Condensed Consolidated Balance Sheets - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Current Assets
Cash and Cash Equivalents		$ 183.4	$ 214.6
Restricted Cash		133.1	198.0
Other Temporary Investments		167.9	161.7
Accounts Receivable:
Customers		635.6	643.9
Accrued Unbilled Revenues		213.4	230.2
Pledged Accounts Receivable - AEP Credit		975.3	954.2
Miscellaneous		66.5	101.2
Allowance for Uncollectible Accounts		(39.3)	(38.5)
Total Accounts Receivable		1,851.5	1,891.0
Fuel		359.6	387.7
Materials and Supplies		563.2	565.5
Risk Management Assets		89.6	126.2
Regulatory Asset for Under-Recovered Fuel Costs		352.3	292.5
Margin Deposits		154.2	105.5
Prepayments and Other Current Assets		280.2	310.4
TOTAL CURRENT ASSETS		4,135.0	4,253.1
Property, Plant and Equipment
Generation		20,824.0	20,760.5
Transmission		19,239.9	18,972.5
Distribution		20,160.5	19,868.5
Other Property, Plant and Equipment		3,812.5	3,706.3
Construction Work in Progress		4,759.4	4,120.7
Total Property, Plant and Equipment		68,796.3	67,428.5
Accumulated Depreciation and Amortization		17,431.2	17,167.0
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		51,365.1	50,261.5
Other Noncurrent Assets
Regulatory Assets		3,516.9	3,587.6
Securitized Assets		1,146.6	1,211.2
Spent Nuclear Fuel and Decommissioning Trusts		2,510.6	2,527.6
Goodwill		52.5	52.5
Long-term Risk Management Assets		271.2	282.1
Deferred Charges and Other Noncurrent Assets		2,611.6	2,553.5
TOTAL OTHER NONCURRENT ASSETS		10,109.4	10,214.5
TOTAL ASSETS		65,609.5	64,729.1
Current Liabilities
Accounts Payable		1,449.6	2,065.3
Short-term Debt:
Securitized Debt for Receivables - AEP Credit	[1]	750.0	718.0
Other Short-term Debt		1,908.8	920.6
Total Short-term Debt		2,658.8	1,638.6
Long-term Debt Due Within One Year		2,616.1	1,753.7
Risk Management Liabilities		57.1	61.6
Customer Deposits		365.5	357.0
Accrued Taxes		1,081.4	1,115.5
Accrued Interest		273.1	234.5
Regulatory Liability for Over-Recovered Fuel Costs		9.8	11.9
Other Current Liabilities		960.0	1,033.2
TOTAL CURRENT LIABILITIES		9,471.4	8,271.3
Noncurrent Liabilities
Long-term Debt		18,844.9	19,419.6
Long-term Debt - Affiliated		0.0	0.0
Long-term Risk Management Liabilities		282.7	322.0
Deferred Income Taxes		6,943.9	6,813.9
Regulatory Liabilities and Deferred Investment Tax Credits		8,394.5	8,422.3
Asset Retirement Obligations		1,933.7	1,925.5
Employee Benefits and Pension Obligations		330.9	398.1
Deferred Credits and Other Noncurrent Liabilities		808.2	830.9
TOTAL NONCURRENT LIABILITIES		37,538.8	38,132.3
TOTAL LIABILITIES		47,010.2	46,403.6
Rate Matters
Commitments and Contingencies
Redeemable Noncontrolling Interest		70.7	0.0
Contingently Redeemable Performance Share Awards		17.0	11.9
Total Mezzanine Equity		87.7	11.9
Equity
Common Stock		3,332.7	3,329.4
Paid-in Capital		6,444.5	6,398.7
Retained Earnings		8,801.5	8,626.7
Accumulated Other Comprehensive Income (Loss)		(95.4)	(67.8)
TOTAL COMMON SHAREHOLDER'S EQUITY		18,483.3	18,287.0
Noncontrolling Interests		28.3	26.6
TOTAL EQUITY		18,511.6	18,313.6
TOTAL LIABILITIES AND EQUITY		65,609.5	64,729.1
AEP Texas Inc. [Member]
