Condensed Consolidated Balance Sheets - USD ($) $ in Millions		Jun. 30, 2018	Dec. 31, 2017
Current Assets
Cash and Cash Equivalents		$ 211.2	$ 214.6
Restricted Cash		176.1	198.0
Other Temporary Investments		163.1	161.7
Accounts Receivable:
Customers		827.2	643.9
Accrued Unbilled Revenues		207.4	230.2
Pledged Accounts Receivable - AEP Credit		1,133.4	954.2
Miscellaneous		143.3	101.2
Allowance for Uncollectible Accounts		(40.6)	(38.5)
Total Accounts Receivable		2,270.7	1,891.0
Fuel		352.8	387.7
Materials and Supplies		562.8	565.5
Risk Management Assets		194.6	126.2
Regulatory Asset for Under-Recovered Fuel Costs		280.4	292.5
Margin Deposits		115.3	105.5
Prepayments and Other Current Assets		243.1	310.4
TOTAL CURRENT ASSETS		4,570.1	4,253.1
Property, Plant and Equipment
Generation		21,235.2	20,760.5
Transmission		19,818.7	18,972.5
Distribution		20,447.9	19,868.5
Other Property, Plant and Equipment		3,880.8	3,706.3
Construction Work in Progress		4,630.3	4,120.7
Total Property, Plant and Equipment		70,012.9	67,428.5
Accumulated Depreciation and Amortization		17,571.4	17,167.0
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		52,441.5	50,261.5
Other Noncurrent Assets
Regulatory Assets		3,375.6	3,587.6
Securitized Assets		1,082.1	1,211.2
Spent Nuclear Fuel and Decommissioning Trusts		2,554.9	2,527.6
Goodwill		52.5	52.5
Long-term Risk Management Assets		264.5	282.1
Deferred Charges and Other Noncurrent Assets		2,528.9	2,553.5
TOTAL OTHER NONCURRENT ASSETS		9,858.5	10,214.5
TOTAL ASSETS		66,870.1	64,729.1
Current Liabilities
Accounts Payable		1,635.4	2,065.3
Short-term Debt:
Securitized Debt for Receivables - AEP Credit	[1]	750.0	718.0
Other Short-term Debt		1,839.2	920.6
Total Short-term Debt		2,589.2	1,638.6
Long-term Debt Due Within One Year		2,281.4	1,753.7
Risk Management Liabilities		54.0	61.6
Customer Deposits		369.0	357.0
Accrued Taxes		943.9	1,115.5
Accrued Interest		235.2	234.5
Regulatory Liability for Over-Recovered Fuel Costs		11.4	11.9
Other Current Liabilities		938.8	1,033.2
TOTAL CURRENT LIABILITIES		9,058.3	8,271.3
Noncurrent Liabilities
Long-term Debt		19,750.6	19,419.6
Long-term Risk Management Liabilities		279.6	322.0
Deferred Income Taxes		7,085.3	6,813.9
Regulatory Liabilities and Deferred Investment Tax Credits		8,683.7	8,422.3
Asset Retirement Obligations		1,966.2	1,925.5
Employee Benefits and Pension Obligations		329.4	398.1
Deferred Credits and Other Noncurrent Liabilities		871.6	830.9
TOTAL NONCURRENT LIABILITIES		38,966.4	38,132.3
TOTAL LIABILITIES		48,024.7	46,403.6
Rate Matters
Commitments and Contingencies
Redeemable Noncontrolling Interest		70.4	0.0
Contingently Reedemable Performance Share Awards		23.6	11.9
Total Mezzanine Equity		94.0	11.9
Equity
Common Stock		3,335.4	3,329.4
Paid-in Capital		6,458.6	6,398.7
Retained Earnings		9,023.1	8,626.7
Accumulated Other Comprehensive Income (Loss)		(94.8)	(67.8)
TOTAL COMMON SHAREHOLDER'S EQUITY		18,722.3	18,287.0
Noncontrolling Interests		29.1	26.6
TOTAL EQUITY		18,751.4	18,313.6
TOTAL LIABILITIES AND EQUITY		66,870.1	64,729.1
AEP Texas Inc. [Member]
