Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Current Assets
Cash and Cash Equivalents	$ 210.5	$ 234.1
Restricted Cash	179.1	210.0
Other Temporary Investments	175.7	159.1
Fuel	441.7	341.5
Property, Plant and Equipment
Other Property, Plant and Equipment	4,452.2	4,265.0
Accumulated Depreciation and Amortization	18,439.1	17,986.1
Other Noncurrent Assets
Securitized Transition Assets	785.3	920.6
Current Liabilities
Long-term Debt Due Within One Year	1,257.4	1,698.5
Accrued Interest	241.2	231.7
Noncurrent Liabilities
Long-term Debt	$ 24,174.4	$ 21,648.2
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	513,962,056	513,450,036
Treasury Stock, Shares	20,204,160	20,204,160
AEP Subsidiaries [Member]
Current Assets
Restricted Cash	$ 179.1	$ 210.0
Other Temporary Investments	168.9	152.7
Current Liabilities
Long-term Debt Due Within One Year	554.4	406.5
Noncurrent Liabilities
Long-term Debt	819.9	1,109.2
AEP Texas Inc. [Member]
Current Assets
Cash and Cash Equivalents	0.1	3.1
Restricted Cash	125.4	156.7
Fuel	6.4	8.8
Property, Plant and Equipment
Other Property, Plant and Equipment	766.7	727.9
Accumulated Depreciation and Amortization	1,712.6	1,651.2
Other Noncurrent Assets
Securitized Transition Assets	536.9	649.1
Current Liabilities
Long-term Debt Due Within One Year	309.9	501.1
Accrued Interest	36.3	37.3
Noncurrent Liabilities
Long-term Debt	3,684.7	3,380.2
AEP Texas Inc. [Member] | AEP Texas Central Transition Funding Co [Member]
Other Noncurrent Assets
Securitized Transition Assets	528.9	636.8
Current Liabilities
Long-term Debt Due Within One Year	259.2	251.1
Accrued Interest	8.5	11.3
Noncurrent Liabilities
Long-term Debt	400.8	540.1
Appalachian Power Co [Member]
Current Assets
Cash and Cash Equivalents	2.3	4.2
Restricted Cash	25.4	25.6
Fuel	110.9	61.3
Property, Plant and Equipment
Other Property, Plant and Equipment	517.0	485.8
Accumulated Depreciation and Amortization	4,230.8	4,124.4
Other Noncurrent Assets
Securitized Transition Assets	246.6	258.7
Current Liabilities
Long-term Debt Due Within One Year	150.0	430.7
Accrued Interest	47.0	41.5
Noncurrent Liabilities
Long-term Debt	$ 4,224.8	$ 3,631.9
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	$ 1.4	$ 2.4
Fuel	39.3	37.3
Property, Plant and Equipment
Other Property, Plant and Equipment	617.0	583.8
Accumulated Depreciation and Amortization	3,227.6	3,151.6
Current Liabilities
Long-term Debt Due Within One Year	155.1	155.4
Accrued Interest	36.7	37.3
Noncurrent Liabilities
Long-term Debt	$ 2,899.4	$ 2,880.0
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	$ 76.6	$ 76.8
Ohio Power Co [Member]
Current Assets
Cash and Cash Equivalents	2.7	4.9
Restricted Cash	28.2	27.6
Property, Plant and Equipment
Other Property, Plant and Equipment	643.3	574.8
Accumulated Depreciation and Amortization	2,238.8	2,218.6
Other Noncurrent Assets
Securitized Transition Assets	1.8	12.9
Current Liabilities
Long-term Debt Due Within One Year	24.7	47.9
Noncurrent Liabilities
Long-term Debt	$ 2,113.5	$ 1,668.7
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	$ 24.6	$ 47.8
Public Service Co Of Oklahoma [Member]
Current Assets
Cash and Cash Equivalents	1.4	2.0
Fuel	10.5	12.3
Property, Plant and Equipment
Other Property, Plant and Equipment	313.5	303.5
Accumulated Depreciation and Amortization	1,527.2	1,472.9
Current Liabilities
Long-term Debt Due Within One Year	138.1	375.5
Noncurrent Liabilities
Long-term Debt	$ 1,248.2	$ 911.5
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	$ 24.0	$ 24.5
Fuel	136.6	120.5
Property, Plant and Equipment
Other Property, Plant and Equipment	698.8	762.7
Accumulated Depreciation and Amortization	2,805.2	2,808.3
Current Liabilities
Long-term Debt Due Within One Year	121.2	59.7
Accrued Interest	33.8	34.7
Noncurrent Liabilities
Long-term Debt	$ 2,536.9	$ 2,653.7
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	$ 22.2	$ 22.0
Fuel	34.9	35.7
Property, Plant and Equipment
Other Property, Plant and Equipment	210.3	276.9
Accumulated Depreciation and Amortization	$ 101.6	$ 174.6