XML 91 R51.htm IDEA: XBRL DOCUMENT v3.5.0.2
Financing Activities (Details) - USD ($)
$ in Millions
1 Months Ended 3 Months Ended 6 Months Ended
Jul. 28, 2016
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Dec. 31, 2015
Long-term Debt            
Senior Unsecured Notes   $ 13,679.4   $ 13,679.4   $ 13,629.1
Pollution Control Bonds   1,724.2   1,724.2   1,784.8
Notes Payable   297.1   297.1   264.7
Securitization Bonds   1,837.0   1,837.0   2,024.0
Spent Nuclear Fuel Obligation [1]   265.9   265.9   265.6
Other Long-term Debt   1,740.1   1,740.1   1,604.5
Total Long-term Debt Outstanding   19,543.7   19,543.7   19,572.7
Long-term Debt Due Within One Year   2,006.3   2,006.3   1,831.8
Long-term Debt   17,537.4   17,537.4   17,740.9
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Issuances [2]       749.7    
Retirements and Principal Payments       784.1 $ 1,725.7  
Short-term Debt:            
Securitized Debt for Receivables [3]   651.0   651.0   675.0
Commercial Paper   1,409.3   1,409.3   125.0
Total Short-term Debt   $ 2,060.3   $ 2,060.3   $ 800.0
Securitized Debt for Receivables [3],[4]   0.61%   0.61%   0.30%
Comparative Accounts Receivable Information            
Effective Interest Rates on Securitization of Accounts Receivable   0.63% 0.27% 0.61% 0.27%  
Net Uncollectible Accounts Receivable Written Off   $ 4.1 $ 6.3 $ 9.8 $ 12.9  
Customer Accounts Receivable Managed Portfolio            
Accounts Receivable Retained Interest and Pledged as Collateral Less Uncollectible Accounts   963.2   963.2   $ 924.8
Total Principal Outstanding   651.0   651.0   675.0
Delinquent Securitized Accounts Receivable   45.0   45.0   48.3
Bad Debt Reserves Related to Securitization, Sale of Accounts Receivable   25.8   25.8   17.5
Unbilled Receivables Related to Securitization, Sale of Accounts Receivable   372.5   372.5   357.8
Financing Activities (Textuals) [Abstract]            
Trust Fund Assets One Time Fee Obligation for Nuclear Fuel Disposition   309.0   309.0   $ 309.0
Repayments of Long-term Debt       784.1 1,725.7  
Issuance of Long-term Debt [2]       749.7    
Reacquired Pollution Controls Bonds Held by Trustees   614.0   $ 614.0    
Maximum Percentage Debt to Capitalization       67.50%    
Total Commitment from Bank Conduits to Finance Receivables   $ 750.0   $ 750.0    
Commercial Paper [Member]            
Short-term Debt:            
Weighted Average Interest Rate [4]   0.84%   0.84%   0.81%
AEP Subsidiaries [Member]            
Long-term Debt            
Long-term Debt Due Within One Year   $ 383.9   $ 383.9   $ 410.4
Long-term Debt   $ 1,855.9   1,855.9   1,971.4
AEP Subsidiaries [Member] | Notes Payable [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 1.0    
Interest Rate (Variable)       Variable    
Due Date       2017    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 1.0    
Due Date       2017    
AEP Generating Co [Member] | Senior Unsecured Notes [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 3.7    
Interest Rate (Percentage)   6.33%   6.33%    
Due Date       2037    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 3.7    
Interest Rate (Percentage)   6.33%   6.33%    
Due Date       2037    
AEP Generation Resources [Member] | Pollution Control Bonds [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 60.0    
Interest Rate (Variable)       Variable    
Due Date       2016    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 60.0    
Due Date       2016    
AEP Texas Central Co [Member] | Other Long Term Debt [Member] | Subsequent Event [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments $ 100.0          
Due Date 2016          
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt $ 100.0          
Due Date 2016          
AEP Texas Central Co [Member] | Securitization Bonds [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 44.2    
Interest Rate (Percentage)   6.25%   6.25%    
Due Date       2016    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 44.2    
Interest Rate (Percentage)   6.25%   6.25%    
Due Date       2016    
AEP Texas Central Co [Member] | Securitization Bonds [Member] | Subsequent Event [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments $ 65.0          
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt 65.0          
AEP Texas Central Co [Member] | Securitization Bonds Two [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 83.7    
