool          
Average Interest Rate For Funds Borrowed     2.36% 1.33% 0.83%
Average Interest Rate For Funds Loaned     2.36% 1.36% 0.87%
Appalachian Power Co [Member]          
Long-term Debt          
Senior Unsecured Notes     $ 3,047.3 $ 3,045.1  
Pollution Control Bonds [2]     616.0 512.2  
Securitization Bonds     272.3 295.9  
Other Long-term Debt     127.0 126.9  
Total Long-term Debt Outstanding     4,062.6 3,980.1  
Outstanding Long-term Debt          
Principal Amount, 2019     430.7    
Principal Amount, 2020     90.3    
Principal Amount, 2021     393.0    
Principal Amount, 2022     230.4    
Principal Amount, 2023     26.6    
Principal Amount, After 2023     2,924.4    
Principal Amount, Total     4,095.4    
Unamortized Discount, Net and Debt Issuance Costs     (32.8)    
Total Long-term Debt Outstanding     4,062.6 3,980.1  
Accounts Receivable and Accrued Unbilled Revenue          
Accounts Receivable and Accrued Unbilled Revenues     133.3 136.2  
Fees Paid to AEP Credit for Customer Accounts Receivable Sold          
Revenue from Contracts with Customers     2,993.2    
Proceeds on Sale of Receivables to AEP Credit          
Proceeds from Sale of Receivables to AEP Credit     1,421.0 1,372.8 $ 1,412.5
Financing Activities (Textuals)          
Repayments of Long-term Debt     124.0 377.9 213.6
Proceeds from Issuance of Long-term Debt     $ 203.2 320.9 $ 314.0
Maximum Percentage Debt to Capitalization     67.50%    
Dividend Restrictions     $ 17.6    
Appalachian Power Co [Member] | Utility [Member]          
Money Pool Participants' Money Pool Activity and Authorized Borrowing Limits          
Maximum Borrowings from Money Pool     295.5 231.5  
Maximum Loans to Money Pool     23.7 160.7  
Average Borrowings from Money Pool     175.3 144.3  
Average Loans to Money Pool     23.3 30.0  
Net Loans (Borrowings) to/from Money Pool     (182.6) (162.5)  
Authorized Short Term Borrowing Limit     $ 600.0 $ 600.0  
Maximum and Minimum Interest Rates          
Maximum Interest Rate     2.97% 1.85% 1.02%
Minimum Interest Rate     1.81% 0.92% 0.69%
Average Interest Rates for Funds Borrowed from and Loaned to Money Pool          
Average Interest Rate For Funds Borrowed     2.26% 1.28% 0.80%
Average Interest Rate For Funds Loaned     2.21% 1.29% 0.82%
Indiana Michigan Power Co [Member]          
Long-term Debt          
Senior Unsecured Notes     $ 2,149.0 $ 1,809.0  
Pollution Control Bonds [2]     264.5 264.6  
Notes Payable [3]     135.8 188.6  
Spent Nuclear Fuel Obligation [4]     273.6 268.6  
Other Long-term Debt     212.5 214.3  
Total Long-term Debt Outstanding     3,035.4 2,745.1  
Outstanding Long-term Debt          
Principal Amount, 2019     155.4    
Principal Amount, 2020     41.6    
Principal Amount, 2021     256.4    
Principal Amount, 2022     7.0    
Principal Amount, 2023     252.4    
Principal Amount, After 2023     2,351.5    
Principal Amount, Total     3,064.3    
Unamortized Discount, Net and Debt Issuance Costs     (28.9)    
Total Long-term Debt Outstanding     3,035.4 2,745.1  
Accounts Receivable and Accrued Unbilled Revenue          
Accounts Receivable and Accrued Unbilled Revenues     152.9 136.5  
Fees Paid to AEP Credit for Customer Accounts Receivable Sold          
Revenue from Contracts with Customers     2,381.0    
Proceeds on Sale of Receivables to AEP Credit          
Proceeds from Sale of Receivables to AEP Credit     1,843.0 1,612.9 $ 1,596.2
Financing Activities (Textuals)          
Repayments of Long-term Debt     884.9 260.7 100.2
Proceeds from Issuance of Long-term Debt     $ 1,168.1 530.1 $ 569.4
Maximum Percentage Debt to Capitalization     67.50%    
Dividend Restrictions     $ 454.1    
Indiana Michigan Power Co [Member] | Utility [Member]          
Money Pool Participants' Money Pool Activity and Authorized Borrowing Limits          
Maximum Borrowings from Money Pool     322.1 367.4  
Maximum Loans to Money Pool     657.8 12.6  
Average Borrowings from Money Pool     255.5 204.9  
Average Loans to Money Pool     110.7 12.6  
Net Loans (Borrowings) to/from Money Pool     11.6 (199.2)  
Authorized Short Term Borrowing Limit     $ 500.0 $ 500.0  