Current Assets
Cash and Cash Equivalents		0.1	2.0
Restricted Cash		107.1	155.2
Advances to Affiliates		8.1	111.9
Accounts Receivable:
Customers		117.7	105.3
Affiliated Companies		9.0	12.3
Accrued Unbilled Revenues		65.7	75.8
Miscellaneous		0.3	1.3
Allowance for Uncollectible Accounts		(0.5)	(0.7)
Total Accounts Receivable		192.2	194.0
Fuel		6.4	3.6
Materials and Supplies		49.4	52.0
Risk Management Assets		0.3	0.5
Accrued Tax Benefits		66.4	41.0
Prepayments and Other Current Assets		5.8	3.6
TOTAL CURRENT ASSETS		435.8	563.8
Property, Plant and Equipment
Generation		350.9	350.7
Transmission		3,097.6	3,053.6
Distribution		3,854.2	3,718.6
Other Property, Plant and Equipment		475.4	461.0
Construction Work in Progress		951.6	835.7
Total Property, Plant and Equipment		8,729.7	8,419.6
Accumulated Depreciation and Amortization		1,617.4	1,594.5
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		7,112.3	6,825.1
Other Noncurrent Assets
Regulatory Assets		379.4	378.7
Securitized Assets		838.9	891.2
Deferred Charges and Other Noncurrent Assets		134.0	114.8
TOTAL OTHER NONCURRENT ASSETS		1,352.3	1,384.7
TOTAL ASSETS		8,900.4	8,773.6
Current Liabilities
Advances from Affiliates		232.7	0.0
Accounts Payable		209.0	379.4
Affiliated Companies		22.7	30.2
Short-term Debt:
Long-term Debt Due Within One Year		273.1	266.1
Accrued Taxes		89.7	77.2
Accrued Interest		48.0	42.2
Other Current Liabilities		70.7	76.4
TOTAL CURRENT LIABILITIES		945.9	871.5
Noncurrent Liabilities
Long-term Debt		3,280.2	3,383.2
Deferred Income Taxes		913.1	913.1
Regulatory Liabilities and Deferred Investment Tax Credits		1,320.2	1,320.5
Oklaunion Purchase Power Agreement		51.8	52.0
Deferred Credits and Other Noncurrent Liabilities		73.1	63.4
TOTAL NONCURRENT LIABILITIES		5,638.4	5,732.2
TOTAL LIABILITIES		6,584.3	6,603.7
Rate Matters
Commitments and Contingencies
Equity
Paid-in Capital		1,157.9	1,057.9
Retained Earnings		1,173.2	1,124.6
Accumulated Other Comprehensive Income (Loss)		(15.0)	(12.6)
TOTAL EQUITY		2,316.1	2,169.9
TOTAL LIABILITIES AND EQUITY		8,900.4	8,773.6
AEP Transmission Co [Member]
Current Assets
Cash and Cash Equivalents		0.0	0.0
Advances to Affiliates		32.1	146.3
Accounts Receivable:
Customers		20.5	19.1
Affiliated Companies		102.0	93.2
Miscellaneous		1.2	1.3
Total Accounts Receivable		123.7	113.6
Materials and Supplies		15.5	13.6
Accrued Tax Benefits		40.1	46.6
Prepayments and Other Current Assets		2.8	7.6
TOTAL CURRENT ASSETS		214.2	327.7
Property, Plant and Equipment
Transmission		5,458.3	5,336.1
Other Property, Plant and Equipment		137.1	131.4
Construction Work in Progress		1,512.6	1,312.7
Total Property, Plant and Equipment		7,108.0	6,780.2
Accumulated Depreciation and Amortization		192.7	170.4
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		6,915.3	6,609.8
Other Noncurrent Assets
Regulatory Assets		8.9	11.7
Deferred Tax Assets, Property, Plant and Equipment		100.5	117.8
Deferred Charges and Other Noncurrent Assets		1.0	1.1
TOTAL OTHER NONCURRENT ASSETS		110.4	130.6
TOTAL ASSETS		7,239.9	7,068.1
Current Liabilities
Advances from Affiliates		282.1	15.7
