Condensed Consolidated Balance Sheets - USD ($) $ in Millions		Sep. 30, 2017	Dec. 31, 2016
Current Assets
Cash and Cash Equivalents		$ 343.9	$ 210.5
Other Temporary Investments		310.7	331.7
Accounts Receivable:
Customers		522.7	705.1
Accrued Unbilled Revenues		187.3	158.7
Pledged Accounts Receivable - AEP Credit		967.6	972.7
Miscellaneous		99.9	118.1
Allowance for Uncollectible Accounts		(36.6)	(37.9)
Total Accounts Receivable		1,740.9	1,916.7
Fuel		354.2	423.8
Materials and Supplies		562.3	543.5
Risk Management Assets		146.1	94.5
Regulatory Asset for Under-Recovered Fuel Costs		153.5	156.6
Margin Deposits		105.7	79.9
Assets Held for Sale		0.0	1,951.2
Prepayments and Other Current Assets		350.5	325.5
TOTAL CURRENT ASSETS		4,067.8	6,033.9
Property, Plant and Equipment
Generation		20,739.3	19,848.9
Transmission		17,785.4	16,658.7
Distribution		19,589.4	18,900.8
Other Property, Plant and Equipment		3,614.1	3,444.3
Construction Work in Progress		3,710.0	3,183.9
Total Property, Plant and Equipment		65,438.2	62,036.6
Accumulated Depreciation and Amortization		17,121.7	16,397.3
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		48,316.5	45,639.3
Other Noncurrent Assets
Regulatory Assets		5,640.0	5,625.5
Securitized Assets		1,287.8	1,486.1
Spent Nuclear Fuel and Decommissioning Trusts		2,433.0	2,256.2
Goodwill		52.5	52.5
Long-term Risk Management Assets		310.4	289.1
Deferred Charges and Other Noncurrent Assets		1,856.9	2,085.1
TOTAL OTHER NONCURRENT ASSETS		11,580.6	11,794.5
TOTAL ASSETS		63,964.9	63,467.7
Current Liabilities
Accounts Payable		1,537.0	1,688.5
Short-term Debt:
Securitized Debt for Receivables - AEP Credit	[1]	750.0	673.0
Other Short-term Debt		309.3	1,040.0
Total Short-term Debt		1,059.3	1,713.0
Long-term Debt Due Within One Year		2,359.3	2,878.0
Risk Management Liabilities		69.4	53.4
Customer Deposits		346.6	343.2
Accrued Taxes		716.5	1,048.0
Accrued Interest		260.3	227.2
Regulatory Liability for Over-Recovered Fuel Costs		19.7	8.0
Liabilities Held for Sale		0.0	235.9
Other Current Liabilities		953.9	1,302.8
TOTAL CURRENT LIABILITIES		7,322.0	9,498.0
Noncurrent Liabilities
Long-term Debt		18,362.4	17,378.4
Long-term Risk Management Liabilities		352.7	316.2
Deferred Income Taxes		12,628.2	11,884.4
Regulatory Liabilities and Deferred Investment Tax Credits		3,959.6	3,751.3
Asset Retirement Obligations		1,919.3	1,830.6
Employee Benefits and Pension Obligations		468.9	614.1
Deferred Credits and Other Noncurrent Liabilities		837.0	774.6
TOTAL NONCURRENT LIABILITIES		38,528.1	36,549.6
TOTAL LIABILITIES		45,850.1	46,047.6
Rate Matters
Commitments and Contingencies
Mezzanine Equity		9.3	0.0
Equity
Common Stock		3,328.3	3,328.3
Paid-in Capital		6,384.2	6,332.6
Retained Earnings		8,532.0	7,892.4
Accumulated Other Comprehensive Income (Loss)		(175.4)	(156.3)
TOTAL COMMON SHAREHOLDER'S EQUITY		18,069.1	17,397.0
Noncontrolling Interests		36.4	23.1
TOTAL EQUITY		18,105.5	17,420.1
TOTAL LIABILITIES AND EQUITY		63,964.9	63,467.7
AEP Transmission Co [Member]
Current Assets
Cash and Cash Equivalents		0.0	0.0
Advances to Affiliates		290.9	67.1
Accounts Receivable:
Customers		19.5	11.3
Affiliated Companies		102.8	66.6
Total Accounts Receivable		122.3	77.9
Materials and Supplies		16.0	5.0
Accrued Tax Benefits		12.7	26.0
Prepayments and Other Current Assets		8.1	2.8
