Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues
Vertically Integrated Utilities	$ 2,381.5	$ 2,269.8
Transmission and Distribution Utilities	1,141.2	1,066.4
Generation & Marketing	477.5	558.8
Sales to AEP Affiliates	0.0	0.0
Other Revenues	48.1	38.3
TOTAL REVENUES	4,048.3	3,933.3
Expenses
Fuel and Other Consumables Used for Electric Generation	501.8	635.6
Purchased Electricity for Resale	990.3	769.6
Other Operation	726.4	623.7
Maintenance	298.5	303.5
Gain on Sale of Merchant Generation Assets	0.0	(226.5)
Depreciation and Amortization	539.7	481.9
Taxes Other Than Income Taxes	285.6	259.8
TOTAL EXPENSES	3,342.3	2,847.6
OPERATING INCOME (LOSS)	706.0	1,085.7
Other Income (Expense):
Interest and Investment Income	2.1	8.0
Carrying Costs Income	3.4	5.9
Allowance for Equity Funds Used During Construction	30.7	21.2
Non-Service Cost Components of Net Periodic Benefit Cost	32.0	11.4
Interest Expense	(234.0)	(221.8)
INCOME BEFORE INCOME TAX EXPENSE AND EQUITY EARNINGS	540.2	910.4
Income Tax Expense (Credit)	102.0	343.2
Equity Earnings (Loss) of Unconsolidated Subsidiaries	18.5	27.0
NET INCOME (LOSS)	456.7	594.2
Net Income Attributable to Noncontrolling Interests	2.3	2.0
EARNINGS ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 454.4	$ 592.2
Earnings Per Share
Weighted Average Number of Basic AEP Common Shares Outstanding	492,267,402	491,712,042
Total Basic Earnings Per Share Attributable to AEP Common Shareholders	$ 0.92	$ 1.20
Weighted Average Number of Diluted AEP Common Shares Outstanding	493,127,300	492,031,975
Total Diluted Earnings Per Share Attributable to AEP Common Shareholders	$ 0.92	$ 1.20
Common Stock, Dividends, Per Share, Declared	$ 0.62	$ 0.59
AEP Texas Inc. [Member]
Revenues
Transmission and Distribution Utilities	$ 352.4	$ 328.9
Sales to AEP Affiliates	18.2	14.1
Other Revenues	1.0	0.6
TOTAL REVENUES	371.6	343.6
Expenses
Fuel and Other Consumables Used for Electric Generation	8.9	3.0
Other Operation	117.0	108.8
Maintenance	21.5	18.4
Depreciation and Amortization	110.0	102.8
Taxes Other Than Income Taxes	32.4	28.3
TOTAL EXPENSES	289.8	261.3
OPERATING INCOME (LOSS)	81.8	82.3
Other Income (Expense):
Interest Income	0.5	1.0
Allowance for Equity Funds Used During Construction	5.5	1.8
Non-Service Cost Components of Net Periodic Benefit Cost	3.1	0.9
Interest Expense	(35.0)	(35.0)
INCOME BEFORE INCOME TAX EXPENSE AND EQUITY EARNINGS	55.9	51.0
Income Tax Expense (Credit)	9.1	17.7
NET INCOME (LOSS)	46.8	33.3
AEP Transmission Co [Member]
Revenues
Electrical Transmission Revenue	31.3	19.2
Sales to AEP Affiliates	162.1	133.4
Other Revenues	0.1	0.1
TOTAL REVENUES	193.5	152.7
Expenses
Other Operation	16.6	9.1
Maintenance	2.6	3.1
Depreciation and Amortization	30.6	23.3
Taxes Other Than Income Taxes	31.1	26.8
TOTAL EXPENSES	80.9	62.3
OPERATING INCOME (LOSS)	112.6	90.4
Other Income (Expense):
Interest Income	0.4	0.2
Allowance for Equity Funds Used During Construction	15.3	10.9
Interest Expense	(19.9)	(16.0)
INCOME BEFORE INCOME TAX EXPENSE AND EQUITY EARNINGS	108.4	85.5
Income Tax Expense (Credit)	22.5	28.5
NET INCOME (LOSS)	85.9	57.0
Appalachian Power Co [Member]
Revenues
Vertically Integrated Utilities	767.5	745.0
Sales to AEP Affiliates	49.4	42.4
Other Revenues	3.5	5.4
TOTAL REVENUES	820.4	792.8
Expenses
Fuel and Other Consumables Used for Electric Generation	69.0	167.2
Purchased Electricity for Resale	205.9	90.8
Other Operation	138.2	113.9
Maintenance	72.0	71.2
Depreciation and Amortization	108.5	100.6
Taxes Other Than Income Taxes	33.8	30.2
TOTAL EXPENSES	627.4	573.9
OPERATING INCOME (LOSS)	193.0	218.9
Other Income (Expense):
Interest Income	0.3	0.3
Carrying Costs Income	0.5	0.3
Allowance for Equity Funds Used During Construction	2.6	1.5
Non-Service Cost Components of Net Periodic Benefit Cost	4.5	1.3
Interest Expense	(47.4)	(48.1)
