Leases (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019		Jun. 30, 2019		Jun. 30, 2018	Mar. 31, 2019	Dec. 31, 2018
Lease Rental Costs
Operating Lease, Cost	$ 71.3		$ 135.9
Finance Lease Right-of-Use Asset Amortization	14.3		28.5
Interest Expense on Finance Leases	4.0		8.1
Total Lease Rental Costs	$ 89.6		$ 172.5
Supplemental Information Related to Leases
Weighted-Average Remaining Lease Term, Operating Leases	5 years 5 months 12 days		5 years 5 months 12 days
Weighted Average Remaining Lease Term, Finance Leases	5 years 10 months 17 days		5 years 10 months 17 days
Weighted Average Discount Rate, Operating Leases	3.63%		3.63%
Weighted Average Discount Rate, Finance Leases	6.16%		6.16%
Operating Cash Flows from Operating Leases			$ 132.3
Operating Cash Flows from Finance Leases			8.1
Financing Cash Flows from Finance Leases			29.6		$ 33.5
Non-cash Acquisitions Under Operating Leases			84.2
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Generation	$ 22,098.3		22,098.3				$ 21,699.9
Other Property, Plant and Equipment	4,452.2		4,452.2				4,265.0
Total Property, Plant and Equipment	75,642.0		75,642.0				73,085.2
Accumulated Amortization	18,439.1		18,439.1				17,986.1
Net Property, Plant and Equipment Under Finance Leases	302.4		302.4
Obligations Under Finance Leases Noncurrent	763.1		763.1				782.6
Finance Lease Liability Due Within One Year	1,038.5		1,038.5				1,190.5
Total Obligations Under Finance Leases	306.7		306.7
Operating Lease Asset and Related Obligations
Operating Lease Assets	1,016.5		1,016.5				0.0
Operating Lease Assets, Noncurrent	11,285.8		11,285.8				9,589.8
Operating Lease Noncurrent Liability	797.2		797.2				0.0
Operating Lease Liability Due Within One Year	229.2		229.2				0.0
Total Obligations Under Operating Leases	1,026.4		1,026.4
Finance Lease Liabilities Rolling Future Minimum Lease Payments
Finance Leases, Year 1	75.1		75.1
Finance Leases, Year 2	65.0		65.0
Finance Leases, Year 3	56.2		56.2
Finance Leases, Year 4	47.4		47.4
Finance Leases, Year 5	44.2		44.2
Finance Leases, Later Years	84.0		84.0
Finance Leases, Total Future Minimum Lease Payments	371.9		371.9
Imputed Interest on Finance Leases	65.2		65.2
Total Obligations Under Finance Leases	306.7		306.7
Operating Lease Liabilities Rolling Future Minimum Lease Payments
Operating Leases, Year 1	265.4		265.4
Operating Leases, Year 2	253.1		253.1
Operating Leases, Year 3	237.7		237.7
Operating Leases, Year 4	154.4		154.4
Operating Leases, Year 5	63.0		63.0
Operating Leases, Later Years	182.6		182.6
Operating Leases, Total Future Minimum Lease Payments	1,156.2		1,156.2
Imputed Interest on Operating Leases	129.8		129.8
Estimated Present Value of Future Minimum Lease Payments on Operating Leases	1,026.4		1,026.4
Finance Lease Future Minimum Lease Payments
Capital Leases, 2019							70.8
Capital Leases, 2020							60.2
Capital Leases, 2021							51.7
Capital Leases, 2022							43.8
Capital Leases, 2023							35.5
Capital Leases, Later Years							90.2
Capital Leases, Total Future Minimum Payments Due							352.2
Estimated Interest Element on Capital Leases							63.2
Estimated Present Value of Future Minimum Lease Payments on Capital Leases							289.0
Operating Lease Future Minimum Lease Payments
Noncancelable Operating Leases, 2019							259.6
Noncancelable Operating Leases, 2020							250.1
Noncancelable Operating Leases, 2021							232.7
Noncancelable Operating Leases, 2022							222.5
Noncancelable Operating Leases, 2023							58.3
Noncancelable Operating Leases, Later Years							165.2
Noncancelable Operating Leases Total Future Minimum Lease Payments							1,188.4
Maximum Potential Loss
Max Potential Loss on Master Lease Agreements	46.1		46.1
Rockport Lease [Member]
Future Minimum Rentals, Sale Leaseback Transactions
2019	74.2		74.2
2020	147.8		147.8
2021	147.8		147.8
2022	147.2		147.2
Total Future Minimum Lease Payments	517.0		517.0
Leases (Textuals)
Sale and Leaseback Transaction, Gain (Loss), Net			$ 37.0
Lease Term			33 years
Boat and Barge Leases [Member]
Leases (Textuals)
Maximum Potential Lease Payments, AEPRO Barge and Boat Leases						$ 58.0
Guarantor Obligations, Current Carrying Value						5.0