Interest Rate (Percentage)   5.17%   5.17%    
Due Date       2018    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 83.7    
Interest Rate (Percentage)   5.17%   5.17%    
Due Date       2018    
AEP Texas Central Co [Member] | Securitization Bonds Three [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 26.9    
Interest Rate (Percentage)   0.88%   0.88%    
Due Date       2017    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 26.9    
Interest Rate (Percentage)   0.88%   0.88%    
Due Date       2017    
AEP Texas Central Co [Member] | Other Long Term Debt Two [Member] | Subsequent Event [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Issuances $ 125.0          
Due Date 2019          
Financing Activities (Textuals) [Abstract]            
Issuance of Long-term Debt $ 125.0          
Due Date 2019          
Appalachian Power Co [Member]            
Long-term Debt            
Total Long-term Debt Outstanding   $ 4,044.5   $ 4,044.5   3,930.7
Long-term Debt Due Within One Year   568.3   568.3   318.0
Long-term Debt   3,476.2   3,476.2   3,612.7
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       136.5 661.0  
Accounts Receivable and Accrued Unbilled Revenues            
Accounts Receivable and Accrued Unbilled Revenues   125.0   125.0   135.4
Fees Paid to AEP Credit for Customer Accounts Receivable Sold            
Fees Paid to AEP Credit for Customer Accounts Receivable Sold   2.0 1.6 3.8 4.0  
Proceeds from Sale of Receivables            
Proceeds from Sale of Receivables to AEP Credit   325.5 330.6 709.9 760.2  
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 136.5 $ 661.0  
Maximum Percentage Debt to Capitalization       67.50%    
Appalachian Power Co [Member] | Utility [Member]            
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits [Abstract]            
Maximum Borrowings from Money Pool       $ 286.9    
Maximum Loans to Money Pool       25.7    
Average Borrowings from Money Pool       198.1    
Average Loans to Money Pool       25.1    
Net Loans (Borrowings) to/from Money Pool   $ (121.3)   (121.3)    
Authorized Short Term Borrowing Limit       $ 600.0    
Maximum and Minimum Interest Rates            
Maximum Interest Rate       0.84% 0.59%  
Minimum Interest Rate       0.69% 0.39%  
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool [Abstract]            
Average Interest Rate For Funds Borrowed       0.75% 0.45%  
Average Interest Rate For Funds Loaned       0.75% 0.46%  
Appalachian Power Co [Member] | Other Long Term Debt [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Issuances [2]       $ 125.0    
Interest Rate (Variable)       Variable    
Due Date       2019    
Financing Activities (Textuals) [Abstract]            
Issuance of Long-term Debt [2]       $ 125.0    
Due Date       2019    
Appalachian Power Co [Member] | Pollution Control Bonds [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Issuances [2]       $ 125.3    
Retirements and Principal Payments       $ 125.3    
Interest Rate (Variable)       Variable    
Due Date       2016    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 125.3    
Issuance of Long-term Debt [2]       $ 125.3    
Due Date       2016    
Appalachian Power Co [Member] | Securitization Bonds [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 11.2    
Interest Rate (Percentage)   2.008%   2.008%    
Due Date       2024    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 11.2    
Interest Rate (Percentage)   2.008%   2.008%    
Due Date       2024    
Indiana Michigan Power Co [Member]            
Long-term Debt            
Total Long-term Debt Outstanding   $ 2,430.3   $ 2,430.3   2,000.0
Long-term Debt Due Within One Year   174.2   174.2   162.9
Long-term Debt   2,256.1   2,256.1   1,837.1
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       53.5 $ 150.1  
Accounts Receivable and Accrued Unbilled Revenues            
Accounts Receivable and Accrued Unbilled Revenues   140.4   140.4   134.8
Fees Paid to AEP Credit for Customer Accounts Receivable Sold            
Fees Paid to AEP Credit for Customer Accounts Receivable Sold   1.7 2.1 3.6 4.4  
Proceeds from Sale of Receivables            
Proceeds from Sale of Receivables to AEP Credit   384.1 371.1 772.2 790.6  
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       53.5 $ 150.1  
Reacquired Pollution Controls Bonds Held by Trustees   40.0   $ 40.0    
