Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Millions	Total	Appalachian Power Co [Member]	AEP Texas Inc. [Member]	AEP Transmission Co [Member]	Indiana Michigan Power Co [Member]	Ohio Power Co [Member]	Public Service Co Of Oklahoma [Member]	Southwestern Electric Power Co [Member]	Common Stock [Member]	Common Stock [Member] Appalachian Power Co [Member]	Common Stock [Member] Indiana Michigan Power Co [Member]	Common Stock [Member] Ohio Power Co [Member]	Common Stock [Member] Public Service Co Of Oklahoma [Member]	Common Stock [Member] Southwestern Electric Power Co [Member]	Additional Paid-in Capital [Member]		Additional Paid-in Capital [Member] Appalachian Power Co [Member]	Additional Paid-in Capital [Member] AEP Texas Inc. [Member]	Additional Paid-in Capital [Member] AEP Transmission Co [Member]	Additional Paid-in Capital [Member] Indiana Michigan Power Co [Member]	Additional Paid-in Capital [Member] Ohio Power Co [Member]	Additional Paid-in Capital [Member] Public Service Co Of Oklahoma [Member]	Additional Paid-in Capital [Member] Southwestern Electric Power Co [Member]	Retained Earnings [Member]		Retained Earnings [Member] Appalachian Power Co [Member]	Retained Earnings [Member] AEP Texas Inc. [Member]	Retained Earnings [Member] AEP Transmission Co [Member]	Retained Earnings [Member] Indiana Michigan Power Co [Member]	Retained Earnings [Member] Ohio Power Co [Member]	Retained Earnings [Member] Public Service Co Of Oklahoma [Member]	Retained Earnings [Member] Southwestern Electric Power Co [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Other Comprehensive Income [Member] Appalachian Power Co [Member]	Accumulated Other Comprehensive Income [Member] AEP Texas Inc. [Member]	Accumulated Other Comprehensive Income [Member] Indiana Michigan Power Co [Member]	Accumulated Other Comprehensive Income [Member] Ohio Power Co [Member]	Accumulated Other Comprehensive Income [Member] Public Service Co Of Oklahoma [Member]	Accumulated Other Comprehensive Income [Member] Southwestern Electric Power Co [Member]	Noncontrolling Interests [Member]	Noncontrolling Interests [Member] Southwestern Electric Power Co [Member]	AEP Wind Holdings LLC [Member]	AEP Wind Holdings LLC [Member] Noncontrolling Interests [Member]	Santa Rita East [Member]	Santa Rita East [Member] Noncontrolling Interests [Member]
Beginning Balance at Dec. 31, 2017				$ 2,589.9															$ 1,816.6									$ 773.3
Beginning Balance at Dec. 31, 2017	$ 18,313.6	$ 3,804.5	$ 2,169.9		$ 2,217.6	$ 2,310.3	$ 1,215.3	$ 2,234.5	$ 3,329.4	$ 260.4	$ 56.6	$ 321.2	$ 157.2	$ 135.7	$ 6,398.7		$ 1,828.7	$ 1,057.9		$ 980.9	$ 838.8	$ 364.0	$ 676.6	$ 8,626.7		$ 1,714.1	$ 1,124.6		$ 1,192.2	$ 1,148.4	$ 691.5	$ 1,426.6	$ (67.8)	$ 1.3	$ (12.6)	$ (12.1)	$ 1.9	$ 2.6	$ (4.0)	$ 26.6	$ (0.4)
Beginning Balance, Shares at Dec. 31, 2017									512,200,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock, Value	32.2								$ 3.3						28.9
Issuance of Common Stock, Shares									500,000
Common Stock Dividends	(306.1)																							(305.5)	[1]
Common Stock Dividends		(40.0)			(33.5)	(112.5)	(12.5)	(20.0)																		(40.0)			(33.5)	(112.5)	(12.5)	(20.0)