Guarantee Obligations Current Carrying Value Other Liabilities Current						1.0
Guarantee Obligations Current Carrying Value Other Liabilities Noncurrent						$ 4.0
Finance Lease Assets [Member]
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Generation	131.2		$ 131.2
Other Property, Plant and Equipment	325.5		325.5
Total Property, Plant and Equipment	456.7		456.7
Accumulated Amortization	154.3		154.3
Finance Lease Liabilities [Member]
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Obligations Under Finance Leases Noncurrent	247.1		247.1
Finance Lease Liability Due Within One Year	59.6		59.6
AEP Texas Inc. [Member]
Lease Rental Costs
Operating Lease, Cost	4.4		8.2
Finance Lease Right-of-Use Asset Amortization	1.2		2.3
Interest Expense on Finance Leases	0.4		0.7
Total Lease Rental Costs	$ 6.0		$ 11.2
Supplemental Information Related to Leases
Weighted-Average Remaining Lease Term, Operating Leases	7 years 2 months 8 days		7 years 2 months 8 days
Weighted Average Remaining Lease Term, Finance Leases	7 years		7 years
Weighted Average Discount Rate, Operating Leases	3.82%		3.82%
Weighted Average Discount Rate, Finance Leases	4.79%		4.79%
Operating Cash Flows from Operating Leases			$ 7.5
Operating Cash Flows from Finance Leases			0.7
Financing Cash Flows from Finance Leases			2.5		2.3
Non-cash Acquisitions Under Operating Leases			10.7
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Generation	$ 351.8		351.8				352.1
Other Property, Plant and Equipment	766.7		766.7				727.9
Total Property, Plant and Equipment	10,093.3		10,093.3				9,643.0
Accumulated Amortization	1,712.6		1,712.6				1,651.2
Net Property, Plant and Equipment Under Finance Leases	30.3		30.3
Obligations Under Finance Leases Noncurrent	110.1		110.1				104.0
Finance Lease Liability Due Within One Year	85.1		85.1				98.3
Total Obligations Under Finance Leases	30.3		30.3
Operating Lease Asset and Related Obligations
Operating Lease Assets, Noncurrent	1,201.9		1,201.9				1,135.4
Operating Lease Noncurrent Liability	69.9		69.9				0.0
Operating Lease Liability Due Within One Year	11.6		11.6				0.0
Total Obligations Under Operating Leases	81.5		81.5
Finance Lease Liabilities Rolling Future Minimum Lease Payments
Finance Leases, Year 1	6.3		6.3
Finance Leases, Year 2	5.9		5.9
Finance Leases, Year 3	5.2		5.2
Finance Leases, Year 4	4.7		4.7
Finance Leases, Year 5	4.0		4.0
Finance Leases, Later Years	10.2		10.2
Finance Leases, Total Future Minimum Lease Payments	36.3		36.3
Imputed Interest on Finance Leases	6.0		6.0
Total Obligations Under Finance Leases	30.3		30.3
Operating Lease Liabilities Rolling Future Minimum Lease Payments
Operating Leases, Year 1	15.3		15.3
Operating Leases, Year 2	14.7		14.7
Operating Leases, Year 3	13.6		13.6
Operating Leases, Year 4	12.6		12.6
Operating Leases, Year 5	11.1		11.1
Operating Leases, Later Years	28.4		28.4
Operating Leases, Total Future Minimum Lease Payments	95.7		95.7
Imputed Interest on Operating Leases	14.2		14.2
Estimated Present Value of Future Minimum Lease Payments on Operating Leases	81.5		81.5
Finance Lease Future Minimum Lease Payments
Capital Leases, 2019							5.8
Capital Leases, 2020							5.3
Capital Leases, 2021							4.7
Capital Leases, 2022							4.2
Capital Leases, 2023							3.7
Capital Leases, Later Years							10.1
Capital Leases, Total Future Minimum Payments Due							33.8
Estimated Interest Element on Capital Leases							5.3
Estimated Present Value of Future Minimum Lease Payments on Capital Leases							28.5
Operating Lease Future Minimum Lease Payments
Noncancelable Operating Leases, 2019							15.1
Noncancelable Operating Leases, 2020							14.1
Noncancelable Operating Leases, 2021							13.2
Noncancelable Operating Leases, 2022							12.2
Noncancelable Operating Leases, 2023							10.8
Noncancelable Operating Leases, Later Years							28.4
Noncancelable Operating Leases Total Future Minimum Lease Payments							93.8
Maximum Potential Loss
Max Potential Loss on Master Lease Agreements	10.9		10.9
AEP Texas Inc. [Member] | Finance Lease Assets [Member]
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Generation	0.0		0.0