Maximum Percentage Debt to Capitalization       67.50%    
Indiana Michigan Power Co [Member] | Utility [Member]            
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits [Abstract]            
Maximum Borrowings from Money Pool       $ 369.1    
Maximum Loans to Money Pool       97.6    
Average Borrowings from Money Pool       171.7    
Average Loans to Money Pool       25.6    
Net Loans (Borrowings) to/from Money Pool   $ 1.0   1.0    
Authorized Short Term Borrowing Limit       $ 500.0    
Maximum and Minimum Interest Rates            
Maximum Interest Rate       0.84% 0.59%  
Minimum Interest Rate       0.69% 0.39%  
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool [Abstract]            
Average Interest Rate For Funds Borrowed       0.72% 0.47%  
Average Interest Rate For Funds Loaned       0.75% 0.47%  
Indiana Michigan Power Co [Member] | Notes Payable [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Issuances [2]       $ 87.9    
Interest Rate (Variable)       Variable    
Due Date       2020    
Financing Activities (Textuals) [Abstract]            
Issuance of Long-term Debt [2]       $ 87.9    
Due Date       2020    
Indiana Michigan Power Co [Member] | Notes Payable Two [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 0.5    
Interest Rate (Variable)       0.0212    
Due Date       2016    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 0.5    
Due Date       2016    
Indiana Michigan Power Co [Member] | Notes Payable Three [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 10.9    
Interest Rate (Variable)       Variable    
Due Date       2017    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 10.9    
Due Date       2017    
Indiana Michigan Power Co [Member] | Notes Payable Four [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 19.3    
Interest Rate (Variable)       Variable    
Due Date       2019    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 19.3    
Due Date       2019    
Indiana Michigan Power Co [Member] | Notes Payable Five [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 21.3    
Interest Rate (Variable)       Variable    
Due Date       2019    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 21.3    
Due Date       2019    
Indiana Michigan Power Co [Member] | Other Long Term Debt [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 0.7    
Interest Rate (Percentage)   6.00%   6.00%    
Due Date       2025    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 0.7    
Interest Rate (Percentage)   6.00%   6.00%    
Due Date       2025    
Indiana Michigan Power Co [Member] | Senior Unsecured Notes [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Issuances [2]       $ 400.0    
Interest Rate (Percentage)   4.55%   4.55%    
Due Date       2046    
Financing Activities (Textuals) [Abstract]            
Issuance of Long-term Debt [2]       $ 400.0    
Interest Rate (Percentage)   4.55%   4.55%    
Due Date       2046    
Indiana Michigan Power Co [Member] | Notes Payable [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 0.8    
Interest Rate (Variable)       Variable    
Due Date       2016    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 0.8    
Due Date       2016    
Indiana Michigan Power Co [Member] | Notes Payable [Member] | Subsequent Event [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments $ 9.0          
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt 9.0          
Ohio Power Co [Member]            
Long-term Debt            
Total Long-term Debt Outstanding   $ 1,786.0   $ 1,786.0   2,157.7
Long-term Debt Due Within One Year   45.6   45.6   395.9
Long-term Debt   1,740.4   1,740.4   1,761.8
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       372.8 $ 108.2  
Accounts Receivable and Accrued Unbilled Revenues            
Accounts Receivable and Accrued Unbilled Revenues   364.0   364.0   351.4
Fees Paid to AEP Credit for Customer Accounts Receivable Sold            
Fees Paid to AEP Credit for Customer Accounts Receivable Sold   7.4 6.7 15.3 14.7  
Proceeds from Sale of Receivables            
Proceeds from Sale of Receivables to AEP Credit   613.7 563.4 1,260.3 1,278.4  
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       372.8 $ 108.2  
Reacquired Pollution Controls Bonds Held by Trustees   345.0   345.0    
Ohio Power Co [Member] | Utility [Member]            
