Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Current Assets
Cash and Cash Equivalents	$ 190.4	$ 176.4
Other Temporary Investments	264.5	386.8
Fuel	701.6	600.8
Property, Plant and Equipment
Other Property, Plant and Equipment	3,812.3	3,722.9
Accumulated Depreciation and Amortization	19,597.3	19,348.2
Current Liabilities
Long-term Debt Due Within One Year	2,033.3	1,831.8
Noncurrent Liabilities
Long-term Debt	$ 17,749.3	$ 17,740.9
Equity
Common Stock, Par Value Per Share	$ 6.50	$ 6.50
Common Stock, Shares Authorized	600,000,000	600,000,000
Common Stock, Shares, Issued	511,579,970	511,389,173
Treasury Stock, Shares	20,336,592	20,336,592
Appalachian Power Co [Member]
Current Assets
Cash and Cash Equivalents	$ 6.4	$ 2.8
Fuel	147.7	119.3
Property, Plant and Equipment
Other Property, Plant and Equipment	357.2	345.5
Accumulated Depreciation and Amortization	3,473.5	3,407.6
Current Liabilities
Long-term Debt Due Within One Year	318.3	318.0
Noncurrent Liabilities
Long-term Debt	$ 3,601.0	$ 3,612.7
Equity
Common Stock, Shares Authorized	30,000,000	30,000,000
Common Stock, Shares Outstanding	13,499,500	13,499,500
Indiana Michigan Power Co [Member]
Current Assets
Cash and Cash Equivalents	$ 3.3	$ 1.1
Fuel	63.7	46.5
Property, Plant and Equipment
Other Property, Plant and Equipment	672.5	662.3
Accumulated Depreciation and Amortization	3,048.3	3,018.0
Current Liabilities
Long-term Debt Due Within One Year	151.5	162.9
Noncurrent Liabilities
Long-term Debt	$ 2,215.1	$ 1,837.1
Equity
Common Stock, No Par Value	$ 0	$ 0
Common Stock, Shares Authorized	2,500,000	2,500,000
Common Stock, Shares Outstanding	1,400,000	1,400,000
Indiana Michigan Power Co [Member] | DCC Fuel [Member]
Current Liabilities
Long-term Debt Due Within One Year	$ 73,200.0	$ 84,600.0
Ohio Power Co [Member]
Current Assets
Cash and Cash Equivalents	9.3	3.1
Property, Plant and Equipment
Other Property, Plant and Equipment	423.1	408.2
Accumulated Depreciation and Amortization	2,070.4	2,048.7
Current Liabilities
Long-term Debt Due Within One Year	395.6	395.9
Noncurrent Liabilities
Long-term Debt	$ 1,739.9	$ 1,761.8
Equity
Common Stock, No Par Value	$ 0	$ 0
Common Stock, Shares Authorized	40,000,000	40,000,000
Common Stock, Shares Outstanding	27,952,473	27,952,473
Ohio Power Co [Member] | Ohio Phase-In-Recovery Funding [Member]
Current Liabilities
Long-term Debt Due Within One Year	$ 45.6	$ 45.9
Noncurrent Liabilities
Long-term Debt	117.2	139.4
Public Service Co Of Oklahoma [Member]
Current Assets
Cash and Cash Equivalents	3.2	1.4
Fuel	21.2	17.6
Property, Plant and Equipment
Other Property, Plant and Equipment	414.4	405.7
Accumulated Depreciation and Amortization	1,365.7	1,352.5
Current Liabilities
Long-term Debt Due Within One Year	275.4	275.4
Noncurrent Liabilities
Long-term Debt	$ 1,010.9	$ 1,010.7
Equity
Common Stock, Par Value Per Share	$ 15	$ 15
Common Stock, Shares Authorized	11,000,000	11,000,000
Common Stock, Shares, Issued	10,482,000	10,482,000
Common Stock, Shares Outstanding	9,013,000	9,013,000
Southwestern Electric Power Co [Member]
Current Assets
Cash and Cash Equivalents	$ 12.3	$ 5.2
Fuel	129.3	142.1
Property, Plant and Equipment
Other Property, Plant and Equipment	893.2	883.5
Accumulated Depreciation and Amortization	2,620.9	2,602.3
Current Liabilities
Long-term Debt Due Within One Year	253.3	3.3
Noncurrent Liabilities
Long-term Debt	$ 2,019.1	$ 2,270.2
Equity
Common Stock, Par Value Per Share	$ 18	$ 18
Common Stock, Shares Authorized	7,600,000	7,600,000
Common Stock, Shares Outstanding	7,536,640	7,536,640
Southwestern Electric Power Co [Member] | Sabine Mining Co [Member]
Current Assets
Cash and Cash Equivalents	$ 9.4	$ 3.7
Fuel	36.1	40.4
Property, Plant and Equipment
Other Property, Plant and Equipment	300.5	297.7
Accumulated Depreciation and Amortization	161.1	157.3
AEP Subsidiaries [Member]
Current Assets
Other Temporary Investments	250.0	376.6
Current Liabilities
Long-term Debt Due Within One Year	361.0	410.4
Noncurrent Liabilities
Long-term Debt	$ 1,835.3	$ 1,971.4