Common Stock Dividends								(0.8)																																(0.6)	(0.8)
Other Changes in Equity	16.9														16.9
Capital Contribution from Member			100.0	65.0														100.0	65.0
ASU 2018-02 Adoption	(3.0)	0.4	(0.9)		(2.4)	0.4	0.5	(1.3)																14.0		0.1	1.8		0.3			(0.4)	(17.0)	0.3	(2.7)	(2.7)	0.4	0.5	(0.9)
ASU 2016-01 Adoption	0.0																							11.9									(11.9)
Net Income (Loss)																								454.4								11.8
Net Income (Loss) Attributable to Noncontrolling Interests																																								2.3	1.6
Net Income (Loss)	456.7	125.5	46.8	84.1	64.2	79.6	(7.2)	13.4																		125.5	46.8	84.1	64.2	79.6	(7.2)
Other Comprehensive Income (Loss)	1.3	(1.0)	0.3		0.4	(0.3)	(0.2)	0.1																									1.3	(1.0)	0.3	0.4	(0.3)	(0.2)	0.1
Ending Balance at Mar. 31, 2018				2,739.0															1,881.6									857.4
Ending Balance at Mar. 31, 2018	$ 18,511.6	3,889.4	2,316.1		2,246.3	2,277.5	1,195.9	2,225.9	$ 3,332.7	260.4	56.6	321.2	157.2	135.7	6,444.5		1,828.7	1,157.9		980.9	838.8	364.0	676.6	8,801.5		1,799.7	1,173.2		1,223.2	1,115.5	671.8	1,418.0	(95.4)	0.6	(15.0)	(14.4)	2.0	2.9	(4.8)	28.3	0.4
Ending Balance, Shares at Mar. 31, 2018									512,700,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends Per Share, Declared	$ 0.62
Beginning Balance at Dec. 31, 2017				2,589.9															1,816.6									773.3
Beginning Balance at Dec. 31, 2017	$ 18,313.6	3,804.5	2,169.9		2,217.6	2,310.3	1,215.3	2,234.5	$ 3,329.4	260.4	56.6	321.2	157.2	135.7	6,398.7		1,828.7	1,057.9		980.9	838.8	364.0	676.6	8,626.7		1,714.1	1,124.6		1,192.2	1,148.4	691.5	1,426.6	(67.8)	1.3	(12.6)	(12.1)	1.9	2.6	(4.0)	26.6	(0.4)
Beginning Balance, Shares at Dec. 31, 2017									512,200,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
ASU 2018-02 Adoption																																	(17.0)	0.3	(2.7)	(2.7)			(0.9)
ASU 2016-01 Adoption																																	(11.9)
Net Income (Loss)	1,560.4							137.6
Net Income (Loss) Attributable to Noncontrolling Interests	6.1							4.1
Net Income (Loss)	1,566.5	290.0	151.1	244.2	231.6	237.1	89.8	141.7
Other Comprehensive Income (Loss)	10.7	(3.0)	0.9		1.2			2.6
Ending Balance at Sep. 30, 2018				3,416.1															2,398.6									1,017.5
Ending Balance at Sep. 30, 2018	19,046.8	3,971.9	2,421.0		2,342.5	2,209.3	1,267.4	2,314.3	$ 3,336.5	260.4	56.6	321.2	157.2	135.7	6,472.6		1,828.7	1,157.9		980.9	838.8	364.0	676.6	9,293.7		1,884.2	1,277.5		1,318.6	1,048.0	743.8	1,503.8	(86.0)	(1.4)	(14.4)	(13.6)	1.3	2.4	(2.3)	30.0	0.5
Ending Balance, Shares at Sep. 30, 2018									513,300,000
Beginning Balance at Mar. 31, 2018				2,739.0															1,881.6									857.4
Beginning Balance at Mar. 31, 2018	18,511.6	3,889.4	2,316.1		2,246.3	2,277.5	1,195.9	2,225.9	$ 3,332.7	260.4	56.6	321.2	157.2	135.7	6,444.5		1,828.7	1,157.9		980.9	838.8	364.0	676.6	8,801.5		1,799.7	1,173.2		1,223.2	1,115.5	671.8	1,418.0	(95.4)	0.6	(15.0)	(14.4)	2.0	2.9	(4.8)	28.3	0.4
Beginning Balance, Shares at Mar. 31, 2018									512,700,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock, Value	18.7								$ 2.7						16.0
Issuance of Common Stock, Shares									400,000
Common Stock Dividends	(308.1)																							(306.8)	[1]