Current Assets
Cash and Cash Equivalents		0.1	2.0
Restricted Cash		131.9	155.2
Advances to Affiliates		27.1	111.9
Accounts Receivable:
Customers		138.9	105.3
Affiliated Companies		42.7	12.3
Accrued Unbilled Revenues		79.7	75.8
Miscellaneous		0.3	1.3
Allowance for Uncollectible Accounts		(0.5)	(0.7)
Total Accounts Receivable		261.1	194.0
Fuel		4.6	3.6
Materials and Supplies		50.5	52.0
Risk Management Assets		0.4	0.5
Accrued Tax Benefits		16.0	41.0
Prepayments and Other Current Assets		3.6	3.6
TOTAL CURRENT ASSETS		495.3	563.8
Property, Plant and Equipment
Generation		351.1	350.7
Transmission		3,263.3	3,053.6
Distribution		3,913.8	3,718.6
Other Property, Plant and Equipment		488.9	461.0
Construction Work in Progress		1,009.1	835.7
Total Property, Plant and Equipment		9,026.2	8,419.6
Accumulated Depreciation and Amortization		1,627.8	1,594.5
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		7,398.4	6,825.1
Other Noncurrent Assets
Regulatory Assets		399.3	378.7
Securitized Assets		786.6	891.2
Long-term Risk Management Assets		0.1	0.0
Deferred Charges and Other Noncurrent Assets		115.5	114.8
TOTAL OTHER NONCURRENT ASSETS		1,301.5	1,384.7
TOTAL ASSETS		9,195.2	8,773.6
Current Liabilities
Accounts Payable		220.1	379.4
Affiliated Companies		23.0	30.2
Short-term Debt:
Long-term Debt Due Within One Year		293.7	266.1
Accrued Taxes		89.7	77.2
Accrued Interest		41.5	42.2
Other Current Liabilities		81.6	76.4
TOTAL CURRENT LIABILITIES		749.6	871.5
Noncurrent Liabilities
Long-term Debt		3,697.6	3,383.2
Deferred Income Taxes		908.1	913.1
Regulatory Liabilities and Deferred Investment Tax Credits		1,336.1	1,320.5
Oklaunion Purchase Power Agreement		51.7	52.0
Deferred Credits and Other Noncurrent Liabilities		89.2	63.4
TOTAL NONCURRENT LIABILITIES		6,082.7	5,732.2
TOTAL LIABILITIES		6,832.3	6,603.7
Rate Matters
Commitments and Contingencies
Equity
Paid-in Capital		1,157.9	1,057.9
Retained Earnings		1,219.7	1,124.6
Accumulated Other Comprehensive Income (Loss)		(14.7)	(12.6)
TOTAL EQUITY		2,362.9	2,169.9
TOTAL LIABILITIES AND EQUITY		9,195.2	8,773.6
AEP Transmission Co [Member]
Current Assets
Cash and Cash Equivalents		0.0	0.0
Advances to Affiliates		53.6	146.3
Accounts Receivable:
Customers		15.3	19.1
Affiliated Companies		88.8	93.2
Miscellaneous		1.1	1.3
Total Accounts Receivable		105.2	113.6
Materials and Supplies		16.0	13.6
Accrued Tax Benefits		32.9	46.6
Prepayments and Other Current Assets		12.4	7.6
TOTAL CURRENT ASSETS		220.1	327.7
Property, Plant and Equipment
Transmission		5,700.0	5,336.1
Other Property, Plant and Equipment		140.5	131.4
Construction Work in Progress		1,585.9	1,312.7
Total Property, Plant and Equipment		7,426.4	6,780.2
Accumulated Depreciation and Amortization		210.5	170.4
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		7,215.9	6,609.8
Other Noncurrent Assets
Regulatory Assets		18.2	11.7
Deferred Tax Assets, Property, Plant and Equipment		73.1	117.8
Deferred Charges and Other Noncurrent Assets		7.4	1.1
TOTAL OTHER NONCURRENT ASSETS		98.7	130.6
TOTAL ASSETS		7,534.7	7,068.1
Current Liabilities
