The 2013 reversal of previously recorded regulatory disallowances.

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2016 revenues related to advanced metering costs as approved in stipulation agreement.

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AEP's share of ETT's cumulative revenues, subject to review, based upon interim rate increases received from 2009 through 2015.

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Additional requested annual increase.

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Amount of requested increase related to environmental controls to be installed at certain plants.

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No definition available.

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Amount of increased depreciation expense requested.

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Amount of interim rates implemented in January 2015, subject to refund, as approved by the LPSC in partial settlement agreement.

+ References

No definition available.

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Amount of the requested increase related to environmental consumable costs included in the FAC.

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Base rate increase per the settlement agreement.

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Fourteen months of revenue beginning November 2014 related to advanced metering costs as approved in stipulation agreement.

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No definition available.

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Fuel rate decrease per the settlement agreement.

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Future incremental purchased capacity and energy costs that will be incurred related to the environmental compliance plan.

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Intervenor recommended increase to annual revenue and/or rider.

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No definition available.

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Intervenor recommended increase to depreciation expense.

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Intervenor recommended return on common equity.

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No definition available.

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- Definition

Louisiana jurisdictional share of the Turk Plant.

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No definition available.

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Net increase in Louisiana total rates per the settlement agreement.

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No definition available.

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- Definition

Parents equity ownership interest in ETT.

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No definition available.

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Projected capital costs of property, plant and equipment.

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- Definition

Reduction to the requested revenue increase as approved by the LPSC in the stipulation agreement.

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No definition available.

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Requested annual increase.

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No definition available.

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Requested base rate increase.

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No definition available.

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Requested return on equity.

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Requested total annual increase.

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- Definition

The resulting annual base rate increase subsequent to recent rulings by the PUCT.

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No definition available.

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Return on common equity for AFUDC and Factoring as approved in Stipulation Agreement.

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Return on common equity per the settlement agreement.

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- Definition

Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of public utility's interim rate increase (decrease) allowed while waiting final decision of regulatory agency.

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Period end amount of total net PPE.