TOTAL CURRENT ASSETS		450.0	178.8
Property, Plant and Equipment
Transmission		4,570.9	3,973.5
Other Property, Plant and Equipment		113.5	99.4
Construction Work in Progress		1,383.1	981.3
Total Property, Plant and Equipment		6,067.5	5,054.2
Accumulated Depreciation and Amortization		151.5	99.6
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		5,916.0	4,954.6
Other Noncurrent Assets
Accounts Receivable, Related Parties, Noncurrent		13.8	0.0
Regulatory Assets		138.0	112.3
Deferred Tax Assets, Property, Plant and Equipment		29.8	102.2
Deferred Charges and Other Noncurrent Assets		1.3	1.9
TOTAL OTHER NONCURRENT ASSETS		182.9	216.4
TOTAL ASSETS		6,548.9	5,349.8
Current Liabilities
Advances from Affiliates		32.8	4.1
Accounts Payable		233.2	289.7
Affiliated Companies		50.0	43.1
Short-term Debt:
Accrued Taxes		112.5	191.8
Accrued Interest		28.9	10.5
Other Current Liabilities		10.4	10.9
TOTAL CURRENT LIABILITIES		467.8	550.1
Noncurrent Liabilities
Long-term Debt		2,550.0	1,932.0
Deferred Income Taxes		1,073.1	862.1
Regulatory Liabilities and Deferred Investment Tax Credits		60.5	44.0
Deferred Credits and Other Noncurrent Liabilities		30.1	4.0
TOTAL NONCURRENT LIABILITIES		3,713.7	2,842.1
TOTAL LIABILITIES		4,181.5	3,392.2
Rate Matters
Commitments and Contingencies
Equity
Paid-in Captial		1,640.5	1,455.0
Retained Earnings		726.9	502.6
TOTAL MEMBER'S EQUITY		2,367.4	1,957.6
TOTAL LIABILITIES AND EQUITY		6,548.9	5,349.8
Appalachian Power Co [Member]
Current Assets
Cash and Cash Equivalents		2.9	2.7
Restricted Cash for Securitized Funding		8.3	15.8
Advances to Affiliates		23.6	24.1
Accounts Receivable:
Customers		96.8	131.4
Affiliated Companies		59.5	54.4
Accrued Unbilled Revenues		41.1	52.7
Miscellaneous		1.3	0.9
Allowance for Uncollectible Accounts		(2.7)	(3.5)
Total Accounts Receivable		196.0	235.9
Fuel		96.3	112.0
Materials and Supplies		100.8	98.8
Risk Management Assets		30.3	2.6
Accrued Tax Benefits		0.4	4.2
Regulatory Asset for Under-Recovered Fuel Costs		63.5	68.4
Margin Deposits		11.8	17.5
Prepayments and Other Current Assets		18.2	9.7
TOTAL CURRENT ASSETS		552.1	591.7
Property, Plant and Equipment
Generation		6,393.7	6,332.8
Transmission		2,904.4	2,796.9
Distribution		3,703.5	3,569.1
Other Property, Plant and Equipment		409.8	373.5
Construction Work in Progress		493.5	390.3
Total Property, Plant and Equipment		13,904.9	13,462.6
Accumulated Depreciation and Amortization		3,836.7	3,636.8
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		10,068.2	9,825.8
Other Noncurrent Assets
Regulatory Assets		1,100.1	1,121.1
Securitized Assets		288.0	305.3
Long-term Risk Management Assets		0.6	0.0
Deferred Charges and Other Noncurrent Assets		113.6	133.3
TOTAL OTHER NONCURRENT ASSETS		1,502.3	1,559.7
TOTAL ASSETS		12,122.6	11,977.2
Current Liabilities
Advances from Affiliates		69.5	79.6
Accounts Payable		235.4	253.7
Affiliated Companies		75.5	82.6
Short-term Debt:
Long-term Debt Due Within One Year		149.2	503.1
Risk Management Liabilities		0.9	0.3
Customer Deposits		84.0	83.1
Accrued Taxes		64.0	107.6
Accrued Interest		71.4	40.6
Other Current Liabilities		99.2	129.5
TOTAL CURRENT LIABILITIES		849.1	1,280.1
Noncurrent Liabilities
Long-term Debt		3,830.1	3,530.8
Long-term Risk Management Liabilities		0.3	0.9
Deferred Income Taxes		2,796.7	2,672.3
Regulatory Liabilities and Deferred Investment Tax Credits		634.4	627.8