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits [Abstract]            
Maximum Borrowings from Money Pool       216.9    
Maximum Loans to Money Pool       379.2    
Average Borrowings from Money Pool       184.0    
Average Loans to Money Pool       265.5    
Net Loans (Borrowings) to/from Money Pool   $ (177.1)   (177.1)    
Authorized Short Term Borrowing Limit       $ 400.0    
Maximum and Minimum Interest Rates            
Maximum Interest Rate       0.84% 0.59%  
Minimum Interest Rate       0.69% 0.39%  
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool [Abstract]            
Average Interest Rate For Funds Borrowed       0.79% 0.00%  
Average Interest Rate For Funds Loaned       0.74% 0.47%  
Ohio Power Co [Member] | Securitization Bonds [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 22.8    
Interest Rate (Percentage)   0.958%   0.958%    
Due Date       2018    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 22.8    
Interest Rate (Percentage)   0.958%   0.958%    
Due Date       2018    
Ohio Power Co [Member] | Securitization Bonds [Member] | Subsequent Event [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments 23.0          
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt 23.0          
Ohio Power Co [Member] | Senior Unsecured Notes [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 350.0    
Interest Rate (Percentage)   6.00%   6.00%    
Due Date       2016    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 350.0    
Interest Rate (Percentage)   6.00%   6.00%    
Due Date       2016    
Public Service Co Of Oklahoma [Member]            
Long-term Debt            
Total Long-term Debt Outstanding   $ 1,286.4   $ 1,286.4   1,286.1
Long-term Debt Due Within One Year   125.4   125.4   275.4
Long-term Debt   1,161.0   1,161.0   1,010.7
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       0.2 $ 0.2  
Accounts Receivable and Accrued Unbilled Revenues            
Accounts Receivable and Accrued Unbilled Revenues   137.5   137.5   116.1
Fees Paid to AEP Credit for Customer Accounts Receivable Sold            
Fees Paid to AEP Credit for Customer Accounts Receivable Sold   1.5 1.3 2.9 2.7  
Proceeds from Sale of Receivables            
Proceeds from Sale of Receivables to AEP Credit   309.2 311.9 581.3 614.4  
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 0.2 $ 0.2  
Maximum Percentage Debt to Capitalization       67.50%    
Public Service Co Of Oklahoma [Member] | Utility [Member]            
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits [Abstract]            
Maximum Borrowings from Money Pool       $ 9.6    
Maximum Loans to Money Pool       91.0    
Average Borrowings from Money Pool       5.1    
Average Loans to Money Pool       32.1    
Net Loans (Borrowings) to/from Money Pool   $ 33.5   33.5    
Authorized Short Term Borrowing Limit       $ 300.0    
Maximum and Minimum Interest Rates            
Maximum Interest Rate       0.84% 0.59%  
Minimum Interest Rate       0.69% 0.39%  
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool [Abstract]            
Average Interest Rate For Funds Borrowed       0.76% 0.49%  
Average Interest Rate For Funds Loaned       0.73% 0.47%  
Public Service Co Of Oklahoma [Member] | Other Long Term Debt [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 0.2    
Interest Rate (Percentage)   3.00%   3.00%    
Due Date       2027    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 0.2    
Interest Rate (Percentage)   3.00%   3.00%    
Due Date       2027    
Public Service Co Of Oklahoma [Member] | Senior Unsecured Notes [Member] | Subsequent Event [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Issuances [2] $ 50.0          
Interest Rate (Percentage) 3.05%          
Due Date 2026          
Financing Activities (Textuals) [Abstract]            
Issuance of Long-term Debt [2] $ 50.0          
Interest Rate (Percentage) 3.05%          
Due Date 2026          
Public Service Co Of Oklahoma [Member] | Senior Unsecured Notes Two [Member] | Subsequent Event [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Issuances [2] $ 100.0          
Interest Rate (Percentage) 4.11%          
Due Date 2046          
Financing Activities (Textuals) [Abstract]            
Issuance of Long-term Debt [2] $ 100.0          
Interest Rate (Percentage) 4.11%          
Due Date 2046          