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Amount of the recorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Rate Matters - West Companies (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Public Utilities, General Disclosures [Line Items]
Construction Work in Progress		$ 3,903.9	$ 3,215.3
Remaining Contractual Construction Obligations		10,488.8
Public Service Co Of Oklahoma [Member]
Public Utilities, General Disclosures [Line Items]
Construction Work in Progress		315.3	204.8
Remaining Contractual Construction Obligations		1,113.3
Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Construction Work in Progress		751.3	$ 472.0
Remaining Contractual Construction Obligations		854.1
Welsh Plant, Unit 2 [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment, Net		82.0
Welsh Plant, Unit 2 [Member] \| Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment, Net		$ 82.0
ETT Interim Transmission Rates [Member]
Public Utilities, General Disclosures [Line Items]
Parent Equity Ownership Interest in ETT		50.00%
AEP Share of ETT Cumulative Revenues Subject to Review		$ 433.0
Louisiana 2012 Formula Rate Filing [Member]
Public Utilities, General Disclosures [Line Items]
Louisiana Jurisdictional Share of the Turk Plant		29.00%
Net Increase in Louisiana Total Rates per the Settlement Agreement		$ 2.0
Base Rate Increase per the Settlement Agreement		85.0
Fuel Rate Decrease per the Settlement Agreement		$ 83.0
Return on Common Equity per the Settlement Agreement		10.00%
Reduction to Requested Revenue Increase as Approved in Stipulation Agreement		$ 3.0
Louisiana 2012 Formula Rate Filing [Member] \| Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Louisiana Jurisdictional Share of the Turk Plant		29.00%
Net Increase in Louisiana Total Rates per the Settlement Agreement		$ 2.0
Base Rate Increase per the Settlement Agreement		85.0
Fuel Rate Decrease per the Settlement Agreement		$ 83.0
Return on Common Equity per the Settlement Agreement		10.00%
Reduction to Requested Revenue Increase as Approved in Stipulation Agreement		$ 3.0
Louisiana 2014 Formula Rate Filing [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase		5.0
Additional Requested Annual Increase		15.0
Requested Total Annual Increase		20.0
Amount Of Interim Rates Implemented In January 2015 As Approved In Partial Settlement Agreement		15.0
Louisiana 2014 Formula Rate Filing [Member] \| Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase		5.0
Additional Requested Annual Increase		15.0
Requested Total Annual Increase		20.0
Amount Of Interim Rates Implemented In January 2015 As Approved In Partial Settlement Agreement		15.0
Louisiana 2015 Formula Rate Filing [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase		14.0
Louisiana 2015 Formula Rate Filing [Member] \| Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase		14.0
Oklahoma 2014 Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Fourteen Months of Revenues Beginning November 2014 Related to Advanced Metering Costs as Approved in Stipulation Agreement		24.0
2016 Revenues Related to Advanced Metering Costs as Approved in Stipulation Agreement		$ 27.0
Return on Common Equity for AFUDC and Factoring as Approved in Stipulation Agreement		9.85%
Oklahoma 2014 Base Rate Case [Member] \| Public Service Co Of Oklahoma [Member]
Public Utilities, General Disclosures [Line Items]
Fourteen Months of Revenues Beginning November 2014 Related to Advanced Metering Costs as Approved in Stipulation Agreement		$ 24.0
2016 Revenues Related to Advanced Metering Costs as Approved in Stipulation Agreement		$ 27.0
Return on Common Equity for AFUDC and Factoring as Approved in Stipulation Agreement		9.85%
Oklahoma 2015 Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase		$ 137.0
Requested Base Rate Increase		89.0
Amount of Increased Depreciation Expense Requested		48.0
Amount of Increase Related to Environmental Controls		44.0
Amount of Requested Increase Related to Environmental Consumable Costs in the FAC		$ 4.0
Requested Return on Equity		10.50%
Future Incremental Purchased Capacity and Energy Costs Related to Environmental Projects		$ 35.0
Property, Plant and Equipment, Net		93.0
Oklahoma 2015 Base Rate Case [Member] \| Public Service Co Of Oklahoma [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase		137.0
Requested Base Rate Increase		89.0
Amount of Increased Depreciation Expense Requested		48.0
Amount of Increase Related to Environmental Controls		44.0
Amount of Requested Increase Related to Environmental Consumable Costs in the FAC		$ 4.0
Requested Return on Equity		10.50%
Future Incremental Purchased Capacity and Energy Costs Related to Environmental Projects		$ 35.0
Property, Plant and Equipment, Net		93.0
Texas Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
2013 Reversal of Previously Recorded Regulatory Disallowances		114.0
Resulting Approved Base Rate Increase		52.0
Texas Base Rate Case [Member] \| Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
2013 Reversal of Previously Recorded Regulatory Disallowances		114.0
Resulting Approved Base Rate Increase		52.0
Welsh Plant, Units 1 and 3 - Environmental Projects [Member]
Public Utilities, General Disclosures [Line Items]
Projected Capital Costs		900.0
Construction Work in Progress		343.0
Remaining Contractual Construction Obligations		40.0
Welsh Plant, Units 1 and 3 - Environmental Projects [Member] \| Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Projected Capital Costs		900.0
Construction Work in Progress		343.0
Remaining Contractual Construction Obligations		40.0
Welsh Plant, Units 1 and 3 - Environmental Projects [Member] \| Welsh Plant, Units 1 and 3 [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment, Net		578.0
Welsh Plant, Units 1 and 3 - Environmental Projects [Member] \| Welsh Plant, Units 1 and 3 [Member] \| Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment, Net		578.0
Minimum [Member] \| Oklahoma 2015 Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended Increase to Annual Revenue and/or Rider		$ 10.0
Intervenor Recommended Return on Common Equity Range		8.75%
Intervenor Recommended Increase to Depreciation Expense		$ 23.0
Minimum [Member] \| Oklahoma 2015 Base Rate Case [Member] \| Public Service Co Of Oklahoma [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended Increase to Annual Revenue and/or Rider		$ 10.0
Intervenor Recommended Return on Common Equity Range		8.75%
Intervenor Recommended Increase to Depreciation Expense		$ 23.0
Maximum [Member] \| Oklahoma 2015 Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended Increase to Annual Revenue and/or Rider		$ 31.0
Intervenor Recommended Return on Common Equity Range		9.30%
Intervenor Recommended Increase to Depreciation Expense		$ 46.0
Maximum [Member] \| Oklahoma 2015 Base Rate Case [Member] \| Public Service Co Of Oklahoma [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended Increase to Annual Revenue and/or Rider		$ 31.0
Intervenor Recommended Return on Common Equity Range		9.30%
Intervenor Recommended Increase to Depreciation Expense		$ 46.0
Subsequent Event [Member] \| Oklahoma 2015 Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Interim Annual Base Rate Increase	$ 75.0
Subsequent Event [Member] \| Oklahoma 2015 Base Rate Case [Member] \| Public Service Co Of Oklahoma [Member]
Public Utilities, General Disclosures [Line Items]
Interim Annual Base Rate Increase	$ 75.0
Mercury and Air Toxic Standards [Member] \| Welsh Plant, Units 1 and 3 - Environmental Projects [Member]
Public Utilities, General Disclosures [Line Items]
Projected Capital Costs		400.0
Mercury and Air Toxic Standards [Member] \| Welsh Plant, Units 1 and 3 - Environmental Projects [Member] \| Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Projected Capital Costs		400.0
Environmental Controls Projects [Member] \| Oklahoma 2015 Base Rate Case [Member] \| Northeastern Plant, Unit 3 And Comanche Plant [Member]
Public Utilities, General Disclosures [Line Items]
Projected Capital Costs		219.0
Construction Work in Progress		190.0
Environmental Controls Projects [Member] \| Oklahoma 2015 Base Rate Case [Member] \| Northeastern Plant, Unit 3 And Comanche Plant [Member] \| Public Service Co Of Oklahoma [Member]
Public Utilities, General Disclosures [Line Items]
Projected Capital Costs		219.0
Construction Work in Progress		$ 190.0