Asset Retirement Obligations		101.2	108.8
Employee Benefits and Pension Obligations		92.2	108.5
Deferred Credits and Other Noncurrent Liabilities		77.8	64.5
TOTAL NONCURRENT LIABILITIES		7,532.7	7,113.6
TOTAL LIABILITIES		8,381.8	8,393.7
Rate Matters
Commitments and Contingencies
Equity
Common Stock		260.4	260.4
Paid-in Capital		1,828.7	1,828.7
Retained Earnings		1,661.5	1,502.8
Accumulated Other Comprehensive Income (Loss)		(9.8)	(8.4)
TOTAL EQUITY		3,740.8	3,583.5
TOTAL LIABILITIES AND EQUITY		12,122.6	11,977.2
Indiana Michigan Power Co [Member]
Current Assets
Cash and Cash Equivalents		1.3	1.2
Advances to Affiliates		12.6	12.5
Accounts Receivable:
Customers		42.1	60.2
Affiliated Companies		42.8	51.0
Accrued Unbilled Revenues		8.4	1.5
Miscellaneous		1.1	0.7
Allowance for Uncollectible Accounts		(0.3)	0.0
Total Accounts Receivable		94.1	113.4
Fuel		32.3	32.3
Materials and Supplies		156.5	150.8
Risk Management Assets		11.6	3.5
Accrued Tax Benefits		34.5	37.7
Regulatory Asset for Under-Recovered Fuel Costs		12.3	26.1
Accrued Reimbursement of Spent Nuclear Fuel Costs		11.0	22.1
Prepayments and Other Current Assets		26.9	19.9
TOTAL CURRENT ASSETS		393.1	419.5
Property, Plant and Equipment
Generation		4,399.9	4,056.1
Transmission		1,491.4	1,472.8
Distribution		2,000.1	1,899.3
Other Property, Plant and Equipment		555.9	550.2
Construction Work in Progress		478.9	654.2
Total Property, Plant and Equipment		8,926.2	8,632.6
Accumulated Depreciation and Amortization		3,022.5	3,005.1
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		5,903.7	5,627.5
Other Noncurrent Assets
Regulatory Assets		941.0	916.6
Spent Nuclear Fuel and Decommissioning Trusts		2,433.0	2,256.2
Long-term Risk Management Assets		0.5	0.0
Deferred Charges and Other Noncurrent Assets		95.9	121.5
TOTAL OTHER NONCURRENT ASSETS		3,470.4	3,294.3
TOTAL ASSETS		9,767.2	9,341.3
Current Liabilities
Advances from Affiliates		177.5	215.2
Accounts Payable		168.6	179.0
Affiliated Companies		72.2	75.6
Short-term Debt:
Long-term Debt Due Within One Year		462.1	209.3
Risk Management Liabilities		2.0	0.3
Customer Deposits		37.3	34.3
Accrued Taxes		43.8	77.2
Accrued Interest		14.3	31.7
Obligations Under Capital Leases		7.3	9.4
Other Current Liabilities		114.3	123.4
TOTAL CURRENT LIABILITIES		1,099.4	955.4
Noncurrent Liabilities
Long-term Debt		2,196.4	2,262.1
Long-term Risk Management Liabilities		0.2	0.8
Deferred Income Taxes		1,681.8	1,527.4
Regulatory Liabilities and Deferred Investment Tax Credits		1,169.6	1,065.5
Asset Retirement Obligations		1,307.4	1,257.9
Deferred Credits and Other Noncurrent Liabilities		109.5	120.4
TOTAL NONCURRENT LIABILITIES		6,464.9	6,234.1
TOTAL LIABILITIES		7,564.3	7,189.5
Rate Matters
Commitments and Contingencies
Equity
Common Stock		56.6	56.6
Paid-in Capital		980.9	980.9
Retained Earnings		1,180.6	1,130.5
Accumulated Other Comprehensive Income (Loss)		(15.2)	(16.2)
TOTAL EQUITY		2,202.9	2,151.8
TOTAL LIABILITIES AND EQUITY		9,767.2	9,341.3
Ohio Power Co [Member]
Current Assets
Cash and Cash Equivalents		3.1	3.1
Restricted Cash for Securitized Funding		15.6	27.2
Advances to Affiliates		0.0	24.2
Accounts Receivable:
Customers		27.1	51.1
Affiliated Companies		72.0	66.3
Accrued Unbilled Revenues		24.2	21.0
Miscellaneous		1.1	0.9
Allowance for Uncollectible Accounts		(0.4)	(0.4)
