Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Current Assets
Cash and Cash Equivalents	$ 172.4	$ 210.5
Other Temporary Investments	317.6	331.7
Fuel	427.2	423.8
Property, Plant and Equipment
Other Property, Plant and Equipment	3,595.6	3,444.3
Accumulated Depreciation and Amortization	16,907.6	16,397.3
Current Liabilities
Long-term Debt Due Within One Year	2,755.0	2,878.0
Noncurrent Liabilities
Long-term Debt	$ 16,796.9	$ 17,378.4
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	512,048,663	512,048,520
Treasury Stock, Shares	20,211,575	20,336,592
Appalachian Power Co [Member]
Current Assets
Cash and Cash Equivalents	$ 2.6	$ 2.7
Fuel	110.4	112.0
Property, Plant and Equipment
Other Property, Plant and Equipment	403.2	373.5
Accumulated Depreciation and Amortization	3,762.8	3,636.8
Current Liabilities
Long-term Debt Due Within One Year	149.0	503.1
Noncurrent Liabilities
Long-term Debt	$ 3,841.5	$ 3,530.8
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	$ 1.1	$ 1.2
Fuel	41.5	32.3
Property, Plant and Equipment
Other Property, Plant and Equipment	571.6	550.2
Accumulated Depreciation and Amortization	3,014.1	3,005.1
Current Liabilities
Long-term Debt Due Within One Year	479.8	209.3
Noncurrent Liabilities
Long-term Debt	$ 2,211.6	$ 2,262.1
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	$ 101.4	$ 130.9
Ohio Power Co [Member]
Current Assets
Cash and Cash Equivalents	2.2	3.1
Property, Plant and Equipment
Other Property, Plant and Equipment	482.2	443.7
Accumulated Depreciation and Amortization	2,164.3	2,116.0
Current Liabilities
Long-term Debt Due Within One Year	396.8	46.4
Noncurrent Liabilities
Long-term Debt	$ 1,345.7	$ 1,717.5
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	$ 46.7	$ 46.3
Noncurrent Liabilities
Long-term Debt	71.5	93.9
Public Service Co Of Oklahoma [Member]
Current Assets
Cash and Cash Equivalents	1.4	1.5
Fuel	15.5	22.9
Property, Plant and Equipment
Other Property, Plant and Equipment	283.9	233.2
Accumulated Depreciation and Amortization	1,362.9	1,272.7
Current Liabilities
Long-term Debt Due Within One Year	0.5	0.5
Noncurrent Liabilities
Long-term Debt	$ 1,285.8	$ 1,285.5
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	$ 1.7	$ 10.3
Fuel	103.1	107.1
Property, Plant and Equipment
Other Property, Plant and Equipment	699.3	670.4
Accumulated Depreciation and Amortization	2,634.4	2,567.1
Current Liabilities
Long-term Debt Due Within One Year	385.4	353.7
Noncurrent Liabilities
Long-term Debt	$ 2,057.3	$ 2,325.4
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	$ 0.0	$ 8.7
Fuel	44.1	34.3
Property, Plant and Equipment
Other Property, Plant and Equipment	268.9	267.5
Accumulated Depreciation and Amortization	161.8	155.6
AEP Subsidiaries [Member]
Current Assets
Other Temporary Investments	309.0	322.5
Current Liabilities
Long-term Debt Due Within One Year	404.6	427.5
Noncurrent Liabilities
Long-term Debt	$ 1,552.2	$ 1,737.5