Accounts Payable		210.5	473.2
Affiliated Companies		41.3	52.9
Short-term Debt:
Long-term Debt Due Within One Year		50.0	50.0
Accrued Taxes		185.3	225.4
Accrued Interest		38.3	15.0
Customer Refund Liability, Current		47.6	0.0
Other Current Liabilities		2.6	4.1
TOTAL CURRENT LIABILITIES		857.7	836.3
Noncurrent Liabilities
Long-term Debt		2,500.7	2,500.4
Deferred Income Taxes		621.3	601.7
Regulatory Liabilities and Deferred Investment Tax Credits		497.2	493.7
Deferred Credits and Other Noncurrent Liabilities		6.8	30.7
TOTAL NONCURRENT LIABILITIES		3,626.0	3,626.5
TOTAL LIABILITIES		4,483.7	4,462.8
Rate Matters
Commitments and Contingencies
Equity
Members' Capital		1,881.6	1,816.6
Retained Earnings		874.6	788.7
Members' Equity		2,756.2	2,605.3
TOTAL LIABILITIES AND EQUITY		7,239.9	7,068.1
Appalachian Power Co [Member]
Current Assets
Cash and Cash Equivalents		1.2	2.9
Restricted Cash		10.1	16.3
Advances to Affiliates		23.5	23.5
Accounts Receivable:
Customers		137.9	123.1
Affiliated Companies		67.6	69.3
Accrued Unbilled Revenues		75.1	74.1
Miscellaneous		1.0	1.1
Allowance for Uncollectible Accounts		(3.5)	(3.7)
Total Accounts Receivable		278.1	263.9
Fuel		72.1	89.3
Materials and Supplies		97.4	99.5
Risk Management Assets		8.0	24.9
Regulatory Asset for Under-Recovered Fuel Costs		179.5	88.8
Margin Deposits		32.1	14.4
Prepayments and Other Current Assets		11.2	12.7
TOTAL CURRENT ASSETS		713.2	636.2
Property, Plant and Equipment
Generation		6,466.9	6,446.9
Transmission		3,032.5	3,019.9
Distribution		3,795.8	3,763.8
Other Property, Plant and Equipment		440.2	427.9
Construction Work in Progress		558.8	483.0
Total Property, Plant and Equipment		14,294.2	14,141.5
Accumulated Depreciation and Amortization		3,956.8	3,896.4
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		10,337.4	10,245.1
Other Noncurrent Assets
Regulatory Assets		552.3	573.9
Securitized Assets		276.4	282.3
Long-term Risk Management Assets		2.6	1.1
Deferred Charges and Other Noncurrent Assets		195.1	190.0
TOTAL OTHER NONCURRENT ASSETS		1,026.4	1,047.3
TOTAL ASSETS		12,077.0	11,928.6
Current Liabilities
Advances from Affiliates		245.9	186.0
Accounts Payable		218.1	264.9
Affiliated Companies		88.1	92.7
Short-term Debt:
Long-term Debt Due Within One Year		249.5	249.2
Risk Management Liabilities		0.6	1.3
Customer Deposits		86.5	86.1
Accrued Taxes		119.0	94.5
Accrued Interest		62.9	40.5
Other Current Liabilities		111.3	109.0
TOTAL CURRENT LIABILITIES		1,181.9	1,124.2
Noncurrent Liabilities
Long-term Debt		3,719.8	3,730.9
Long-term Risk Management Liabilities		0.4	0.2
Deferred Income Taxes		1,586.0	1,565.7
Regulatory Liabilities and Deferred Investment Tax Credits		1,444.3	1,454.9
Asset Retirement Obligations		98.4	100.2
Employee Benefits and Pension Obligations		68.6	73.3
Deferred Credits and Other Noncurrent Liabilities		88.2	74.7
TOTAL NONCURRENT LIABILITIES		7,005.7	6,999.9
TOTAL LIABILITIES		8,187.6	8,124.1
Rate Matters
Commitments and Contingencies
Equity
Common Stock		260.4	260.4
Paid-in Capital		1,828.7	1,828.7
Retained Earnings		1,799.7	1,714.1
Accumulated Other Comprehensive Income (Loss)		0.6	1.3