Total Accounts Receivable		124.0	138.9
Materials and Supplies		42.8	45.9
Emission Allowances		23.6	20.4
Risk Management Assets		0.2	0.2
Accrued Tax Benefits		15.4	0.1
Prepayments and Other Current Assets		28.1	10.9
TOTAL CURRENT ASSETS		252.8	270.9
Property, Plant and Equipment
Transmission		2,349.5	2,319.2
Distribution		4,575.0	4,457.2
Other Property, Plant and Equipment		487.9	443.7
Construction Work in Progress		350.7	221.5
Total Property, Plant and Equipment		7,763.1	7,441.6
Accumulated Depreciation and Amortization		2,182.8	2,116.0
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		5,580.3	5,325.6
Other Noncurrent Assets
Notes Receivable - Affiliated		32.3	32.3
Regulatory Assets		1,014.7	1,107.5
Securitized Assets		43.7	62.1
Deferred Charges and Other Noncurrent Assets		131.2	295.5
TOTAL OTHER NONCURRENT ASSETS		1,221.9	1,497.4
TOTAL ASSETS		7,055.0	7,093.9
Current Liabilities
Advances from Affiliates		167.6	0.0
Accounts Payable		157.8	175.4
Affiliated Companies		95.3	95.6
Short-term Debt:
Long-term Debt Due Within One Year		397.0	46.4
Risk Management Liabilities		7.6	5.9
Customer Deposits		62.9	71.0
Accrued Taxes		251.3	520.3
Accrued Interest		38.3	31.2
Other Current Liabilities		166.3	236.0
TOTAL CURRENT LIABILITIES		1,344.1	1,181.8
Noncurrent Liabilities
Long-term Debt		1,321.9	1,717.5
Long-term Risk Management Liabilities		130.9	113.1
Deferred Income Taxes		1,460.7	1,346.1
Regulatory Liabilities and Deferred Investment Tax Credits		519.3	506.2
Employee Benefits and Pension Obligations		19.3	27.8
Deferred Credits and Other Noncurrent Liabilities		41.0	83.9
TOTAL NONCURRENT LIABILITIES		3,493.1	3,794.6
TOTAL LIABILITIES		4,837.2	4,976.4
Rate Matters
Commitments and Contingencies
Equity
Common Stock		321.2	321.2
Paid-in Capital		838.8	838.8
Retained Earnings		1,055.6	954.5
Accumulated Other Comprehensive Income (Loss)		2.2	3.0
TOTAL EQUITY		2,217.8	2,117.5
TOTAL LIABILITIES AND EQUITY		7,055.0	7,093.9
Public Service Co Of Oklahoma [Member]
Current Assets
Cash and Cash Equivalents		2.1	1.5
Accounts Receivable:
Customers		17.8	27.5
Affiliated Companies		31.8	26.8
Miscellaneous		3.2	4.4
Allowance for Uncollectible Accounts		(0.1)	(0.2)
Total Accounts Receivable		52.7	58.5
Fuel		11.9	22.9
Materials and Supplies		42.1	44.6
Risk Management Assets		4.7	0.8
Accrued Tax Benefits		27.0	27.3
Regulatory Asset for Under-Recovered Fuel Costs		36.9	33.8
Prepayments and Other Current Assets		14.4	6.0
TOTAL CURRENT ASSETS		191.8	195.4
Property, Plant and Equipment
Generation		1,573.8	1,559.3
Transmission		852.5	832.8
Distribution		2,414.1	2,322.4
Other Property, Plant and Equipment		286.3	233.2
Construction Work in Progress		114.0	148.2
Total Property, Plant and Equipment		5,240.7	5,095.9
Accumulated Depreciation and Amortization		1,382.8	1,272.7
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		3,857.9	3,823.2
Other Noncurrent Assets
Regulatory Assets		393.6	340.2
Employee Benefits and Pension Assets		16.0	10.4
Deferred Charges and Other Noncurrent Assets		19.2	10.0
TOTAL OTHER NONCURRENT ASSETS		428.8	360.6
TOTAL ASSETS		4,478.5	4,379.2
Current Liabilities
Advances from Affiliates		118.0	52.0
Accounts Payable		93.8	116.3
Affiliated Companies		43.0	56.2
Short-term Debt:
Long-term Debt Due Within One Year		0.5	0.5
Customer Deposits		53.1	49.7
Accrued Taxes		40.8	21.0
