Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Millions	Total	AEP Transmission Co [Member]		AEP Texas Inc. [Member]	Appalachian Power 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] AEP Transmission Co [Member]	Additional Paid-in Capital [Member] AEP Texas Inc. [Member]	Additional Paid-in Capital [Member] Appalachian Power 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] AEP Transmission Co [Member]	Retained Earnings [Member] AEP Texas Inc. [Member]	Retained Earnings [Member] Appalachian Power 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] AEP Texas Inc. [Member]	Accumulated Other Comprehensive Income [Member] Appalachian Power Co [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]	Additional Paid-in Capital [Member]
Common Stock, Dividends, Per Share, Declared	$ 0.62
Beginning Balance, Shares at Dec. 31, 2017										512,200,000
Beginning Balance at Dec. 31, 2017	$ 18,313.6			$ 2,169.9	$ 3,804.5	$ 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			$ 1,057.9	$ 1,828.7	$ 980.9	$ 838.8	$ 364.0	$ 676.6	$ 8,626.7		$ 1,124.6	$ 1,714.1	$ 1,192.2	$ 1,148.4	$ 691.5	$ 1,426.6	$ (67.8)	$ (12.6)	$ 1.3	$ (12.1)	$ 1.9	$ 2.6	$ (4.0)	$ 26.6	$ (0.4)
Members' Equity at Dec. 31, 2017		$ 2,589.9																$ 1,816.6								$ 773.3
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)
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																										$ 0.0
Capital Contributions from Parent		65.0		100.0														65.0	100.0
ASU 2018-02 Adoption	(3.0)			(0.9)	0.4	(2.4)	0.4	0.5	(1.3)																14.0		1.8	0.1	0.3			(0.4)	(17.0)	(2.7)	0.3	(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																454.4							11.8
Net Income Attributable to Noncontrolling Interests	2.3								1.6																															2.3	1.6
Net Income (Loss)	456.7	84.1	[1]	46.8	125.5	64.2	79.6	(7.2)	13.4																	84.1	46.8	125.5	64.2	79.6	(7.2)
Other Comprehensive Income (Loss)	1.3			0.3	(1.0)	0.4	(0.3)	(0.2)	0.1																								1.3	0.3	(1.0)	0.4	(0.3)	(0.2)	0.1
Ending Balance at Mar. 31, 2018	$ 18,511.6			2,316.1	3,889.4	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			1,157.9	1,828.7	980.9	838.8	364.0	676.6	8,801.5		1,173.2	1,799.7	1,223.2	1,115.5	671.8	1,418.0	(95.4)	(15.0)	0.6	(14.4)	2.0	2.9	(4.8)	28.3	0.4
Members' Equity at Mar. 31, 2018		2,739.0																1,881.6								857.4
Ending Balance, Shares at Mar. 31, 2018										512,700,000
Common Stock, Dividends, Per Share, Declared	$ 0.67
Beginning Balance, Shares at Dec. 31, 2018	513,450,036							10,482,000		513,500,000
Beginning Balance at Dec. 31, 2018	$ 19,059.4			2,580.5	4,006.1	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			1,257.9	1,828.7	980.9	838.8	364.0	676.6	9,325.3		1,337.7	1,922.0	1,329.1	1,136.4	724.7	1,508.4	(120.4)	(15.1)	(5.0)	(13.8)	1.0	2.1	(5.4)	31.0	0.3
Members' Equity at Dec. 31, 2018		3,569.8																2,480.6								1,089.2
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)
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)	[2]																							1.0		$ 62.1	[2]
Capital Contributions from Parent		0.0		200.0															200.0
Net Income (Loss)	572.8								27.8																572.8							27.8
Net Income Attributable to Noncontrolling Interests	1.3								1.2																															1.3	1.2
Net Income (Loss)	574.1	104.3		34.4	133.7	98.9	128.0	6.2	29.0																	104.3	34.4	133.7	98.9	128.0	6.2
Other Comprehensive Income (Loss)	(30.3)			0.3	(0.8)	0.4	(0.3)	(0.2)	0.1																								(30.3)	0.3	(0.8)	0.4	(0.3)	(0.2)	0.1
Ending Balance at Mar. 31, 2019	$ 19,228.5			$ 2,815.2	$ 4,089.0	$ 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			$ 1,457.9	$ 1,828.7	$ 980.9	$ 838.8	$ 364.0	$ 676.6	$ 9,565.6		$ 1,372.1	$ 2,005.7	$ 1,408.0	$ 1,239.4	$ 719.6	$ 1,517.5	$ (150.7)	$ (14.8)	$ (5.8)	$ (13.4)	$ 0.7	$ 1.9	$ (5.3)	$ 32.2	$ 0.4
Members' Equity at Mar. 31, 2019		$ 3,674.1																$ 2,480.6								$ 1,193.5
Ending Balance, Shares at Mar. 31, 2019	513,632,124							10,482,000		513,600,000

[1] The amounts presented reflect the revisions made to AEPTCo’s previously issued financial statements. See the “Revisions to Previously Issued Financial Statements” section of Note 1 for additional information.

[2] Includes $(62) million related to a forward equity purchase contract associated with the issuance of Equity Units. See “Equity Units” section of Footnote 13 - Financing Activities.