Rate Matters - East Companies (Details) $ in Millions	6 Months Ended
	Jun. 30, 2016 USD ($) $ / MWh $ / MWD MW	Dec. 31, 2015 USD ($)
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	$ 5,259.1	$ 5,140.3
Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	1,143.7	1,154.2
Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	836.9	804.3
Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	1,004.3	$ 1,113.0
Kingsport 2015 Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Requested Base Rate Increase	$ 12.0
Requested Return on Common Equity	10.66%
Intervenor Recommended Increase in Base Rates	$ 7.0
Intervenor Recommended Return on Common Equity	8.80%
Ohio Electric Security Plan Filing [Member]
Public Utilities, General Disclosures [Line Items]
Proposed Increase in PIRR Rates	$ 146.0
Amount of Recovery Requested for Under-Recovered Fuel Costs	$ 40.0
PUCO-ordered Fixed Price per MW Day for Customers Who Switch During ESP Period | $ / MWD	188.88
Reliability Pricing Model Rate per MW Day in Effect through May 2014 | $ / MWD	34
Reliability Pricing Model Rate per MW Day in Effect from June 2014 through May 2015 | $ / MWD	150
Energy Credit Offset Applied Against the Capacity Deferral Threshold (per MW day) | $ / MWD	147.41
Overstatement of Energy Credit Used in the Determination of the Capacity Deferral Threshold (per MW day) | $ / MWD	100
Retail Stability Rider through May 2014 ($ Per MWh) | $ / MWh	3.50
Retail Stability Rider for the Period June 2014 through May 2015 ($ per MWh) | $ / MWh	4.00
Amount of Retail Stability Rider Applied to the Deferred Capacity Costs ($ per MWh) | $ / MWh	1.00
Retail Stability Rider Rate to be Continued Until Capacity Deferral Balance is Collected as Ordered by the PUCO ($ per MWh) | $ / MWh	4.00
Annual Retail Share of Fixed Fuel Costs	$ 90.0
Approved Return on Common Equity	10.20%
Amount Of Potential Customer Credits To Be Included In PPA Rider Over Final Four Years As Proposed In Stipulation Agreement	$ 100.0
Temporary Customer-Specific Rate Impact Cap Through May 2018	5.00%
Solar Energy Projects To Be Developed And Implemented By 2021 As Proposed In Stipulation Agreement | MW	400
Wind Energy Projects To Be Developed And Implemented By 2021 As Proposed In Stipulation Agreement | MW	500
Percentage of Output to be Received from Solar and Wind Projects as Proposed in Stipulation Agreement	100.00%
Maximum Ownership Percentage of Solar and Wind Projects as Proposed in Stipulation Agreement	50.00%
Return on Common Equity Proposed in the Amended ESP Filing	10.41%
Future Commitment To Support Development Of Large Solar Farm	$ 20.0
Gridsmart Investment as Proposed in Stipulation Agreement	$ 20.0
Significantly Excessive Earnings Test Threshold Previously Established for Ohio Power	12.00%
Significantly Excessive Earnings Test Threshold Remanded Back to the PUCO	12.00%
Ohio Electric Security Plan Filing [Member] | Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Proposed Increase in PIRR Rates	$ 146.0
Amount of Recovery Requested for Under-Recovered Fuel Costs	$ 40.0
PUCO-ordered Fixed Price per MW Day for Customers Who Switch During ESP Period | $ / MWD	188.88
Reliability Pricing Model Rate per MW Day in Effect through May 2014 | $ / MWD	34
Reliability Pricing Model Rate per MW Day in Effect from June 2014 through May 2015 | $ / MWD	150
Energy Credit Offset Applied Against the Capacity Deferral Threshold (per MW day) | $ / MWD	147.41
Overstatement of Energy Credit Used in the Determination of the Capacity Deferral Threshold (per MW day) | $ / MWD	100
Retail Stability Rider through May 2014 ($ Per MWh) | $ / MWh	3.50
Retail Stability Rider for the Period June 2014 through May 2015 ($ per MWh) | $ / MWh	4.00
Amount of Retail Stability Rider Applied to the Deferred Capacity Costs ($ per MWh) | $ / MWh	1.00
Retail Stability Rider Rate to be Continued Until Capacity Deferral Balance is Collected as Ordered by the PUCO ($ per MWh) | $ / MWh	4.00
Annual Retail Share of Fixed Fuel Costs	$ 90.0
Approved Return on Common Equity	10.20%
Amount Of Potential Customer Credits To Be Included In PPA Rider Over Final Four Years As Proposed In Stipulation Agreement	$ 100.0
Temporary Customer-Specific Rate Impact Cap Through May 2018	5.00%
Solar Energy Projects To Be Developed And Implemented By 2021 As Proposed In Stipulation Agreement | MW	400
Wind Energy Projects To Be Developed And Implemented By 2021 As Proposed In Stipulation Agreement | MW	500