Common Stock Dividends		(40.0)			(33.5)	(112.5)	(12.5)	(20.0)																		(40.0)			(33.5)	(112.5)	(12.5)	(20.0)
Common Stock Dividends								(1.0)																																(1.3)	(1.0)
Other Changes in Equity	(1.5)														(1.9)																									0.4
Capital Contribution from Member				312.0															312.0
Net Income (Loss)																								528.4								37.6
Net Income (Loss) Attributable to Noncontrolling Interests																																								1.7	1.1
Net Income (Loss)	530.1	77.4	46.5	82.0	94.7	68.8	36.6	38.7																		77.4	46.5	82.0	94.7	68.8	36.6
Other Comprehensive Income (Loss)	0.6	(1.0)	0.3		0.5	(0.3)	(0.3)	0.1																									0.6	(1.0)	0.3	0.5	(0.3)	(0.3)	0.1
Ending Balance at Jun. 30, 2018				3,133.0															2,193.6									939.4
Ending Balance at Jun. 30, 2018	$ 18,751.4	3,925.8	2,362.9		2,308.0	2,233.5	1,219.7	2,243.7	$ 3,335.4	260.4	56.6	321.2	157.2	135.7	6,458.6		1,828.7	1,157.9		980.9	838.8	364.0	676.6	9,023.1		1,837.1	1,219.7		1,284.4	1,071.8	695.9	1,435.6	(94.8)	(0.4)	(14.7)	(13.9)	1.7	2.6	(4.7)	29.1	0.5
Ending Balance, Shares at Jun. 30, 2018									513,100,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends Per Share, Declared	$ 0.62
Issuance of Common Stock, Value	$ 11.6								$ 1.1						10.5
Issuance of Common Stock, Shares									200,000
Common Stock Dividends	(308.3)																							(307.0)	[1]
Common Stock Dividends		(40.0)			(38.5)	(112.5)	(12.5)	(20.0)																		(40.0)			(38.5)	(112.5)	(12.5)	(20.0)
Common Stock Dividends								(1.4)																																(1.3)	(1.4)
Other Changes in Equity	3.6														3.5																									0.1
Capital Contribution from Member				205.0															205.0
Net Income (Loss)	577.6							88.2																577.6								88.2
Net Income (Loss) Attributable to Noncontrolling Interests	2.1							1.4																																2.1	1.4
Net Income (Loss)	579.7	87.1	57.8	78.1	72.7	88.7	60.4	89.6																		87.1	57.8	78.1	72.7	88.7	60.4
Other Comprehensive Income (Loss)	8.8	(1.0)	0.3		0.3	(0.4)	(0.2)	2.4																									8.8	(1.0)	0.3	0.3	(0.4)	(0.2)	2.4
Ending Balance at Sep. 30, 2018				3,416.1															2,398.6									1,017.5
Ending Balance at Sep. 30, 2018	$ 19,046.8	3,971.9	2,421.0		2,342.5	2,209.3	1,267.4	2,314.3	$ 3,336.5	260.4	56.6	321.2	157.2	135.7	6,472.6		1,828.7	1,157.9		980.9	838.8	364.0	676.6	9,293.7		1,884.2	1,277.5		1,318.6	1,048.0	743.8	1,503.8	(86.0)	(1.4)	(14.4)	(13.6)	1.3	2.4	(2.3)	30.0	0.5
Ending Balance, Shares at Sep. 30, 2018									513,300,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends Per Share, Declared	$ 0.62
Beginning Balance at Dec. 31, 2018				3,569.8															2,480.6									1,089.2
Beginning Balance at Dec. 31, 2018	$ 19,059.4	4,006.1	2,580.5		2,352.8	2,297.4	$ 1,248.0	2,315.6	$ 3,337.4	260.4	56.6	321.2	157.2	135.7	6,486.1		1,828.7	1,257.9		980.9	838.8	364.0	676.6	9,325.3		1,922.0	1,337.7		1,329.1	1,136.4	724.7	1,508.4	(120.4)	(5.0)	(15.1)	(13.8)	1.0	2.1	(5.4)	31.0	0.3
Beginning Balance, Shares at Dec. 31, 2018	513,450,036						10,482,000		513,500,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock, Value	$ 14.5								$ 1.2						13.3