Maximum and Minimum Interest Rates          
Maximum Interest Rate     2.97% 1.85% 1.02%
Minimum Interest Rate     1.81% 0.92% 0.69%
Average Interest Rates for Funds Borrowed from and Loaned to Money Pool          
Average Interest Rate For Funds Borrowed     2.16% 1.27% 0.80%
Average Interest Rate For Funds Loaned     2.08% 1.29% 0.80%
Ohio Power Co [Member]          
Long-term Debt          
Senior Unsecured Notes     $ 1,635.5 $ 1,591.4  
Pollution Control Bonds     32.3 32.3  
Securitization Bonds     47.8 94.5  
Other Long-term Debt     1.0 1.1  
Total Long-term Debt Outstanding     1,716.6 1,719.3  
Outstanding Long-term Debt          
Principal Amount, 2019     47.9    
Principal Amount, 2020     0.1    
Principal Amount, 2021     500.1    
Principal Amount, 2022     0.1    
Principal Amount, 2023     0.1    
Principal Amount, After 2023     1,182.8    
Principal Amount, Total     1,731.1    
Unamortized Discount, Net and Debt Issuance Costs     (14.5)    
Total Long-term Debt Outstanding     1,716.6 1,719.3  
Accounts Receivable and Accrued Unbilled Revenue          
Accounts Receivable and Accrued Unbilled Revenues     395.2 367.4  
Fees Paid to AEP Credit for Customer Accounts Receivable Sold          
Revenue from Contracts with Customers     3,079.9    
Proceeds on Sale of Receivables to AEP Credit          
Proceeds from Sale of Receivables to AEP Credit     2,674.5 2,339.0 $ 2,633.0
Financing Activities (Textuals)          
Repayments of Long-term Debt     397.1 46.4 395.9
Proceeds from Issuance of Long-term Debt     392.8 0.0 $ 0.0
Reaquired Pollution Control Bonds Held by Trustees     345.0    
Dividend Restrictions     0.0    
Ohio Power Co [Member] | Utility [Member]          
Money Pool Participants' Money Pool Activity and Authorized Borrowing Limits          
Maximum Borrowings from Money Pool     270.8 280.6  
Maximum Loans to Money Pool     225.0 56.2  
Average Borrowings from Money Pool     167.8 137.0  
Average Loans to Money Pool     189.4 27.9  
Net Loans (Borrowings) to/from Money Pool     (114.1) (87.8)  
Authorized Short Term Borrowing Limit     $ 500.0 $ 400.0  
Maximum and Minimum Interest Rates          
Maximum Interest Rate     2.97% 1.85% 1.02%
Minimum Interest Rate     1.81% 0.92% 0.69%
Average Interest Rates for Funds Borrowed from and Loaned to Money Pool          
Average Interest Rate For Funds Borrowed     2.18% 1.37% 0.85%
Average Interest Rate For Funds Loaned     2.47% 0.98% 0.74%
Public Service Co Of Oklahoma [Member]          
Shares of Company          
Beginning Balance, Shares   10,482,000 10,482,000    
Ending Balance, Shares     10,482,000 10,482,000  
Long-term Debt          
Senior Unsecured Notes     $ 1,144.9 $ 1,144.1  
Pollution Control Bonds     12.6 12.6  
Other Long-term Debt     129.5 129.8  
Total Long-term Debt Outstanding     1,287.0 1,286.5  
Outstanding Long-term Debt          
Principal Amount, 2019     375.5    
Principal Amount, 2020     13.2    
Principal Amount, 2021     250.5    
Principal Amount, 2022     0.5    
Principal Amount, 2023     0.5    
Principal Amount, After 2023     652.0    
Principal Amount, Total     1,292.2    
Unamortized Discount, Net and Debt Issuance Costs     (5.2)    
Total Long-term Debt Outstanding     1,287.0 1,286.5  
Accounts Receivable and Accrued Unbilled Revenue          
Accounts Receivable and Accrued Unbilled Revenues     109.7 115.1  
Fees Paid to AEP Credit for Customer Accounts Receivable Sold          
Revenue from Contracts with Customers     1,536.4    
Proceeds on Sale of Receivables to AEP Credit          
Proceeds from Sale of Receivables to AEP Credit     1,484.6 1,337.0 $ 1,269.3
Financing Activities (Textuals)          
Repayments of Long-term Debt     0.5 0.5 275.4
Proceeds from Issuance of Long-term Debt     $ 0.0 0.0 $ 274.2
Maximum Percentage Debt to Capitalization     67.50%    
Dividend Restrictions     $ 152.7    
Public Service Co Of Oklahoma [Member] | Utility [Member]          
Money Pool Participants' Money Pool Activity and Authorized Borrowing Limits          
Maximum Borrowings from Money Pool     193.7 185.2  
Maximum Loans to Money Pool     31.8 0.0  