TOTAL EQUITY		3,889.4	3,804.5
TOTAL LIABILITIES AND EQUITY		12,077.0	11,928.6
Indiana Michigan Power Co [Member]
Current Assets
Cash and Cash Equivalents		0.6	1.3
Advances to Affiliates		12.5	12.4
Accounts Receivable:
Customers		48.7	56.4
Affiliated Companies		49.9	50.0
Accrued Unbilled Revenues		8.1	7.3
Miscellaneous		5.4	2.0
Allowance for Uncollectible Accounts		0.0	(0.1)
Total Accounts Receivable		112.1	115.6
Fuel		35.2	31.4
Materials and Supplies		161.6	160.6
Risk Management Assets		3.3	7.6
Accrued Tax Benefits		65.0	58.4
Regulatory Asset for Under-Recovered Fuel Costs		12.4	15.0
Accrued Reimbursement of Spent Nuclear Fuel Costs		6.2	10.8
Margin Deposits		25.6	11.5
Prepayments and Other Current Assets		13.6	9.4
TOTAL CURRENT ASSETS		448.1	434.0
Property, Plant and Equipment
Generation		4,464.5	4,445.9
Transmission		1,523.5	1,504.0
Distribution		2,097.3	2,069.3
Other Property, Plant and Equipment		610.9	595.2
Construction Work in Progress		503.5	460.2
Total Property, Plant and Equipment		9,199.7	9,074.6
Accumulated Depreciation and Amortization		3,073.1	3,024.2
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		6,126.6	6,050.4
Other Noncurrent Assets
Regulatory Assets		589.2	579.4
Spent Nuclear Fuel and Decommissioning Trusts		2,510.6	2,527.6
Long-term Risk Management Assets		2.0	0.7
Deferred Charges and Other Noncurrent Assets		168.4	179.9
TOTAL OTHER NONCURRENT ASSETS		3,270.2	3,287.6
TOTAL ASSETS		9,844.9	9,772.0
Current Liabilities
Advances from Affiliates		314.1	211.6
Accounts Payable		164.8	154.5
Affiliated Companies		81.4	98.3
Short-term Debt:
Long-term Debt Due Within One Year		941.5	474.7
Risk Management Liabilities		3.8	3.5
Customer Deposits		38.0	37.7
Accrued Taxes		89.6	81.3
Accrued Interest		14.8	37.5
Obligations Under Capital Leases		5.8	5.8
Other Current Liabilities		102.7	106.4
TOTAL CURRENT LIABILITIES		1,756.5	1,211.3
Noncurrent Liabilities
Long-term Debt		1,775.7	2,270.4
Long-term Risk Management Liabilities		0.2	0.1
Deferred Income Taxes		978.3	953.8
Regulatory Liabilities and Deferred Investment Tax Credits		1,660.2	1,708.7
Asset Retirement Obligations		1,336.0	1,321.6
Deferred Credits and Other Noncurrent Liabilities		91.7	88.5
TOTAL NONCURRENT LIABILITIES		5,842.1	6,343.1
TOTAL LIABILITIES		7,598.6	7,554.4
Rate Matters
Commitments and Contingencies
Equity
Common Stock		56.6	56.6
Paid-in Capital		980.9	980.9
Retained Earnings		1,223.2	1,192.2
Accumulated Other Comprehensive Income (Loss)		(14.4)	(12.1)
TOTAL EQUITY		2,246.3	2,217.6
TOTAL LIABILITIES AND EQUITY		9,844.9	9,772.0
Ohio Power Co [Member]
Current Assets
Cash and Cash Equivalents		1.4	3.1
Restricted Cash		15.9	26.6
Advances to Affiliates		200.4	0.0
Accounts Receivable:
Customers		42.0	67.8
Affiliated Companies		60.4	70.2
Accrued Unbilled Revenues		27.2	29.7
Miscellaneous		1.2	1.9
Allowance for Uncollectible Accounts		(0.6)	(0.6)
Total Accounts Receivable		130.2	169.0
Materials and Supplies		41.2	41.9
Renewable Energy Credits		24.8	25.0
Risk Management Assets		0.4	0.6
Regulatory Asset for Under-Recovered Fuel Costs		89.3	115.9
Prepayments and Other Current Assets		27.1	15.8