Issuance of Common Stock, Shares									100,000
Common Stock Dividends	(333.6)																							(332.5)	[2]
Common Stock Dividends		(50.0)			(20.0)	(25.0)	$ (11.3)	(18.7)																		(50.0)			(20.0)	(25.0)	(11.3)	(18.7)
Common Stock Dividends								(1.1)																																(1.1)	(1.1)
Other Changes in Equity	(55.6)														(56.6)	[3]																								1.0
Capital Contribution from Member			200.0															200.0
Net Income (Loss)																								572.8								27.8
Net Income (Loss) Attributable to Noncontrolling Interests																																								1.3	1.2
Net Income (Loss)	574.1	133.7	34.4	104.3	98.9	128.0	6.2	29.0																		133.7	34.4	104.3	98.9	128.0	6.2
Other Comprehensive Income (Loss)	(30.3)	(0.8)	0.3		0.4	(0.3)	(0.2)	0.1																									(30.3)	(0.8)	0.3	0.4	(0.3)	(0.2)	0.1
Ending Balance at Mar. 31, 2019				3,674.1															2,480.6									1,193.5
Ending Balance at Mar. 31, 2019	$ 19,228.5	4,089.0	2,815.2		2,432.1	2,400.1	1,242.7	2,324.9	$ 3,338.6	260.4	56.6	321.2	157.2	135.7	6,442.8		1,828.7	1,457.9		980.9	838.8	364.0	676.6	9,565.6		2,005.7	1,372.1		1,408.0	1,239.4	719.6	1,517.5	(150.7)	(5.8)	(14.8)	(13.4)	0.7	1.9	(5.3)	32.2	0.4
Ending Balance, Shares at Mar. 31, 2019									513,600,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends Per Share, Declared	$ 0.67
Beginning Balance at Dec. 31, 2018				3,569.8															2,480.6									1,089.2
Beginning Balance at Dec. 31, 2018	$ 19,059.4	4,006.1	2,580.5		2,352.8	2,297.4	$ 1,248.0	2,315.6	$ 3,337.4	260.4	56.6	321.2	157.2	135.7	6,486.1		1,828.7	1,257.9		980.9	838.8	364.0	676.6	9,325.3		1,922.0	1,337.7		1,329.1	1,136.4	724.7	1,508.4	(120.4)	(5.0)	(15.1)	(13.8)	1.0	2.1	(5.4)	31.0	0.3
Beginning Balance, Shares at Dec. 31, 2018	513,450,036						10,482,000		513,500,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Changes in Equity																								(62.0)
Net Income (Loss)	$ 1,767.6							144.5
Net Income (Loss) Attributable to Noncontrolling Interests	(0.5)							3.1
Net Income (Loss)	1,767.1	293.5	192.0	347.9	248.0	247.7	$ 148.4	147.6
Other Comprehensive Income (Loss)	(67.5)	(2.6)	0.9		1.1			0.2
Ending Balance at Sep. 30, 2019				3,917.7															2,480.6									1,437.1
Ending Balance at Sep. 30, 2019	$ 19,997.7	4,172.0	2,973.4		2,541.9	2,459.1	$ 1,384.4	2,422.6	$ 3,341.9	260.4	56.6	321.2	157.2	135.7	6,467.1		1,828.7	1,457.9		980.9	838.8	364.0	676.6	10,095.3		2,090.5	1,529.7		1,517.1	1,299.1	861.8	1,615.4	(187.9)	(7.6)	(14.2)	(12.7)	0.0	1.4	(5.2)	281.3	0.1
Ending Balance, Shares at Sep. 30, 2019	514,140,235						10,482,000		514,100,000
Beginning Balance at Mar. 31, 2019				3,674.1															2,480.6									1,193.5
Beginning Balance at Mar. 31, 2019	$ 19,228.5	4,089.0	2,815.2		2,432.1	2,400.1	$ 1,242.7	2,324.9	$ 3,338.6	260.4	56.6	321.2	157.2	135.7	6,442.8		1,828.7	1,457.9		980.9	838.8	364.0	676.6	9,565.6		2,005.7	1,372.1		1,408.0	1,239.4	719.6	1,517.5	(150.7)	(5.8)	(14.8)	(13.4)	0.7	1.9	(5.3)	32.2	0.4
Beginning Balance, Shares at Mar. 31, 2019									513,600,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock, Value	17.8								$ 2.2						15.6