Other Property, Plant and Equipment	40.9		40.9
Total Property, Plant and Equipment	40.9		40.9
Accumulated Amortization	10.6		10.6
AEP Texas Inc. [Member] | Finance Lease Liabilities [Member]
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Obligations Under Finance Leases Noncurrent	25.3		25.3
Finance Lease Liability Due Within One Year	5.0		5.0
AEP Texas Inc. [Member] | Operating Lease Assets [Member]
Operating Lease Asset and Related Obligations
Operating Lease Assets, Noncurrent	80.9		80.9
AEP Transmission Co [Member]
Lease Rental Costs
Operating Lease, Cost	0.5		1.1
Finance Lease Right-of-Use Asset Amortization	0.0		0.0
Interest Expense on Finance Leases	0.0		0.0
Total Lease Rental Costs	$ 0.5		$ 1.1
Supplemental Information Related to Leases
Weighted-Average Remaining Lease Term, Operating Leases	2 years 6 months 10 days		2 years 6 months 10 days
Weighted Average Remaining Lease Term, Finance Leases	25 days		25 days
Weighted Average Discount Rate, Operating Leases	3.15%		3.15%
Weighted Average Discount Rate, Finance Leases	9.33%		9.33%
Operating Cash Flows from Operating Leases			$ 1.1
Operating Cash Flows from Finance Leases			0.0
Financing Cash Flows from Finance Leases			0.0
Non-cash Acquisitions Under Operating Leases			0.0
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Other Property, Plant and Equipment	$ 222.2		222.2				174.0
Total Property, Plant and Equipment	8,907.5	[1]	8,907.5	[1]			8,268.1
Accumulated Amortization	336.6	[1]	336.6	[1]			271.9
Net Property, Plant and Equipment Under Finance Leases	0.1		0.1
Obligations Under Finance Leases Noncurrent	6.5		6.5				18.4
Finance Lease Liability Due Within One Year	30.5		30.5				3.8
Total Obligations Under Finance Leases	0.1		0.1
Operating Lease Asset and Related Obligations
Operating Lease Assets, Noncurrent	113.8		113.8				172.4
Operating Lease Noncurrent Liability	2.8		2.8				0.0
Operating Lease Liability Due Within One Year	2.6		2.6				0.0
Total Obligations Under Operating Leases	5.4		5.4
Finance Lease Liabilities Rolling Future Minimum Lease Payments
Finance Leases, Year 1	0.1		0.1
Finance Leases, Year 2	0.0		0.0
Finance Leases, Year 3	0.0		0.0
Finance Leases, Year 4	0.0		0.0
Finance Leases, Year 5	0.0		0.0
Finance Leases, Later Years	0.0		0.0
Finance Leases, Total Future Minimum Lease Payments	0.1		0.1
Imputed Interest on Finance Leases	0.0		0.0
Total Obligations Under Finance Leases	0.1		0.1
Operating Lease Liabilities Rolling Future Minimum Lease Payments
Operating Leases, Year 1	2.8		2.8
Operating Leases, Year 2	1.7		1.7
Operating Leases, Year 3	0.7		0.7
Operating Leases, Year 4	0.5		0.5
Operating Leases, Year 5	0.0		0.0
Operating Leases, Later Years	0.0		0.0
Operating Leases, Total Future Minimum Lease Payments	5.7		5.7
Imputed Interest on Operating Leases	0.3		0.3
Estimated Present Value of Future Minimum Lease Payments on Operating Leases	5.4		5.4
Finance Lease Future Minimum Lease Payments
Capital Leases, 2019							0.1
Capital Leases, 2020							0.0
Capital Leases, 2021							0.0
Capital Leases, 2022							0.0
Capital Leases, 2023							0.0
Capital Leases, Later Years							0.0
Capital Leases, Total Future Minimum Payments Due							0.1
Estimated Interest Element on Capital Leases							0.0
Estimated Present Value of Future Minimum Lease Payments on Capital Leases							0.1
Operating Lease Future Minimum Lease Payments
Noncancelable Operating Leases, 2019							2.3
Noncancelable Operating Leases, 2020							1.8
Noncancelable Operating Leases, 2021							1.0
Noncancelable Operating Leases, 2022							0.5
Noncancelable Operating Leases, 2023							0.1
Noncancelable Operating Leases, Later Years							0.0
Noncancelable Operating Leases Total Future Minimum Lease Payments							5.7
AEP Transmission Co [Member] | Finance Lease Assets [Member]
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Generation	0.0		0.0
Other Property, Plant and Equipment	0.2		0.2
Total Property, Plant and Equipment	0.2		0.2
Accumulated Amortization	0.1		0.1
AEP Transmission Co [Member] | Finance Lease Liabilities [Member]
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Obligations Under Finance Leases Noncurrent	0.0		0.0