Advances from Affiliates		167.5	15.7
Accounts Payable		230.3	473.2
Affiliated Companies		66.8	52.9
Short-term Debt:
Long-term Debt Due Within One Year		50.0	50.0
Accrued Taxes		181.8	225.4
Accrued Interest		11.7	15.0
Other Current Liabilities		7.0	4.1
TOTAL CURRENT LIABILITIES		715.1	836.3
Noncurrent Liabilities
Long-term Debt		2,500.9	2,500.4
Deferred Income Taxes		659.0	601.7
Regulatory Liabilities and Deferred Investment Tax Credits		501.6	493.7
Deferred Credits and Other Noncurrent Liabilities		19.4	30.7
TOTAL NONCURRENT LIABILITIES		3,680.9	3,626.5
TOTAL LIABILITIES		4,396.0	4,462.8
Rate Matters
Commitments and Contingencies
Equity
Paid-in Captial		2,193.6	1,816.6
Retained Earnings		945.1	788.7
TOTAL MEMBER'S EQUITY		3,138.7	2,605.3
TOTAL LIABILITIES AND EQUITY		7,534.7	7,068.1
Appalachian Power Co [Member]
Current Assets
Cash and Cash Equivalents		2.8	2.9
Restricted Cash		17.7	16.3
Advances to Affiliates		23.4	23.5
Accounts Receivable:
Customers		177.9	123.1
Affiliated Companies		80.1	69.3
Accrued Unbilled Revenues		53.4	74.1
Miscellaneous		1.0	1.1
Allowance for Uncollectible Accounts		(3.9)	(3.7)
Total Accounts Receivable		308.5	263.9
Fuel		69.4	89.3
Materials and Supplies		99.2	99.5
Risk Management Assets		60.4	24.9
Regulatory Asset for Under-Recovered Fuel Costs		162.6	88.8
Margin Deposits		12.4	14.4
Prepayments and Other Current Assets		8.5	12.7
TOTAL CURRENT ASSETS		764.9	636.2
Property, Plant and Equipment
Generation		6,477.7	6,446.9
Transmission		3,082.9	3,019.9
Distribution		3,843.8	3,763.8
Other Property, Plant and Equipment		450.8	427.9
Construction Work in Progress		602.1	483.0
Total Property, Plant and Equipment		14,457.3	14,141.5
Accumulated Depreciation and Amortization		4,028.8	3,896.4
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		10,428.5	10,245.1
Other Noncurrent Assets
Regulatory Assets		527.4	573.9
Securitized Assets		270.4	282.3
Long-term Risk Management Assets		2.1	1.1
Deferred Charges and Other Noncurrent Assets		211.0	190.0
TOTAL OTHER NONCURRENT ASSETS		1,010.9	1,047.3
TOTAL ASSETS		12,204.3	11,928.6
Current Liabilities
Advances from Affiliates		172.7	186.0
Accounts Payable		227.7	264.9
Affiliated Companies		81.4	92.7
Short-term Debt:
Long-term Debt Due Within One Year		530.5	249.2
Risk Management Liabilities		1.4	1.3
Customer Deposits		88.0	86.1
Accrued Taxes		94.0	94.5
Accrued Interest		41.1	40.5
Other Current Liabilities		89.9	109.0
TOTAL CURRENT LIABILITIES		1,326.7	1,124.2
Noncurrent Liabilities
Long-term Debt		3,543.2	3,730.9
Long-term Risk Management Liabilities		0.5	0.2
Deferred Income Taxes		1,593.2	1,565.7
Regulatory Liabilities and Deferred Investment Tax Credits		1,522.3	1,454.9
Asset Retirement Obligations		105.5	100.2
Employee Benefits and Pension Obligations		66.2	73.3
Deferred Credits and Other Noncurrent Liabilities		120.9	74.7
TOTAL NONCURRENT LIABILITIES		6,951.8	6,999.9
TOTAL LIABILITIES		8,278.5	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		1,837.1	1,714.1
Accumulated Other Comprehensive Income (Loss)		(0.4)	1.3
TOTAL EQUITY		3,925.8	3,804.5