Average Borrowings from Money Pool     104.5 119.3  
Average Loans to Money Pool     12.9 0.0  
Net Loans (Borrowings) to/from Money Pool     (105.5) (149.6)  
Authorized Short Term Borrowing Limit     $ 300.0 $ 300.0  
Maximum and Minimum Interest Rates          
Maximum Interest Rate     2.97% 1.85% 1.02%
Minimum Interest Rate     1.81% 0.92% 0.69%
Average Interest Rates for Funds Borrowed from and Loaned to Money Pool          
Average Interest Rate For Funds Borrowed     2.27% 1.32% 0.96%
Average Interest Rate For Funds Loaned     1.98% 0.00% 0.83%
Southwestern Electric Power Co [Member]          
Long-term Debt          
Senior Unsecured Notes     $ 2,427.0 $ 2,110.7  
Pollution Control Bonds     53.5 135.1  
Notes Payable [3]     68.9 72.1  
Other Long-term Debt     164.0 124.0  
Total Long-term Debt Outstanding     2,713.4 2,441.9  
Outstanding Long-term Debt          
Principal Amount, 2019     59.7    
Principal Amount, 2020     121.2    
Principal Amount, 2021     6.2    
Principal Amount, 2022     281.2    
Principal Amount, 2023     6.2    
Principal Amount, After 2023     2,262.9    
Principal Amount, Total     2,737.4    
Unamortized Discount, Net and Debt Issuance Costs     (24.0)    
Total Long-term Debt Outstanding     2,713.4 2,441.9  
Short-term Debt          
Notes Payable     0.0 22.0  
Accounts Receivable and Accrued Unbilled Revenue          
Accounts Receivable and Accrued Unbilled Revenues     150.3 138.2  
Fees Paid to AEP Credit for Customer Accounts Receivable Sold          
Revenue from Contracts with Customers     1,817.0    
Proceeds on Sale of Receivables to AEP Credit          
Proceeds from Sale of Receivables to AEP Credit     1,736.1 1,563.4 $ 1,531.7
Financing Activities (Textuals)          
Repayments of Long-term Debt     794.5 353.7 3.3
Proceeds from Issuance of Long-term Debt     $ 1,065.7 114.6 406.7
Maximum Percentage Debt to Capitalization     67.50%    
Dividend Restrictions     $ 526.4    
Dividends Paid on Common Stock     (4.3) (13.6) $ (4.2)
Southwestern Electric Power Co [Member] | Utility [Member]          
Money Pool Participants' Money Pool Activity and Authorized Borrowing Limits          
Maximum Borrowings from Money Pool     200.1 187.5  
Maximum Loans to Money Pool     533.7 178.6  
Average Borrowings from Money Pool     143.2 95.5  
Average Loans to Money Pool     268.1 169.5  
Net Loans (Borrowings) to/from Money Pool     81.4 (118.7)  
Authorized Short Term Borrowing Limit     $ 350.0 $ 350.0  
Maximum and Minimum Interest Rates          
Maximum Interest Rate     2.97% 1.85% 1.02%
Minimum Interest Rate     1.81% 0.92% 0.69%
Average Interest Rates for Funds Borrowed from and Loaned to Money Pool          
Average Interest Rate For Funds Borrowed     2.31% 1.28% 0.79%
Average Interest Rate For Funds Loaned     2.00% 0.98% 0.90%
Southwestern Electric Power Co [Member] | Nonutility [Member]          
Maximum Interest Rate for Funds Borrowed     0.00% 0.00% 0.00%
Minimum Interest Rate For Funds Borrowed     0.00% 0.00% 0.00%
Maximum Interest Rate For Funds Loaned     2.97% 1.85% 1.02%
Minimum Interest Rate for Funds Loaned     1.83% 0.00% 0.69%
Money Pool Participants' Money Pool Activity and Authorized Borrowing Limits          
Maximum Loans to Money Pool     $ 2.0 $ 2.0  
Average Loans to Money Pool     2.0 2.0  
Net Loans (Borrowings) to/from Money Pool     $ 2.0 $ 2.0  
Average Interest Rates for Funds Borrowed from and Loaned to Money Pool          
Average Interest Rate For Funds Borrowed     0.00% 0.00% 0.00%
Average Interest Rate For Funds Loaned     2.36% 1.32% 0.82%
Southwestern Electric Power Co [Member] | Loans Payable [Member]          
Short-term Debt          
Debt, Weighted Average Interest Rate [6]     0.00% 2.92%  
Senior Notes [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2018    
Maturity Date High     2048    
Weighted Average Interest Rate     4.36%    
Senior Notes [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     2.15% 2.15%  
Senior Notes [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     8.13% 8.13%  
Senior Notes [Member] | AEP Texas Inc. [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2018    