INCOME BEFORE INCOME TAX EXPENSE AND EQUITY EARNINGS	153.5	174.2
Income Tax Expense (Credit)	28.0	63.6
NET INCOME (LOSS)	125.5	110.6
Indiana Michigan Power Co [Member]
Revenues
Vertically Integrated Utilities	553.9	538.5
Sales to AEP Affiliates	4.7	0.6
Other Revenues - Affiliated	13.2	18.1
Other Revenues	5.0	3.3
TOTAL REVENUES	576.8	560.5
Expenses
Fuel and Other Consumables Used for Electric Generation	77.5	90.7
Purchased Electricity for Resale	55.6	37.3
Purchased Electricity from AEP Affiliates	61.4	53.9
Other Operation	146.1	137.1
Maintenance	54.5	51.4
Depreciation and Amortization	59.3	50.0
Taxes Other Than Income Taxes	25.0	22.9
TOTAL EXPENSES	479.4	443.3
OPERATING INCOME (LOSS)	97.4	117.2
Other Income (Expense):
Interest Income	0.2	1.1
Carrying Costs Income	2.4	3.4
Allowance for Equity Funds Used During Construction	1.8	2.1
Non-Service Cost Components of Net Periodic Benefit Cost	4.5	1.5
Interest Expense	(29.7)	(27.7)
INCOME BEFORE INCOME TAX EXPENSE AND EQUITY EARNINGS	76.6	97.6
Income Tax Expense (Credit)	12.4	29.2
NET INCOME (LOSS)	64.2	68.4
Ohio Power Co [Member]
Revenues
Transmission and Distribution Utilities	786.3	738.4
Sales to AEP Affiliates	3.1	5.7
Other Revenues	1.5	2.0
TOTAL REVENUES	790.9	746.1
Expenses
Purchased Electricity for Resale	205.5	188.3
Purchased Electricity from AEP Affiliates	30.2	32.0
Amortization Of Generation Deferrals	58.6	60.9
Other Operation	172.2	122.3
Maintenance	37.2	37.2
Depreciation and Amortization	64.8	57.3
Taxes Other Than Income Taxes	105.1	98.5
TOTAL EXPENSES	673.6	596.5
OPERATING INCOME (LOSS)	117.3	149.6
Other Income (Expense):
Interest Income	0.9	2.5
Carrying Costs Income	0.7	1.9
Allowance for Equity Funds Used During Construction	2.5	2.4
Non-Service Cost Components of Net Periodic Benefit Cost	3.9	1.1
Interest Expense	(25.2)	(25.0)
INCOME BEFORE INCOME TAX EXPENSE AND EQUITY EARNINGS	100.1	132.5
Income Tax Expense (Credit)	20.5	46.3
NET INCOME (LOSS)	79.6	86.2
Public Service Co Of Oklahoma [Member]
Revenues
Vertically Integrated Utilities	335.1	301.9
Sales to AEP Affiliates	1.1	1.1
Other Revenues	0.6	1.1
TOTAL REVENUES	336.8	304.1
Expenses
Fuel and Other Consumables Used for Electric Generation	48.4	12.3
Purchased Electricity for Resale	122.4	125.3
Other Operation	86.8	68.3
Maintenance	26.9	34.2
Depreciation and Amortization	36.8	33.5
Taxes Other Than Income Taxes	11.6	10.6
TOTAL EXPENSES	332.9	284.2
OPERATING INCOME (LOSS)	3.9	19.9
Other Income (Expense):
Allowance for Equity Funds Used During Construction	(0.1)	0.4
Other Nonoperating Income (Expense)	0.0	0.5
Non-Service Cost Components of Net Periodic Benefit Cost	2.2	0.9
Interest Expense	(14.7)	(13.6)
INCOME BEFORE INCOME TAX EXPENSE AND EQUITY EARNINGS	(8.6)	7.7
Income Tax Expense (Credit)	(1.4)	2.9
NET INCOME (LOSS)	(7.2)	4.8
Southwestern Electric Power Co [Member]
Revenues
Vertically Integrated Utilities	413.0	396.3
Sales to AEP Affiliates	6.1	4.6
Other Revenues	0.3	0.4
TOTAL REVENUES	419.4	401.3
Expenses
Fuel and Other Consumables Used for Electric Generation	126.8	130.9
Purchased Electricity for Resale	42.7	32.4
Other Operation	94.9	78.9
Maintenance	31.0	32.2
Depreciation and Amortization	57.4	50.8
Taxes Other Than Income Taxes	25.0	23.3
TOTAL EXPENSES	377.8	348.5
OPERATING INCOME (LOSS)	41.6	52.8
Other Income (Expense):
Interest Income	1.8	0.9
Allowance for Equity Funds Used During Construction	2.3	0.8
Non-Service Cost Components of Net Periodic Benefit Cost	2.3	0.9
Interest Expense	(32.2)	(29.9)
INCOME BEFORE INCOME TAX EXPENSE AND EQUITY EARNINGS	15.8	25.5
Income Tax Expense (Credit)	2.9	9.5
Equity Earnings (Loss) of Unconsolidated Subsidiaries	0.5	1.3
NET INCOME (LOSS)	13.4	17.3
Net Income Attributable to Noncontrolling Interests	1.6	1.0
EARNINGS ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 11.8	$ 16.3