TOTAL LIABILITIES AND EQUITY		12,204.3	11,928.6
Indiana Michigan Power Co [Member]
Current Assets
Cash and Cash Equivalents		1.4	1.3
Advances to Affiliates		92.3	12.4
Accounts Receivable:
Customers		94.6	56.4
Affiliated Companies		63.1	50.0
Accrued Unbilled Revenues		4.3	7.3
Miscellaneous		1.7	2.0
Allowance for Uncollectible Accounts		0.0	(0.1)
Total Accounts Receivable		163.7	115.6
Fuel		33.1	31.4
Materials and Supplies		164.9	160.6
Risk Management Assets		14.4	7.6
Accrued Tax Benefits		59.2	58.4
Regulatory Asset for Under-Recovered Fuel Costs		4.3	15.0
Accrued Reimbursement of Spent Nuclear Fuel Costs		8.7	10.8
Prepayments and Other Current Assets		23.6	20.9
TOTAL CURRENT ASSETS		565.6	434.0
Property, Plant and Equipment
Generation		4,572.3	4,445.9
Transmission		1,529.8	1,504.0
Distribution		2,149.1	2,069.3
Other Property, Plant and Equipment		595.8	595.2
Construction Work in Progress		404.3	460.2
Total Property, Plant and Equipment		9,251.3	9,074.6
Accumulated Depreciation and Amortization		3,057.3	3,024.2
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		6,194.0	6,050.4
Other Noncurrent Assets
Regulatory Assets		562.6	579.4
Spent Nuclear Fuel and Decommissioning Trusts		2,554.9	2,527.6
Long-term Risk Management Assets		1.2	0.7
Deferred Charges and Other Noncurrent Assets		176.3	179.9
TOTAL OTHER NONCURRENT ASSETS		3,295.0	3,287.6
TOTAL ASSETS		10,054.6	9,772.0
Current Liabilities
Advances from Affiliates		0.0	211.6
Accounts Payable		162.0	154.5
Affiliated Companies		78.0	98.3
Short-term Debt:
Long-term Debt Due Within One Year		657.6	474.7
Risk Management Liabilities		5.4	3.5
Customer Deposits		37.6	37.7
Accrued Taxes		76.4	81.3
Accrued Interest		40.0	37.5
Obligations Under Capital Leases		5.7	5.8
Other Current Liabilities		86.1	106.4
TOTAL CURRENT LIABILITIES		1,148.8	1,211.3
Noncurrent Liabilities
Long-term Debt		2,439.2	2,270.4
Long-term Risk Management Liabilities		0.3	0.1
Deferred Income Taxes		1,004.2	953.8
Regulatory Liabilities and Deferred Investment Tax Credits		1,710.6	1,708.7
Asset Retirement Obligations		1,350.5	1,321.6
Deferred Credits and Other Noncurrent Liabilities		93.0	88.5
TOTAL NONCURRENT LIABILITIES		6,597.8	6,343.1
TOTAL LIABILITIES		7,746.6	7,554.4
Rate Matters
Commitments and Contingencies
Equity
Common Stock		56.6	56.6
Paid-in Capital		980.9	980.9
Retained Earnings		1,284.4	1,192.2
Accumulated Other Comprehensive Income (Loss)		(13.9)	(12.1)
TOTAL EQUITY		2,308.0	2,217.6
TOTAL LIABILITIES AND EQUITY		10,054.6	9,772.0
Ohio Power Co [Member]
Current Assets
Cash and Cash Equivalents		3.3	3.1
Restricted Cash		26.5	26.6
Accounts Receivable:
Customers		128.4	67.8
Affiliated Companies		75.8	70.2
Accrued Unbilled Revenues		21.7	29.7
Miscellaneous		0.7	1.9
Allowance for Uncollectible Accounts		(0.6)	(0.6)
Total Accounts Receivable		226.0	169.0
Materials and Supplies		40.0	41.9
Renewable Energy Credits		22.2	25.0
Risk Management Assets		0.4	0.6
Regulatory Asset for Under-Recovered Fuel Costs		56.3	115.9
Prepayments and Other Current Assets		28.3	15.8
TOTAL CURRENT ASSETS		403.0	397.9
Property, Plant and Equipment