Maturity Date High     2047    
Weighted Average Interest Rate     4.06%    
Senior Notes [Member] | AEP Texas Inc. [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     2.40% 2.40%  
Senior Notes [Member] | AEP Texas Inc. [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     6.76% 6.76%  
Senior Notes [Member] | AEP Transmission Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2018    
Maturity Date High     2048    
Weighted Average Interest Rate     3.92%    
Senior Notes [Member] | AEP Transmission Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     2.68% 2.68%  
Senior Notes [Member] | AEP Transmission Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     5.52% 5.52%  
Senior Notes [Member] | Appalachian Power Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2021    
Maturity Date High     2045    
Weighted Average Interest Rate     5.20%    
Senior Notes [Member] | Appalachian Power Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     3.30% 3.30%  
Senior Notes [Member] | Appalachian Power Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     7.00% 7.00%  
Senior Notes [Member] | Indiana Michigan Power Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2019    
Maturity Date High     2048    
Weighted Average Interest Rate     4.38%    
Senior Notes [Member] | Indiana Michigan Power Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     3.20% 3.20%  
Senior Notes [Member] | Indiana Michigan Power Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     6.05% 7.00%  
Senior Notes [Member] | Ohio Power Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2018    
Maturity Date High     2048    
Weighted Average Interest Rate     5.52%    
Senior Notes [Member] | Ohio Power Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     4.15% 5.375%  
Senior Notes [Member] | Ohio Power Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     6.60% 6.60%  
Senior Notes [Member] | Public Service Co Of Oklahoma [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2019    
Maturity Date High     2046    
Weighted Average Interest Rate     4.80%    
Senior Notes [Member] | Public Service Co Of Oklahoma [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     3.05% 3.05%  
Senior Notes [Member] | Public Service Co Of Oklahoma [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     6.625% 6.625%  
Senior Notes [Member] | Southwestern Electric Power Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2018    
Maturity Date High     2048    
Weighted Average Interest Rate     4.04%    
Senior Notes [Member] | Southwestern Electric Power Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     2.75% 2.75%  
Senior Notes [Member] | Southwestern Electric Power Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     6.20% 6.45%  
Pollution Control Bonds [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low [11]     2018    
Maturity Date High [11]     2038    
Weighted Average Interest Rate     3.14%    
Pollution Control Bonds [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     1.60% 1.54%  
Pollution Control Bonds [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     6.30% 6.30%  
Pollution Control Bonds [Member] | AEP Texas Inc. [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2020    
Maturity Date High     2030    
Weighted Average Interest Rate     4.39%    
Pollution Control Bonds [Member] | AEP Texas Inc. [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     1.75% 1.75%  
Pollution Control Bonds [Member] | AEP Texas Inc. [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     6.30% 6.30%  
Pollution Control Bonds [Member] | Appalachian Power Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low [11]     2018    
Maturity Date High [11]     2038    
Weighted Average Interest Rate     2.64%    
Pollution Control Bonds [Member] | Appalachian Power Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     1.70% 1.625%  
Pollution Control Bonds [Member] | Appalachian Power Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     5.38% 5.38%  
Pollution Control Bonds [Member] | Indiana Michigan Power Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low [11]     2018    