Percentage of Output to be Received from Solar and Wind Projects as Proposed in Stipulation Agreement	100.00%
Maximum Ownership Percentage of Solar and Wind Projects as Proposed in Stipulation Agreement	50.00%
Return on Common Equity Proposed in the Amended ESP Filing	10.41%
Future Commitment To Support Development Of Large Solar Farm	$ 20.0
Gridsmart Investment as Proposed in Stipulation Agreement	$ 20.0
Significantly Excessive Earnings Test Threshold Previously Established for Ohio Power	12.00%
Significantly Excessive Earnings Test Threshold Remanded Back to the PUCO	12.00%
Ohio Fuel Adjustment Clause Audit - 2009 [Member]
Public Utilities, General Disclosures [Line Items]
2008 Coal Contract Settlement Proceeds to be Applied to Deferred Fuel Balance as Originally Ordered by the PUCO	$ 65.0
Net Favorable Fuel Adjustment Recorded In 2012 Based On Fuel Adjustment Clause Audit Rehearing	30.0
Ohio Fuel Adjustment Clause Audit - 2009 [Member] | Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
2008 Coal Contract Settlement Proceeds to be Applied to Deferred Fuel Balance as Originally Ordered by the PUCO	65.0
Net Favorable Fuel Adjustment Recorded In 2012 Based On Fuel Adjustment Clause Audit Rehearing	30.0
Special Rate Mechanism For Ormet [Member]
Public Utilities, General Disclosures [Line Items]
Deferred Fuel Adjustment Clause Related to Ormet Interim Arrangement as of September 2009	64.0
Unrecognized Equity Carrying Costs Related to Ormet Interim Arrangement as of September 2009	2.0
Special Rate Mechanism For Ormet [Member] | Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Deferred Fuel Adjustment Clause Related to Ormet Interim Arrangement as of September 2009	64.0
Unrecognized Equity Carrying Costs Related to Ormet Interim Arrangement as of September 2009	2.0
Virginia Regulatory Asset Proceeding - 2015 [Member]
Public Utilities, General Disclosures [Line Items]
Amounts Of Regulatory Assets Under Review In Separate Proceeding	7.0
Virginia Regulatory Asset Proceeding - 2015 [Member] | Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Amounts Of Regulatory Assets Under Review In Separate Proceeding	7.0
West Virginia Deferred Base Rate Increase [Member]
Public Utilities, General Disclosures [Line Items]
Amount of Annual Delayed Customer Billing to Residential Customers	25.0
Amount of Recovery Requested Related to Delayed Billing Including Carrying Charges	29.0
Amount of Recovery Approved Related to Delayed Billing Including Carrying Charges	29.0
West Virginia Deferred Base Rate Increase [Member] | Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Amount of Annual Delayed Customer Billing to Residential Customers	22.0
Amount of Recovery Requested Related to Delayed Billing Including Carrying Charges	26.0
Amount of Recovery Approved Related to Delayed Billing Including Carrying Charges	27.0
West Virginia Expanded Net Energy Charge - 2016 [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase	108.0
Proposed Additional ENEC Revenues Per Settlement Agreement	38.0
Proposed Construction Surcharge Revenues Per Settlement Agreement	17.0
West Virginia Expanded Net Energy Charge - 2016 [Member] | Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase	86.0
Proposed Additional ENEC Revenues Per Settlement Agreement	30.0
Proposed Construction Surcharge Revenues Per Settlement Agreement	$ 14.0
Deferred Capacity Costs [Member] | Ohio Electric Security Plan Filing [Member]
Public Utilities, General Disclosures [Line Items]
Deferred Capacity Costs Recovery Period as Ordered by PUCO (in months)	32 months
Regulatory Assets, Noncurrent	$ 285.0
Requested Net Increase in Deferred Capacity Costs	157.0
Amount of Decrease in Capacity Costs Related to Non-Deferral Portion of RSR Collections	327.0
Amount of Increase in Capacity Costs Related to the Correction of the Energy Credit	$ 484.0
Deferred Capacity Costs [Member] | Ohio Electric Security Plan Filing [Member] | Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Deferred Capacity Costs Recovery Period as Ordered by PUCO (in months)	32 months
Regulatory Assets, Noncurrent	$ 285.0
Requested Net Increase in Deferred Capacity Costs	157.0
Amount of Decrease in Capacity Costs Related to Non-Deferral Portion of RSR Collections	327.0
Amount of Increase in Capacity Costs Related to the Correction of the Energy Credit	$ 484.0