Issuance of Common Stock, Shares									400,000
Common Stock Dividends	(334.5)																							(332.7)	[2]
Common Stock Dividends		(50.0)			(20.0)	(60.0)		(18.8)																		(50.0)			(20.0)	(60.0)		(18.8)
Common Stock Dividends								(1.1)																																(1.8)	(1.1)
Other Changes in Equity	2.5														3.1																									(0.6)
Acquisition																																										$ 134.8	$ 134.8
Net Income (Loss)																								461.3								6.2
Net Income (Loss) Attributable to Noncontrolling Interests																																								(2.2)	1.1
Net Income (Loss)	459.1	55.5	80.6	136.0	60.3	50.6	41.9	7.3																		55.5	80.6	136.0	60.3	50.6	41.9
Other Comprehensive Income (Loss)	(80.0)	(0.9)	0.3		0.3	(0.4)	(0.3)	0.1																									(80.0)	(0.9)	0.3	0.3	(0.4)	(0.3)	0.1
Ending Balance at Jun. 30, 2019				3,810.1															2,480.6									1,329.5
Ending Balance at Jun. 30, 2019	$ 19,423.2	4,093.6	2,896.1		2,472.7	2,390.3	1,284.3	2,312.4	$ 3,340.8	260.4	56.6	321.2	157.2	135.7	6,455.3		1,828.7	1,457.9		980.9	838.8	364.0	676.6	9,694.2		2,011.2	1,452.7		1,448.3	1,230.0	761.5	1,504.9	(230.7)	(6.7)	(14.5)	(13.1)	0.3	1.6	(5.2)	163.6	0.4
Ending Balance, Shares at Jun. 30, 2019									514,000,000.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends Per Share, Declared	$ 0.67
Issuance of Common Stock, Value	$ 12.4								$ 1.1						11.3
Issuance of Common Stock, Shares									100,000
Common Stock Dividends	(333.9)																							(332.4)	[2]
Common Stock Dividends		(25.0)			(20.0)																					(25.0)			(20.0)
Common Stock Dividends								(1.1)																																(1.5)	(1.1)
Other Changes in Equity	0.5														0.5
Acquisition																																												$ 118.8	$ 118.8
Net Income (Loss)	733.5							110.5																733.5								110.5
Net Income (Loss) Attributable to Noncontrolling Interests	0.4							0.8																																0.4	0.8
Net Income (Loss)	733.9	104.3	77.0	107.6	88.8	69.1	100.3	111.3																		104.3	77.0	107.6	88.8	69.1	100.3
Other Comprehensive Income (Loss)	42.8	(0.9)	0.3		0.4	(0.3)	(0.2)	0.0																									42.8	(0.9)	0.3	0.4	(0.3)	(0.2)
Ending Balance at Sep. 30, 2019				$ 3,917.7															$ 2,480.6									$ 1,437.1
Ending Balance at Sep. 30, 2019	$ 19,997.7	$ 4,172.0	$ 2,973.4		$ 2,541.9	$ 2,459.1	$ 1,384.4	$ 2,422.6	$ 3,341.9	$ 260.4	$ 56.6	$ 321.2	$ 157.2	$ 135.7	$ 6,467.1		$ 1,828.7	$ 1,457.9		$ 980.9	$ 838.8	$ 364.0	$ 676.6	$ 10,095.3		$ 2,090.5	$ 1,529.7		$ 1,517.1	$ 1,299.1	$ 861.8	$ 1,615.4	$ (187.9)	$ (7.6)	$ (14.2)	$ (12.7)	$ 0.0	$ 1.4	$ (5.2)	$ 281.3	$ 0.1
Ending Balance, Shares at Sep. 30, 2019	514,140,235						10,482,000		514,100,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends Per Share, Declared	$ 0.67

[1] Common Stock dividends declared per AEP common share were $0.62.

[2] Common Stock dividends declared per AEP common share were $0.67.

[3] Includes $(62) million related to a forward equity purchase contract associated with the issuance of Equity Units. See “Equity Units” section of Note 13 for additional information.