Maturity Date High [11]     2025    
Weighted Average Interest Rate     2.49%    
Pollution Control Bonds [Member] | Indiana Michigan Power Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     1.81% 1.75%  
Pollution Control Bonds [Member] | Indiana Michigan Power Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     3.05% 2.75%  
Pollution Control Bonds [Member] | Ohio Power Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2038    
Maturity Date High     2038    
Weighted Average Interest Rate     5.80%    
Pollution Control Bonds [Member] | Ohio Power Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     5.80% 5.80%  
Pollution Control Bonds [Member] | Ohio Power Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     5.80% 5.80%  
Pollution Control Bonds [Member] | Public Service Co Of Oklahoma [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2020    
Maturity Date High     2020    
Weighted Average Interest Rate     4.45%    
Pollution Control Bonds [Member] | Public Service Co Of Oklahoma [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     4.45% 4.45%  
Pollution Control Bonds [Member] | Public Service Co Of Oklahoma [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     4.45% 4.45%  
Pollution Control Bonds [Member] | Southwestern Electric Power Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2018    
Maturity Date High     2019    
Weighted Average Interest Rate     1.60%    
Pollution Control Bonds [Member] | Southwestern Electric Power Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     1.60% 1.60%  
Pollution Control Bonds [Member] | Southwestern Electric Power Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     1.60% 4.95%  
Pollution Control Bonds [Member] | Southwestern Electric Power Co [Member] | Subsequent Event [Member]          
Financing Activities (Textuals)          
Repayments of Long-term Debt   $ 54.0      
Debt Instrument, Interest Rate, Stated Percentage   1.60%      
Due Date   2019      
Notes Payable, Other Payables [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2019    
Maturity Date High     2032    
Weighted Average Interest Rate     3.95%    
Notes Payable, Other Payables [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     3.20% 2.03%  
Notes Payable, Other Payables [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     6.37% 6.37%  
Notes Payable, Other Payables [Member] | Indiana Michigan Power Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2019    
Maturity Date High     2022    
Weighted Average Interest Rate     3.30%    
Notes Payable, Other Payables [Member] | Indiana Michigan Power Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     3.20% 2.03%  
Notes Payable, Other Payables [Member] | Indiana Michigan Power Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     3.38% 2.19%  
Notes Payable, Other Payables [Member] | Indiana Michigan Power Co [Member] | Subsequent Event [Member]          
Financing Activities (Textuals)          
Repayments of Long-term Debt $ 2.0 $ 15.0      
Notes Payable, Other Payables [Member] | Southwestern Electric Power Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2024    
Maturity Date High     2032    
Weighted Average Interest Rate     5.23%    
Notes Payable, Other Payables [Member] | Southwestern Electric Power Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     4.58% 4.58%  
Notes Payable, Other Payables [Member] | Southwestern Electric Power Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     6.37% 6.37%  
Securitization Bonds [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low [12]     2018    
Maturity Date High [12]     2028    
Weighted Average Interest Rate     3.65%    
Securitization Bonds [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     1.98% 1.98%  
Securitization Bonds [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     5.31% 5.31%  
Securitization Bonds [Member] | AEP Texas Inc. [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low [12]     2018    
Maturity Date High [12]     2024    
Weighted Average Interest Rate     3.95%    