Finance Lease Liability Due Within One Year	0.1		0.1
AEP Transmission Co [Member] | Operating Lease Assets [Member]
Operating Lease Asset and Related Obligations
Operating Lease Assets, Noncurrent	5.4		5.4
Appalachian Power Co [Member]
Lease Rental Costs
Operating Lease, Cost	5.0		9.6
Finance Lease Right-of-Use Asset Amortization	1.5		3.0
Interest Expense on Finance Leases	0.7		1.4
Total Lease Rental Costs	$ 7.2		$ 14.0
Supplemental Information Related to Leases
Weighted-Average Remaining Lease Term, Operating Leases	6 years 4 months 2 days		6 years 4 months 2 days
Weighted Average Remaining Lease Term, Finance Leases	6 years 3 months 3 days		6 years 3 months 3 days
Weighted Average Discount Rate, Operating Leases	3.68%		3.68%
Weighted Average Discount Rate, Finance Leases	8.55%		8.55%
Operating Cash Flows from Operating Leases			$ 9.5
Operating Cash Flows from Finance Leases			1.4
Financing Cash Flows from Finance Leases			3.1		3.4
Non-cash Acquisitions Under Operating Leases			7.0
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Generation	$ 6,547.5		6,547.5				6,509.6
Other Property, Plant and Equipment	517.0		517.0				485.8
Total Property, Plant and Equipment	15,088.2		15,088.2				14,792.7
Accumulated Amortization	4,230.8		4,230.8				4,124.4
Net Property, Plant and Equipment Under Finance Leases	42.3		42.3
Obligations Under Finance Leases Noncurrent	59.2		59.2				58.6
Finance Lease Liability Due Within One Year	108.7		108.7				150.3
Total Obligations Under Finance Leases	42.3		42.3
Operating Lease Asset and Related Obligations
Operating Lease Assets	78.3		78.3				0.0
Operating Lease Assets, Noncurrent	971.5		971.5				923.5
Operating Lease Noncurrent Liability	63.8		63.8				0.0
Operating Lease Liability Due Within One Year	14.9		14.9				0.0
Total Obligations Under Operating Leases	78.7		78.7
Finance Lease Liabilities Rolling Future Minimum Lease Payments
Finance Leases, Year 1	9.5		9.5
Finance Leases, Year 2	8.7		8.7
Finance Leases, Year 3	7.9		7.9
Finance Leases, Year 4	7.4		7.4
Finance Leases, Year 5	6.9		6.9
Finance Leases, Later Years	13.0		13.0
Finance Leases, Total Future Minimum Lease Payments	53.4		53.4
Imputed Interest on Finance Leases	11.1		11.1
Total Obligations Under Finance Leases	42.3		42.3
Operating Lease Liabilities Rolling Future Minimum Lease Payments
Operating Leases, Year 1	18.0		18.0
Operating Leases, Year 2	16.1		16.1
Operating Leases, Year 3	14.3		14.3
Operating Leases, Year 4	12.6		12.6
Operating Leases, Year 5	9.6		9.6
Operating Leases, Later Years	19.8		19.8
Operating Leases, Total Future Minimum Lease Payments	90.4		90.4
Imputed Interest on Operating Leases	11.7		11.7
Estimated Present Value of Future Minimum Lease Payments on Operating Leases	78.7		78.7
Finance Lease Future Minimum Lease Payments
Capital Leases, 2019							9.0
Capital Leases, 2020							8.0
Capital Leases, 2021							7.3
Capital Leases, 2022							6.8
Capital Leases, 2023							6.3
Capital Leases, Later Years							13.3
Capital Leases, Total Future Minimum Payments Due							50.7
Estimated Interest Element on Capital Leases							10.9
Estimated Present Value of Future Minimum Lease Payments on Capital Leases							39.8
Operating Lease Future Minimum Lease Payments
Noncancelable Operating Leases, 2019							17.6
Noncancelable Operating Leases, 2020							16.5
Noncancelable Operating Leases, 2021							13.9
Noncancelable Operating Leases, 2022							12.8
Noncancelable Operating Leases, 2023							9.9
Noncancelable Operating Leases, Later Years							20.5
Noncancelable Operating Leases Total Future Minimum Lease Payments							91.2
Maximum Potential Loss
Max Potential Loss on Master Lease Agreements	6.1		6.1
Appalachian Power Co [Member] | Finance Lease Assets [Member]
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Generation	38.6		38.6
Other Property, Plant and Equipment	20.4		20.4
Total Property, Plant and Equipment	59.0		59.0
Accumulated Amortization	16.7		16.7
Appalachian Power Co [Member] | Finance Lease Liabilities [Member]
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Obligations Under Finance Leases Noncurrent	35.7		35.7
