Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Current Assets
Cash and Cash Equivalents	$ 212.2	$ 176.4
Other Temporary Investments	279.2	386.8
Fuel	468.0	600.8
Property, Plant and Equipment
Other Property, Plant and Equipment	3,467.5	3,722.9
Accumulated Depreciation and Amortization	16,337.6	19,348.2
Current Liabilities
Long-term Debt Due Within One Year	2,384.8	1,831.8
Noncurrent Liabilities
Long-term Debt	$ 17,319.9	$ 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	512,046,044	511,389,173
Treasury Stock, Shares	20,336,592	20,336,592
Appalachian Power Co [Member]
Current Assets
Cash and Cash Equivalents	$ 3.3	$ 2.8
Fuel	124.8	119.3
Property, Plant and Equipment
Other Property, Plant and Equipment	368.7	345.5
Accumulated Depreciation and Amortization	3,598.1	3,407.6
Current Liabilities
Long-term Debt Due Within One Year	503.1	318.0
Noncurrent Liabilities
Long-term Debt	$ 3,530.0	$ 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	$ 1.6	$ 1.1
Fuel	48.6	46.5
Property, Plant and Equipment
Other Property, Plant and Equipment	623.8	662.3
Accumulated Depreciation and Amortization	3,063.9	3,018.0
Current Liabilities
Long-term Debt Due Within One Year	176.1	162.9
Noncurrent Liabilities
Long-term Debt	$ 2,231.3	$ 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	$ 97.8	$ 84.6
Ohio Power Co [Member]
Current Assets
Cash and Cash Equivalents	4.0	3.1
Property, Plant and Equipment
Other Property, Plant and Equipment	436.7	408.2
Accumulated Depreciation and Amortization	2,107.1	2,048.7
Current Liabilities
Long-term Debt Due Within One Year	46.4	395.9
Noncurrent Liabilities
Long-term Debt	$ 1,717.0	$ 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	$ 46.3	$ 45.9
Noncurrent Liabilities
Long-term Debt	93.7	139.4
Public Service Co Of Oklahoma [Member]
Current Assets
Cash and Cash Equivalents	2.0	1.4
Fuel	21.8	17.6
Property, Plant and Equipment
Other Property, Plant and Equipment	243.0	405.7
Accumulated Depreciation and Amortization	1,297.4	1,352.5
Current Liabilities
Long-term Debt Due Within One Year	125.5	275.4
Noncurrent Liabilities
Long-term Debt	$ 1,160.7	$ 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	$ 15.2	$ 5.2
Fuel	109.4	142.1
Property, Plant and Equipment
Other Property, Plant and Equipment	707.1	883.5
Accumulated Depreciation and Amortization	2,572.4	2,602.3
Current Liabilities
Long-term Debt Due Within One Year	354.0	3.3
Noncurrent Liabilities
Long-term Debt	$ 2,320.0	$ 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	$ 12.8	$ 3.7
Fuel	33.4	40.4
Property, Plant and Equipment
Other Property, Plant and Equipment	282.4	297.7
Accumulated Depreciation and Amortization	160.2	157.3
AEP Subsidiaries [Member]
Current Assets
Other Temporary Investments	270.5	376.6
Current Liabilities
Long-term Debt Due Within One Year	393.4	410.4
Noncurrent Liabilities
Long-term Debt	$ 1,727.6	$ 1,971.4