Transmission		2,460.1	2,419.2
Distribution		4,740.9	4,626.4
Other Property, Plant and Equipment		532.6	495.9
Construction Work in Progress		445.2	410.1
Total Property, Plant and Equipment		8,178.8	7,951.6
Accumulated Depreciation and Amortization		2,218.6	2,184.8
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		5,960.2	5,766.8
Other Noncurrent Assets
Regulatory Assets		480.0	652.8
Securitized Assets		25.1	37.7
Long-term Risk Management Assets		0.1	0.0
Deferred Charges and Other Noncurrent Assets		324.2	406.5
TOTAL OTHER NONCURRENT ASSETS		829.4	1,097.0
TOTAL ASSETS		7,192.6	7,261.7
Current Liabilities
Advances from Affiliates		213.9	87.8
Accounts Payable		160.1	205.8
Affiliated Companies		95.3	118.2
Short-term Debt:
Long-term Debt Due Within One Year		47.5	397.0
Risk Management Liabilities		4.8	6.4
Customer Deposits		77.6	69.2
Accrued Taxes		341.5	512.5
Other Current Liabilities		187.0	196.9
TOTAL CURRENT LIABILITIES		1,127.7	1,593.8
Noncurrent Liabilities
Long-term Debt		1,692.5	1,322.3
Long-term Risk Management Liabilities		82.0	126.0
Deferred Income Taxes		751.4	762.9
Regulatory Liabilities and Deferred Investment Tax Credits		1,222.4	1,100.2
Deferred Credits and Other Noncurrent Liabilities		83.1	46.2
TOTAL NONCURRENT LIABILITIES		3,831.4	3,357.6
TOTAL LIABILITIES		4,959.1	4,951.4
Rate Matters
Commitments and Contingencies
Equity
Common Stock		321.2	321.2
Paid-in Capital		838.8	838.8
Retained Earnings		1,071.8	1,148.4
Accumulated Other Comprehensive Income (Loss)		1.7	1.9
TOTAL EQUITY		2,233.5	2,310.3
TOTAL LIABILITIES AND EQUITY		7,192.6	7,261.7
Public Service Co Of Oklahoma [Member]
Current Assets
Cash and Cash Equivalents		1.6	1.6
Accounts Receivable:
Customers		29.7	32.5
Affiliated Companies		42.9	32.9
Miscellaneous		3.2	4.1
Allowance for Uncollectible Accounts		0.0	(0.1)
Total Accounts Receivable		75.8	69.4
Fuel		11.8	12.5
Materials and Supplies		43.5	42.0
Risk Management Assets		24.5	6.4
Accrued Tax Benefits		20.4	28.1
Regulatory Asset for Under-Recovered Fuel Costs		7.4	36.7
Prepayments and Other Current Assets		7.7	8.6
TOTAL CURRENT ASSETS		192.7	205.3
Property, Plant and Equipment
Generation		1,574.7	1,577.2
Transmission		871.4	858.8
Distribution		2,503.7	2,445.1
Other Property, Plant and Equipment		301.4	287.4
Construction Work in Progress		103.1	111.3
Total Property, Plant and Equipment		5,354.3	5,279.8
Accumulated Depreciation and Amortization		1,439.3	1,393.6
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		3,915.0	3,886.2
Other Noncurrent Assets
Regulatory Assets		362.9	368.1
Employee Benefits and Pension Assets		40.8	40.0
Deferred Charges and Other Noncurrent Assets		23.8	8.7
TOTAL OTHER NONCURRENT ASSETS		427.5	416.8
TOTAL ASSETS		4,535.2	4,508.3
Current Liabilities
Advances from Affiliates		118.4	149.6
Accounts Payable		125.7	102.4
Affiliated Companies		48.0	48.0
Short-term Debt:
Long-term Debt Due Within One Year		0.5	0.5
Customer Deposits		55.3	54.1
Accrued Taxes		40.0	22.6
Accrued Interest		13.3	14.1
Other Current Liabilities		45.9	44.7
TOTAL CURRENT LIABILITIES		447.1	436.0
Noncurrent Liabilities