Finance Lease Liability Due Within One Year	6.6		6.6
Indiana Michigan Power Co [Member]
Lease Rental Costs
Operating Lease, Cost	23.3		46.3
Finance Lease Right-of-Use Asset Amortization	1.3		2.6
Interest Expense on Finance Leases	0.7		1.5
Total Lease Rental Costs	$ 25.3		$ 50.4
Supplemental Information Related to Leases
Weighted-Average Remaining Lease Term, Operating Leases	4 years 3 months		4 years 3 months
Weighted Average Remaining Lease Term, Finance Leases	6 years 9 months 14 days		6 years 9 months 14 days
Weighted Average Discount Rate, Operating Leases	3.46%		3.46%
Weighted Average Discount Rate, Finance Leases	8.97%		8.97%
Operating Cash Flows from Operating Leases			$ 47.0
Operating Cash Flows from Finance Leases			1.5
Financing Cash Flows from Finance Leases			2.7		5.2
Non-cash Acquisitions Under Operating Leases			11.3
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Generation	$ 4,987.2		4,987.2				4,887.2
Other Property, Plant and Equipment	617.0		617.0				583.8
Total Property, Plant and Equipment	10,011.7		10,011.7				9,762.8
Accumulated Amortization	3,227.6		3,227.6				3,151.6
Net Property, Plant and Equipment Under Finance Leases	40.4		40.4
Obligations Under Finance Leases Noncurrent	63.4		63.4				87.8
Finance Lease Liability Due Within One Year	71.4		71.4				103.0
Total Obligations Under Finance Leases	40.4		40.4
Operating Lease Asset and Related Obligations
Operating Lease Assets	312.6		312.6				0.0
Operating Lease Assets, Noncurrent	3,738.0		3,738.0				3,181.0
Operating Lease Noncurrent Liability	234.7		234.7				0.0
Operating Lease Liability Due Within One Year	82.2		82.2				0.0
Total Obligations Under Operating Leases	316.9		316.9
Finance Lease Liabilities Rolling Future Minimum Lease Payments
Finance Leases, Year 1	8.5		8.5
Finance Leases, Year 2	7.8		7.8
Finance Leases, Year 3	7.1		7.1
Finance Leases, Year 4	6.6		6.6
Finance Leases, Year 5	6.3		6.3
Finance Leases, Later Years	21.6		21.6
Finance Leases, Total Future Minimum Lease Payments	57.9		57.9
Imputed Interest on Finance Leases	17.5		17.5
Total Obligations Under Finance Leases	40.4		40.4
Operating Lease Liabilities Rolling Future Minimum Lease Payments
Operating Leases, Year 1	92.5		92.5
Operating Leases, Year 2	89.4		89.4
Operating Leases, Year 3	86.0		86.0
Operating Leases, Year 4	48.3		48.3
Operating Leases, Year 5	7.7		7.7
Operating Leases, Later Years	21.9		21.9
Operating Leases, Total Future Minimum Lease Payments	345.8		345.8
Imputed Interest on Operating Leases	28.9		28.9
Estimated Present Value of Future Minimum Lease Payments on Operating Leases	316.9		316.9
Finance Lease Future Minimum Lease Payments
Capital Leases, 2019							8.2
Capital Leases, 2020							7.2
Capital Leases, 2021							6.6
Capital Leases, 2022							6.1
Capital Leases, 2023							5.7
Capital Leases, Later Years							21.7
Capital Leases, Total Future Minimum Payments Due							55.5
Estimated Interest Element on Capital Leases							16.8
Estimated Present Value of Future Minimum Lease Payments on Capital Leases							38.7
Operating Lease Future Minimum Lease Payments
Noncancelable Operating Leases, 2019							92.6
Noncancelable Operating Leases, 2020							89.3
Noncancelable Operating Leases, 2021							84.8
Noncancelable Operating Leases, 2022							83.8
Noncancelable Operating Leases, 2023							6.5
Noncancelable Operating Leases, Later Years							19.5
Noncancelable Operating Leases Total Future Minimum Lease Payments							376.5
Maximum Potential Loss
Max Potential Loss on Master Lease Agreements	4.0		4.0
Indiana Michigan Power Co [Member] | Rockport Lease [Member]
Future Minimum Rentals, Sale Leaseback Transactions
2019	37.1		37.1
2020	73.9		73.9
2021	73.9		73.9
2022	73.6		73.6
Total Future Minimum Lease Payments	258.5		258.5
Leases (Textuals)
Sale and Leaseback Transaction, Gain (Loss), Net			$ 15.0
Lease Term			33 years
Indiana Michigan Power Co [Member] | Finance Lease Assets [Member]
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Generation	27.0		$ 27.0
Other Property, Plant and Equipment	35.4		35.4
Total Property, Plant and Equipment	62.4		62.4
Accumulated Amortization	22.0		22.0