Accrued Interest		19.5	13.9
Provision for Refund		4.1	46.1
Other Current Liabilities		38.5	47.8
TOTAL CURRENT LIABILITIES		411.3	403.5
Noncurrent Liabilities
Long-term Debt		1,285.9	1,285.5
Deferred Income Taxes		1,152.5	1,058.8
Regulatory Liabilities and Deferred Investment Tax Credits		320.9	339.7
Asset Retirement Obligations		54.5	52.8
Deferred Credits and Other Noncurrent Liabilities		21.0	24.8
TOTAL NONCURRENT LIABILITIES		2,834.8	2,761.6
TOTAL LIABILITIES		3,246.1	3,165.1
Rate Matters
Commitments and Contingencies
Equity
Common Stock		157.2	157.2
Paid-in Capital		364.0	364.0
Retained Earnings		708.4	689.5
Accumulated Other Comprehensive Income (Loss)		2.8	3.4
TOTAL EQUITY		1,232.4	1,214.1
TOTAL LIABILITIES AND EQUITY		4,478.5	4,379.2
Southwestern Electric Power Co [Member]
Current Assets
Cash and Cash Equivalents		2.2	10.3
Advances to Affiliates		2.0	169.8
Accounts Receivable:
Customers		23.5	48.5
Affiliated Companies		37.6	29.3
Miscellaneous		20.8	17.5
Allowance for Uncollectible Accounts		(1.5)	(1.2)
Total Accounts Receivable		80.4	94.1
Fuel		93.1	107.1
Materials and Supplies		68.8	68.4
Risk Management Assets		12.5	0.9
Accrued Tax Benefits		14.5	51.5
Regulatory Asset for Under-Recovered Fuel Costs		13.6	8.4
Prepayments and Other Current Assets		35.5	35.5
TOTAL CURRENT ASSETS		322.6	546.0
Property, Plant and Equipment
Generation		4,632.9	4,607.6
Transmission		1,656.4	1,584.2
Distribution		2,084.2	2,020.6
Other Property, Plant and Equipment		701.6	670.4
Construction Work in Progress		145.2	113.8
Total Property, Plant and Equipment		9,220.3	8,996.6
Accumulated Depreciation and Amortization		2,670.5	2,567.1
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		6,549.8	6,429.5
Other Noncurrent Assets
Regulatory Assets		566.4	551.2
Long-term Risk Management Assets		0.7	0.0
Deferred Charges and Other Noncurrent Assets		116.4	99.9
TOTAL OTHER NONCURRENT ASSETS		683.5	651.1
TOTAL ASSETS		7,555.9	7,626.6
Current Liabilities
Advances from Affiliates		48.3	0.0
Accounts Payable		120.9	117.5
Affiliated Companies		38.5	68.5
Short-term Debt:
Other Short-term Debt		14.3	0.0
Long-term Debt Due Within One Year		385.4	353.7
Risk Management Liabilities		0.1	0.3
Customer Deposits		61.6	62.1
Accrued Taxes		73.0	40.9
Accrued Interest		25.1	45.1
Obligations Under Capital Leases		11.4	11.8
Other Current Liabilities		77.5	83.9
TOTAL CURRENT LIABILITIES		856.1	783.8
Noncurrent Liabilities
Long-term Debt		2,056.1	2,325.4
Deferred Income Taxes		1,694.5	1,606.9
Regulatory Liabilities and Deferred Investment Tax Credits		441.3	438.9
Asset Retirement Obligations		159.0	147.1
Employee Benefits and Pension Obligations		19.9	34.1
Obligations Under Capital Leases		60.2	65.5
Deferred Credits and Other Noncurrent Liabilities		11.7	9.7
TOTAL NONCURRENT LIABILITIES		4,442.7	4,627.6
TOTAL LIABILITIES		5,298.8	5,411.4
Rate Matters
Commitments and Contingencies
Equity
Common Stock		135.7	135.7
Paid-in Capital		676.6	676.6
Retained Earnings		1,443.3	1,411.9
Accumulated Other Comprehensive Income (Loss)		(8.8)	(9.4)
TOTAL COMMON SHAREHOLDER'S EQUITY		2,246.8	2,214.8
Noncontrolling Interests		10.3	0.4
TOTAL EQUITY		2,257.1	2,215.2
TOTAL LIABILITIES AND EQUITY		$ 7,555.9	$ 7,626.6

[1] Amount of securitized debt for receivables as accounted for under the “Transfers and Servicing” accounting guidance.