Securitization Bonds [Member] | AEP Texas Inc. [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     1.98% 1.98%  
Securitization Bonds [Member] | AEP Texas Inc. [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     5.31% 5.31%  
Securitization Bonds [Member] | AEP Texas Inc. [Member] | Subsequent Event [Member]          
Financing Activities (Textuals)          
Repayments of Long-term Debt   104.0      
Securitization Bonds [Member] | Appalachian Power Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low [12]     2023    
Maturity Date High [12]     2028    
Weighted Average Interest Rate     3.06%    
Securitization Bonds [Member] | Appalachian Power Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     2.008% 2.008%  
Securitization Bonds [Member] | Appalachian Power Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     3.772% 3.772%  
Securitization Bonds [Member] | Appalachian Power Co [Member] | Subsequent Event [Member]          
Financing Activities (Textuals)          
Repayments of Long-term Debt 12.0        
Securitization Bonds [Member] | Ohio Power Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low [12]     2019    
Maturity Date High [12]     2019    
Weighted Average Interest Rate     2.049%    
Securitization Bonds [Member] | Ohio Power Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     2.049% 2.049%  
Securitization Bonds [Member] | Ohio Power Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     2.049% 2.049%  
Securitization Bonds [Member] | Ohio Power Co [Member] | Subsequent Event [Member]          
Financing Activities (Textuals)          
Repayments of Long-term Debt   23.0      
Other Long Term Debt [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2018    
Maturity Date High     2059    
Weighted Average Interest Rate     3.72%    
Other Long Term Debt [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     1.15% 1.15%  
Other Long Term Debt [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     13.718% 13.718%  
Other Long Term Debt [Member] | AEP Texas Inc. [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2019    
Maturity Date High     2059    
Weighted Average Interest Rate     3.94%    
Other Long Term Debt [Member] | AEP Texas Inc. [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     3.94% 2.75%  
Other Long Term Debt [Member] | AEP Texas Inc. [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     4.50% 4.50%  
Other Long Term Debt [Member] | Appalachian Power Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2019    
Maturity Date High     2026    
Weighted Average Interest Rate     3.91%    
Other Long Term Debt [Member] | Appalachian Power Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     3.74% 2.73%  
Other Long Term Debt [Member] | Appalachian Power Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     13.718% 13.718%  
Other Long Term Debt [Member] | Indiana Michigan Power Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2018    
Maturity Date High     2025    
Weighted Average Interest Rate     3.80%    
Other Long Term Debt [Member] | Indiana Michigan Power Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     3.66% 2.82%  
Other Long Term Debt [Member] | Indiana Michigan Power Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     6.00% 6.00%  
Other Long Term Debt [Member] | Ohio Power Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2028    
Maturity Date High     2028    
Weighted Average Interest Rate     1.15%    
Other Long Term Debt [Member] | Ohio Power Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     1.15% 1.15%  
Other Long Term Debt [Member] | Ohio Power Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     1.15% 1.15%  
Other Long Term Debt [Member] | Public Service Co Of Oklahoma [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2019    
Maturity Date High     2027    
Weighted Average Interest Rate     3.70%    
Other Long Term Debt [Member] | Public Service Co Of Oklahoma [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     3.00% 2.584%  
Other Long Term Debt [Member] | Public Service Co Of Oklahoma [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     3.72% 3.00%  