Indiana Michigan Power Co [Member] | Finance Lease Liabilities [Member]
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Obligations Under Finance Leases Noncurrent	34.9		34.9
Finance Lease Liability Due Within One Year	5.5		5.5
Ohio Power Co [Member]
Lease Rental Costs
Operating Lease, Cost	5.3		8.9
Finance Lease Right-of-Use Asset Amortization	0.8		1.5
Interest Expense on Finance Leases	0.1		0.3
Total Lease Rental Costs	$ 6.2		$ 10.7
Supplemental Information Related to Leases
Weighted-Average Remaining Lease Term, Operating Leases	8 years 2 months 8 days		8 years 2 months 8 days
Weighted Average Remaining Lease Term, Finance Leases	6 years 5 months 1 day		6 years 5 months 1 day
Weighted Average Discount Rate, Operating Leases	3.83%		3.83%
Weighted Average Discount Rate, Finance Leases	4.80%		4.80%
Operating Cash Flows from Operating Leases			$ 8.5
Operating Cash Flows from Finance Leases			0.3
Financing Cash Flows from Finance Leases			1.8		1.9
Non-cash Acquisitions Under Operating Leases			30.0
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Other Property, Plant and Equipment	$ 643.3		643.3				574.8
Total Property, Plant and Equipment	8,781.1		8,781.1				8,493.5
Accumulated Amortization	2,238.8		2,238.8				2,218.6
Net Property, Plant and Equipment Under Finance Leases	16.5		16.5
Obligations Under Finance Leases Noncurrent	47.5		47.5				43.8
Finance Lease Liability Due Within One Year	181.5		181.5				214.2
Total Obligations Under Finance Leases	16.5		16.5
Operating Lease Asset and Related Obligations
Operating Lease Assets, Noncurrent	775.0		775.0				841.4
Operating Lease Noncurrent Liability	75.4		75.4				0.0
Operating Lease Liability Due Within One Year	13.2		13.2				0.0
Total Obligations Under Operating Leases	88.6		88.6
Finance Lease Liabilities Rolling Future Minimum Lease Payments
Finance Leases, Year 1	4.0		4.0
Finance Leases, Year 2	3.6		3.6
Finance Leases, Year 3	3.0		3.0
Finance Leases, Year 4	2.3		2.3
Finance Leases, Year 5	1.9		1.9
Finance Leases, Later Years	4.8		4.8
Finance Leases, Total Future Minimum Lease Payments	19.6		19.6
Imputed Interest on Finance Leases	3.1		3.1
Total Obligations Under Finance Leases	16.5		16.5
Operating Lease Liabilities Rolling Future Minimum Lease Payments
Operating Leases, Year 1	16.4		16.4
Operating Leases, Year 2	14.3		14.3
Operating Leases, Year 3	12.9		12.9
Operating Leases, Year 4	12.1		12.1
Operating Leases, Year 5	10.5		10.5
Operating Leases, Later Years	38.9		38.9
Operating Leases, Total Future Minimum Lease Payments	105.1		105.1
Imputed Interest on Operating Leases	16.5		16.5
Estimated Present Value of Future Minimum Lease Payments on Operating Leases	88.6		88.6
Finance Lease Future Minimum Lease Payments
Capital Leases, 2019							3.3
Capital Leases, 2020							2.7
Capital Leases, 2021							2.3
Capital Leases, 2022							1.7
Capital Leases, 2023							1.2
Capital Leases, Later Years							2.8
Capital Leases, Total Future Minimum Payments Due							14.0
Estimated Interest Element on Capital Leases							1.9
Estimated Present Value of Future Minimum Lease Payments on Capital Leases							12.1
Operating Lease Future Minimum Lease Payments
Noncancelable Operating Leases, 2019							14.5
Noncancelable Operating Leases, 2020							13.2
Noncancelable Operating Leases, 2021							10.9
Noncancelable Operating Leases, 2022							10.0
Noncancelable Operating Leases, 2023							8.8
Noncancelable Operating Leases, Later Years							31.7
Noncancelable Operating Leases Total Future Minimum Lease Payments							89.1
Maximum Potential Loss
Max Potential Loss on Master Lease Agreements	7.7		7.7
Ohio Power Co [Member] | Finance Lease Assets [Member]
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Generation	0.0		0.0
Other Property, Plant and Equipment	23.0		23.0
Total Property, Plant and Equipment	23.0		23.0
Accumulated Amortization	6.5		6.5
Ohio Power Co [Member] | Finance Lease Liabilities [Member]
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Obligations Under Finance Leases Noncurrent	13.2		13.2
Finance Lease Liability Due Within One Year	3.3		3.3
Ohio Power Co [Member] | Operating Lease Assets [Member]