TOTAL CURRENT ASSETS		530.7	397.9
Property, Plant and Equipment
Transmission		2,440.5	2,419.2
Distribution		4,669.3	4,626.4
Other Property, Plant and Equipment		518.9	495.9
Construction Work in Progress		432.0	410.1
Total Property, Plant and Equipment		8,060.7	7,951.6
Accumulated Depreciation and Amortization		2,205.7	2,184.8
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		5,855.0	5,766.8
Other Noncurrent Assets
Regulatory Assets		597.6	652.8
Securitized Assets		31.4	37.7
Deferred Charges and Other Noncurrent Assets		342.0	406.5
TOTAL OTHER NONCURRENT ASSETS		971.0	1,097.0
TOTAL ASSETS		7,356.7	7,261.7
Current Liabilities
Advances from Affiliates		0.0	87.8
Accounts Payable		159.9	205.8
Affiliated Companies		105.5	118.2
Short-term Debt:
Long-term Debt Due Within One Year		397.5	397.0
Risk Management Liabilities		5.3	6.4
Customer Deposits		76.5	69.2
Accrued Taxes		418.5	512.5
Accrued Interest		38.7	31.0
Other Current Liabilities		161.2	165.9
TOTAL CURRENT LIABILITIES		1,363.1	1,593.8
Noncurrent Liabilities
Long-term Debt		1,692.2	1,322.3
Long-term Risk Management Liabilities		93.2	126.0
Deferred Income Taxes		759.0	762.9
Regulatory Liabilities and Deferred Investment Tax Credits		1,120.8	1,100.2
Deferred Credits and Other Noncurrent Liabilities		50.9	46.2
TOTAL NONCURRENT LIABILITIES		3,716.1	3,357.6
TOTAL LIABILITIES		5,079.2	4,951.4
Rate Matters
Commitments and Contingencies
Equity
Common Stock		321.2	321.2
Paid-in Capital		838.8	838.8
Retained Earnings		1,115.5	1,148.4
Accumulated Other Comprehensive Income (Loss)		2.0	1.9
TOTAL EQUITY		2,277.5	2,310.3
TOTAL LIABILITIES AND EQUITY		7,356.7	7,261.7
Public Service Co Of Oklahoma [Member]
Current Assets
Cash and Cash Equivalents		0.6	1.6
Accounts Receivable:
Customers		30.9	32.5
Affiliated Companies		27.7	32.9
Miscellaneous		3.9	4.1
Allowance for Uncollectible Accounts		0.0	(0.1)
Total Accounts Receivable		62.5	69.4
Fuel		13.0	12.5
Materials and Supplies		43.2	42.0
Risk Management Assets		2.9	6.4
Accrued Tax Benefits		30.2	28.1
Regulatory Asset for Under-Recovered Fuel Costs		22.7	36.7
Prepayments and Other Current Assets		7.5	8.6
TOTAL CURRENT ASSETS		182.6	205.3
Property, Plant and Equipment
Generation		1,572.4	1,577.2
Transmission		862.0	858.8
Distribution		2,475.5	2,445.1
Other Property, Plant and Equipment		297.0	287.4
Construction Work in Progress		110.3	111.3
Total Property, Plant and Equipment		5,317.2	5,279.8
Accumulated Depreciation and Amortization		1,415.5	1,393.6
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		3,901.7	3,886.2
Other Noncurrent Assets
Regulatory Assets		366.8	368.1
Employee Benefits and Pension Assets		40.4	40.0
Deferred Charges and Other Noncurrent Assets		34.2	8.7
TOTAL OTHER NONCURRENT ASSETS		441.4	416.8
TOTAL ASSETS		4,525.7	4,508.3
Current Liabilities
Advances from Affiliates		179.1	149.6
Accounts Payable		88.7	102.4
Affiliated Companies		51.5	48.0
Short-term Debt:
Long-term Debt Due Within One Year		0.5	0.5
Customer Deposits		54.5	54.1
Accrued Taxes		42.1	22.6
Accrued Interest		19.3	14.1
Other Current Liabilities		34.8	44.7
TOTAL CURRENT LIABILITIES		470.5	436.0