Southwestern Electric Power Co [Member]            
Long-term Debt            
Total Long-term Debt Outstanding   $ 2,272.8   $ 2,272.8   2,273.5
Long-term Debt Due Within One Year   253.3   253.3   3.3
Long-term Debt   2,019.5   2,019.5   2,270.2
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       1.6 $ 155.1  
Accounts Receivable and Accrued Unbilled Revenues            
Accounts Receivable and Accrued Unbilled Revenues   167.2   167.2   $ 151.8
Fees Paid to AEP Credit for Customer Accounts Receivable Sold            
Fees Paid to AEP Credit for Customer Accounts Receivable Sold   1.7 1.6 3.2 3.3  
Proceeds from Sale of Receivables            
Proceeds from Sale of Receivables to AEP Credit   387.4 $ 381.1 723.5 754.3  
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 1.6 $ 155.1  
Maximum Percentage Debt to Capitalization       67.50%    
Southwestern Electric Power Co [Member] | Utility [Member]            
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits [Abstract]            
Maximum Borrowings from Money Pool       $ 249.4    
Maximum Loans to Money Pool       0.0    
Average Borrowings from Money Pool       181.9    
Average Loans to Money Pool       0.0    
Net Loans (Borrowings) to/from Money Pool   (155.1)   (155.1)    
Authorized Short Term Borrowing Limit       $ 350.0    
Maximum and Minimum Interest Rates            
Maximum Interest Rate       0.84% 0.59%  
Minimum Interest Rate       0.69% 0.39%  
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool [Abstract]            
Average Interest Rate For Funds Borrowed       0.75% 0.46%  
Average Interest Rate For Funds Loaned       0.00% 0.49%  
Southwestern Electric Power Co [Member] | Nonutility [Member]            
Money Pool Participants Money Pool Activity And Authorized Borrowing Limits [Abstract]            
Maximum Loans to Money Pool       $ 2.0    
Average Loans to Money Pool       2.0    
Net Loans To Borrowings From Nonutility Money Pool   $ 2.0   $ 2.0    
Maximum and Minimum Interest Rates            
Maximum Interest Rate       0.84%    
Minimum Interest Rate       0.69%    
Average Interest Rates for Funds Borrowed From and Loaned to Money Pool [Abstract]            
Average Interest Rate For Funds Loaned       0.75%    
Southwestern Electric Power Co [Member] | Notes Payable [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments       $ 1.6    
Interest Rate (Percentage)   4.58%   4.58%    
Due Date       2032    
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt       $ 1.6    
Interest Rate (Percentage)   4.58%   4.58%    
Due Date       2032    
Transource Missouri [Member] | Other Long Term Debt [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Issuances [2]       $ 11.5    
Interest Rate (Variable)       Variable    
Due Date       2018    
Financing Activities (Textuals) [Abstract]            
Issuance of Long-term Debt [2]       $ 11.5    
Due Date       2018    
AEP Texas North Co [Member] | Other Long Term Debt [Member] | Subsequent Event [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Retirements and Principal Payments $ 75.0          
Due Date 2016          
Financing Activities (Textuals) [Abstract]            
Repayments of Long-term Debt $ 75.0          
Due Date 2016          
AEP Texas North Co [Member] | Other Long Term Debt Two [Member] | Subsequent Event [Member]            
Long-term Debt and Other Securities Issued, Retired and Principal Payments Made            
Issuances $ 75.0          
Due Date 2019          
Financing Activities (Textuals) [Abstract]            
Issuance of Long-term Debt $ 75.0          
Due Date 2019          
[1] Pursuant to the Nuclear Waste Policy Act of 1982, I&M, a nuclear licensee, has an obligation to the United States Department of Energy for spent nuclear fuel disposal. The obligation includes a one-time fee for nuclear fuel consumed prior to April 7, 1983. Trust fund assets related to this obligation were $309 million and $309 million as of June 30, 2016 and December 31, 2015, respectively, and are included in Spent Nuclear Fuel and Decommissioning Trusts on the balance sheets.
[2] Amounts indicated on the statements of cash flows are net of issuance costs and premium or discount and will not tie to the issuance amounts.
[3] Amount of securitized debt for receivables as accounted for under the “Transfers and Servicing” accounting guidance.
[4] Weighted average rate.