Operating Lease Asset and Related Obligations
Operating Lease Assets, Noncurrent	88.2		88.2
Public Service Co Of Oklahoma [Member]
Lease Rental Costs
Operating Lease, Cost	2.0		3.5
Finance Lease Right-of-Use Asset Amortization	0.7		1.4
Interest Expense on Finance Leases	0.2		0.3
Total Lease Rental Costs	$ 2.9		$ 5.2
Supplemental Information Related to Leases
Weighted-Average Remaining Lease Term, Operating Leases	7 years 1 month 13 days		7 years 1 month 13 days
Weighted Average Remaining Lease Term, Finance Leases	6 years 7 days		6 years 7 days
Weighted Average Discount Rate, Operating Leases	3.71%		3.71%
Weighted Average Discount Rate, Finance Leases	4.77%		4.77%
Operating Cash Flows from Operating Leases			$ 3.2
Operating Cash Flows from Finance Leases			0.3
Financing Cash Flows from Finance Leases			1.5		1.8
Non-cash Acquisitions Under Operating Leases			6.2
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Generation	$ 1,566.5		1,566.5				1,577.0
Other Property, Plant and Equipment	313.5		313.5				303.5
Total Property, Plant and Equipment	5,527.6		5,527.6				5,439.6
Accumulated Amortization	1,527.2		1,527.2				1,472.9
Net Property, Plant and Equipment Under Finance Leases	13.1		13.1
Obligations Under Finance Leases Noncurrent	28.9		28.9				32.5
Finance Lease Liability Due Within One Year	64.2		64.2				64.5
Total Obligations Under Finance Leases	13.1		13.1
Operating Lease Asset and Related Obligations
Operating Lease Assets	35.1		35.1				0.0
Operating Lease Assets, Noncurrent	471.3		471.3				407.8
Operating Lease Noncurrent Liability	29.3		29.3				0.0
Operating Lease Liability Due Within One Year	5.9		5.9				0.0
Total Obligations Under Operating Leases	35.2		35.2
Finance Lease Liabilities Rolling Future Minimum Lease Payments
Finance Leases, Year 1	3.6		3.6
Finance Leases, Year 2	2.9		2.9
Finance Leases, Year 3	2.2		2.2
Finance Leases, Year 4	1.8		1.8
Finance Leases, Year 5	1.5		1.5
Finance Leases, Later Years	3.4		3.4
Finance Leases, Total Future Minimum Lease Payments	15.4		15.4
Imputed Interest on Finance Leases	2.3		2.3
Total Obligations Under Finance Leases	13.1		13.1
Operating Lease Liabilities Rolling Future Minimum Lease Payments
Operating Leases, Year 1	7.0		7.0
Operating Leases, Year 2	6.4		6.4
Operating Leases, Year 3	5.6		5.6
Operating Leases, Year 4	5.2		5.2
Operating Leases, Year 5	4.6		4.6
Operating Leases, Later Years	12.0		12.0
Operating Leases, Total Future Minimum Lease Payments	40.8		40.8
Imputed Interest on Operating Leases	5.6		5.6
Estimated Present Value of Future Minimum Lease Payments on Operating Leases	35.2		35.2
Finance Lease Future Minimum Lease Payments
Capital Leases, 2019							3.4
Capital Leases, 2020							2.6
Capital Leases, 2021							2.0
Capital Leases, 2022							1.6
Capital Leases, 2023							1.4
Capital Leases, Later Years							3.3
Capital Leases, Total Future Minimum Payments Due							14.3
Estimated Interest Element on Capital Leases							2.0
Estimated Present Value of Future Minimum Lease Payments on Capital Leases							12.3
Operating Lease Future Minimum Lease Payments
Noncancelable Operating Leases, 2019							6.5
Noncancelable Operating Leases, 2020							6.0
Noncancelable Operating Leases, 2021							5.0
Noncancelable Operating Leases, 2022							4.6
Noncancelable Operating Leases, 2023							4.1
Noncancelable Operating Leases, Later Years							10.7
Noncancelable Operating Leases Total Future Minimum Lease Payments							36.9
Maximum Potential Loss
Max Potential Loss on Master Lease Agreements	4.1		4.1
Public Service Co Of Oklahoma [Member] | Finance Lease Assets [Member]
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Generation	2.6		2.6
Other Property, Plant and Equipment	19.1		19.1
Total Property, Plant and Equipment	21.7		21.7
Accumulated Amortization	8.6		8.6
Public Service Co Of Oklahoma [Member] | Finance Lease Liabilities [Member]
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Obligations Under Finance Leases Noncurrent	10.0		10.0
Finance Lease Liability Due Within One Year	3.1		3.1
Southwestern Electric Power Co [Member]
Lease Rental Costs
Operating Lease, Cost	2.1		3.9