Long-term Debt		1,286.3	1,286.0
Deferred Income Taxes		635.0	642.0
Regulatory Liabilities and Deferred Investment Tax Credits		851.8	853.5
Asset Retirement Obligations		54.1	53.0
Deferred Credits and Other Noncurrent Liabilities		41.2	22.5
TOTAL NONCURRENT LIABILITIES		2,868.4	2,857.0
TOTAL LIABILITIES		3,315.5	3,293.0
Rate Matters
Commitments and Contingencies
Equity
Common Stock		157.2	157.2
Paid-in Capital		364.0	364.0
Retained Earnings		695.9	691.5
Accumulated Other Comprehensive Income (Loss)		2.6	2.6
TOTAL EQUITY		1,219.7	1,215.3
TOTAL LIABILITIES AND EQUITY		4,535.2	4,508.3
Southwestern Electric Power Co [Member]
Current Assets
Cash and Cash Equivalents		2.1	1.6
Advances to Affiliates		2.0	2.0
Accounts Receivable:
Customers		45.1	70.9
Affiliated Companies		38.3	30.2
Miscellaneous		21.0	25.8
Allowance for Uncollectible Accounts		(0.5)	(1.3)
Total Accounts Receivable		103.9	125.6
Fuel		121.2	123.6
Materials and Supplies		69.1	67.9
Risk Management Assets		7.4	6.4
Regulatory Asset for Under-Recovered Fuel Costs		16.0	14.1
Prepayments and Other Current Assets		42.0	39.2
TOTAL CURRENT ASSETS		363.7	380.4
Property, Plant and Equipment
Generation		4,636.3	4,624.9
Transmission		1,795.2	1,679.8
Distribution		2,124.4	2,095.8
Other Property, Plant and Equipment		733.9	684.1
Construction Work in Progress		228.6	233.2
Total Property, Plant and Equipment		9,518.4	9,317.8
Accumulated Depreciation and Amortization		2,759.3	2,685.8
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		6,759.1	6,632.0
Other Noncurrent Assets
Regulatory Assets		221.4	220.6
Deferred Charges and Other Noncurrent Assets		149.3	109.9
TOTAL OTHER NONCURRENT ASSETS		370.7	330.5
TOTAL ASSETS		7,493.5	7,342.9
Current Liabilities
Advances from Affiliates		119.9	118.7
Accounts Payable		120.4	160.4
Affiliated Companies		53.2	63.7
Short-term Debt:
Other Short-term Debt		25.2	22.0
Long-term Debt Due Within One Year		457.2	3.7
Risk Management Liabilities		0.0	0.2
Customer Deposits		64.0	62.1
Accrued Taxes		80.4	39.0
Accrued Interest		39.0	38.9
Obligations Under Capital Leases		11.1	11.2
Other Current Liabilities		93.0	78.7
TOTAL CURRENT LIABILITIES		1,063.4	598.6
Noncurrent Liabilities
Long-term Debt		2,046.5	2,438.2
Long-term Risk Management Liabilities		2.3	0.0
Deferred Income Taxes		926.6	917.7
Regulatory Liabilities and Deferred Investment Tax Credits		898.0	896.4
Asset Retirement Obligations		180.0	160.3
Employee Benefits and Pension Obligations		18.9	19.5
Obligations Under Capital Leases		55.0	57.8
Deferred Credits and Other Noncurrent Liabilities		59.1	19.9
TOTAL NONCURRENT LIABILITIES		4,186.4	4,509.8
TOTAL LIABILITIES		5,249.8	5,108.4
Rate Matters
Commitments and Contingencies
Equity
Common Stock		135.7	135.7
Paid-in Capital		676.6	676.6
Retained Earnings		1,435.6	1,426.6
Accumulated Other Comprehensive Income (Loss)		(4.7)	(4.0)
TOTAL COMMON SHAREHOLDER'S EQUITY		2,243.2	2,234.9
Noncontrolling Interests		0.5	(0.4)
TOTAL EQUITY		2,243.7	2,234.5
TOTAL LIABILITIES AND EQUITY		$ 7,493.5	$ 7,342.9

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