Other Long Term Debt [Member] | Southwestern Electric Power Co [Member]          
Long- term Debt by Type of Debt and Maturity          
Maturity Date Low     2020    
Maturity Date High     2028    
Weighted Average Interest Rate     4.03%    
Other Long Term Debt [Member] | Southwestern Electric Power Co [Member] | Minimum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     3.75% 2.925%  
Other Long Term Debt [Member] | Southwestern Electric Power Co [Member] | Maximum [Member]          
Long- term Debt by Type of Debt and Maturity          
Interest Rate     4.68% 4.28%  
Other Long Term Debt [Member] | Transource Energy [Member] | Subsequent Event [Member]          
Financing Activities (Textuals)          
Proceeds from Issuance of Long-term Debt $ 3.0 $ 3.0      
Due Date   2020      
July 2020 [Member]          
Financing Activities (Textuals)          
Commitment From Bank Conduits To Finance Receivables     $ 125.0    
July 2021 [Member]          
Financing Activities (Textuals)          
Commitment From Bank Conduits To Finance Receivables     625.0    
Servicing Contracts [Member] | Appalachian Power Co [Member]          
Fees Paid to AEP Credit for Customer Accounts Receivable Sold          
Revenue from Contracts with Customers     7.0 $ 5.6 $ 6.7
Servicing Contracts [Member] | Indiana Michigan Power Co [Member]          
Fees Paid to AEP Credit for Customer Accounts Receivable Sold          
Revenue from Contracts with Customers     9.2 6.7 7.1
Servicing Contracts [Member] | Ohio Power Co [Member]          
Fees Paid to AEP Credit for Customer Accounts Receivable Sold          
Revenue from Contracts with Customers     26.3 21.7 28.9
Servicing Contracts [Member] | Public Service Co Of Oklahoma [Member]          
Fees Paid to AEP Credit for Customer Accounts Receivable Sold          
Revenue from Contracts with Customers     7.9 7.0 6.2
Servicing Contracts [Member] | Southwestern Electric Power Co [Member]          
Fees Paid to AEP Credit for Customer Accounts Receivable Sold          
Revenue from Contracts with Customers     $ 8.9 $ 7.2 $ 6.9
[1] Reissued Treasury Stock used to fulfill share commitments related to AEP’s Share-based Compensation. See “Shared-based Compensation Plans” section of Note 15 for additional information.
[2] For certain series of Pollution Control Bonds, interest rates are subject to periodic adjustment. Certain series may be purchased on demand at periodic interest adjustment dates. Letters of credit from banks and insurance policies support certain series.
[3] Notes payable represent outstanding promissory notes issued under term loan agreements and credit agreements with a number of banks and other financial institutions. At expiration, all notes then issued and outstanding are due and payable. Interest rates are both fixed and variable. Variable rates generally relate to specified short-term interest rates.
[4] Spent Nuclear Fuel Obligation consists of a liability along with accrued interest for disposal of SNF. See “Spent Nuclear Fuel Disposal” section of Note 6 for additional information.
[5] Amount of securitized debt for receivables as accounted for under the “Transfers and Servicing” accounting guidance.
[6] Weighted-average interest rate.
[7] Includes the restrictions of consolidated and non-consolidated subsidiaries.
[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] Amount represents the combined authorized short-term borrowing limit the State Transcos have from FERC or state regulatory commissions.
[10] Amount represents the combined authorized short-term borrowing limit the State Transcos have from FERC or state regulatory commissions.
[11] Certain Pollution Control Bonds are subject to redemption earlier than the maturity date. Consequently, these bonds have been classified for maturity purposes as Long-term Debt Due Within One Year - Nonaffiliated on the balance sheets.
[12] Dates represent the scheduled final payment dates for the securitization bonds. The legal maturity date is one to two years later. These bonds have been classified for maturity and repayment purposes based on the scheduled final payment date.