Finance Lease Right-of-Use Asset Amortization	2.7		5.4
Interest Expense on Finance Leases	0.7		1.5
Total Lease Rental Costs	$ 5.5		$ 10.8
Supplemental Information Related to Leases
Weighted-Average Remaining Lease Term, Operating Leases	6 years 8 months 1 day		6 years 8 months 1 day
Weighted Average Remaining Lease Term, Finance Leases	5 years 5 months 8 days		5 years 5 months 8 days
Weighted Average Discount Rate, Operating Leases	3.87%		3.87%
Weighted Average Discount Rate, Finance Leases	5.01%		5.01%
Operating Cash Flows from Operating Leases			$ 3.7
Operating Cash Flows from Finance Leases			1.5
Financing Cash Flows from Finance Leases			5.5		$ 5.7
Non-cash Acquisitions Under Operating Leases			7.5
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Generation	$ 4,670.4		4,670.4				4,672.6
Other Property, Plant and Equipment	698.8		698.8				762.7
Total Property, Plant and Equipment	9,760.6		9,760.6				9,680.1
Accumulated Amortization	2,805.2		2,805.2				2,808.3
Net Property, Plant and Equipment Under Finance Leases	59.8		59.8
Obligations Under Finance Leases Noncurrent	44.0		44.0				51.4
Finance Lease Liability Due Within One Year	123.7		123.7				106.4
Total Obligations Under Finance Leases	60.6		60.6
Operating Lease Asset and Related Obligations
Operating Lease Assets, Noncurrent	403.5		403.5				342.0
Operating Lease Noncurrent Liability	31.5		31.5				0.0
Operating Lease Liability Due Within One Year	6.0		6.0				0.0
Total Obligations Under Operating Leases	37.5		37.5
Finance Lease Liabilities Rolling Future Minimum Lease Payments
Finance Leases, Year 1	13.1		13.1
Finance Leases, Year 2	11.4		11.4
Finance Leases, Year 3	10.6		10.6
Finance Leases, Year 4	9.4		9.4
Finance Leases, Year 5	12.8		12.8
Finance Leases, Later Years	10.6		10.6
Finance Leases, Total Future Minimum Lease Payments	67.9		67.9
Imputed Interest on Finance Leases	7.3		7.3
Total Obligations Under Finance Leases	60.6		60.6
Operating Lease Liabilities Rolling Future Minimum Lease Payments
Operating Leases, Year 1	8.0		8.0
Operating Leases, Year 2	7.9		7.9
Operating Leases, Year 3	7.1		7.1
Operating Leases, Year 4	6.7		6.7
Operating Leases, Year 5	5.4		5.4
Operating Leases, Later Years	11.4		11.4
Operating Leases, Total Future Minimum Lease Payments	46.5		46.5
Imputed Interest on Operating Leases	9.0		9.0
Estimated Present Value of Future Minimum Lease Payments on Operating Leases	37.5		37.5
Finance Lease Future Minimum Lease Payments
Capital Leases, 2019							13.1
Capital Leases, 2020							11.5
Capital Leases, 2021							10.5
Capital Leases, 2022							9.4
Capital Leases, 2023							8.6
Capital Leases, Later Years							18.7
Capital Leases, Total Future Minimum Payments Due							71.8
Estimated Interest Element on Capital Leases							11.0
Estimated Present Value of Future Minimum Lease Payments on Capital Leases							60.8
Operating Lease Future Minimum Lease Payments
Noncancelable Operating Leases, 2019							7.4
Noncancelable Operating Leases, 2020							7.2
Noncancelable Operating Leases, 2021							6.7
Noncancelable Operating Leases, 2022							6.1
Noncancelable Operating Leases, 2023							5.0
Noncancelable Operating Leases, Later Years							11.7
Noncancelable Operating Leases Total Future Minimum Lease Payments							$ 44.1
Maximum Potential Loss
Max Potential Loss on Master Lease Agreements	4.4		4.4
Southwestern Electric Power Co [Member] | Finance Lease Assets [Member]
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Generation	34.3		34.3
Other Property, Plant and Equipment	48.3		48.3
Total Property, Plant and Equipment	82.6		82.6
Accumulated Amortization	22.8		22.8
Southwestern Electric Power Co [Member] | Finance Lease Liabilities [Member]
Property, Plant and Equipment and Other Related Obligations Under Finance Leases
Obligations Under Finance Leases Noncurrent	49.7		49.7
Finance Lease Liability Due Within One Year	10.9		10.9
Southwestern Electric Power Co [Member] | Operating Lease Assets [Member]
Operating Lease Asset and Related Obligations
Operating Lease Assets, Noncurrent	$ 37.3		$ 37.3

[1] Elimination of intercompany interest income/interest expense on affiliated debt arrangement.