Noncurrent Liabilities
Long-term Debt		1,286.2	1,286.0
Deferred Income Taxes		639.6	642.0
Regulatory Liabilities and Deferred Investment Tax Credits		851.5	853.5
Asset Retirement Obligations		53.7	53.0
Deferred Credits and Other Noncurrent Liabilities		28.3	22.5
TOTAL NONCURRENT LIABILITIES		2,859.3	2,857.0
TOTAL LIABILITIES		3,329.8	3,293.0
Rate Matters
Commitments and Contingencies
Equity
Common Stock		157.2	157.2
Paid-in Capital		364.0	364.0
Retained Earnings		671.8	691.5
Accumulated Other Comprehensive Income (Loss)		2.9	2.6
TOTAL EQUITY		1,195.9	1,215.3
TOTAL LIABILITIES AND EQUITY		4,525.7	4,508.3
Southwestern Electric Power Co [Member]
Current Assets
Cash and Cash Equivalents		0.7	1.6
Advances to Affiliates		2.0	2.0
Accounts Receivable:
Customers		67.0	70.9
Affiliated Companies		18.0	30.2
Miscellaneous		13.2	25.8
Allowance for Uncollectible Accounts		(0.5)	(1.3)
Total Accounts Receivable		97.7	125.6
Fuel		120.5	123.6
Materials and Supplies		68.8	67.9
Risk Management Assets		1.7	6.4
Regulatory Asset for Under-Recovered Fuel Costs		16.5	14.1
Prepayments and Other Current Assets		40.2	39.2
TOTAL CURRENT ASSETS		348.1	380.4
Property, Plant and Equipment
Generation		4,622.6	4,624.9
Transmission		1,715.0	1,679.8
Distribution		2,108.1	2,095.8
Other Property, Plant and Equipment		704.4	684.1
Construction Work in Progress		266.9	233.2
Total Property, Plant and Equipment		9,417.0	9,317.8
Accumulated Depreciation and Amortization		2,724.7	2,685.8
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		6,692.3	6,632.0
Other Noncurrent Assets
Regulatory Assets		217.9	220.6
Deferred Charges and Other Noncurrent Assets		165.5	109.9
TOTAL OTHER NONCURRENT ASSETS		383.4	330.5
TOTAL ASSETS		7,423.8	7,342.9
Current Liabilities
Advances from Affiliates		148.6	118.7
Accounts Payable		118.5	160.4
Affiliated Companies		60.7	63.7
Short-term Debt:
Other Short-term Debt		22.6	22.0
Long-term Debt Due Within One Year		457.2	3.7
Risk Management Liabilities		0.1	0.2
Customer Deposits		62.9	62.1
Accrued Taxes		91.1	39.0
Accrued Interest		25.9	38.9
Obligations Under Capital Leases		11.3	11.2
Other Current Liabilities		60.4	78.7
TOTAL CURRENT LIABILITIES		1,059.3	598.6
Noncurrent Liabilities
Long-term Debt		2,046.5	2,438.2
Long-term Risk Management Liabilities		0.5	0.0
Deferred Income Taxes		924.2	917.7
Regulatory Liabilities and Deferred Investment Tax Credits		895.2	896.4
Asset Retirement Obligations		160.8	160.3
Employee Benefits and Pension Obligations		18.1	19.5
Obligations Under Capital Leases		56.9	57.8
Deferred Credits and Other Noncurrent Liabilities		36.4	19.9
TOTAL NONCURRENT LIABILITIES		4,138.6	4,509.8
TOTAL LIABILITIES		5,197.9	5,108.4
Rate Matters
Commitments and Contingencies
Equity
Common Stock		135.7	135.7
Paid-in Capital		676.6	676.6
Retained Earnings		1,418.0	1,426.6
Accumulated Other Comprehensive Income (Loss)		(4.8)	(4.0)
TOTAL COMMON SHAREHOLDER'S EQUITY		2,225.5	2,234.9
Noncontrolling Interests		0.4	(0.4)
TOTAL EQUITY		2,225.9	2,234.5
TOTAL LIABILITIES AND EQUITY		$ 7,423.8	$ 7,342.9

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