CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (unaudited) - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Loss	Treasury Stock		Total DXC Equity	Non- Controlling Interest	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjustment Retained Earnings (Accumulated Deficit)	Cumulative Effect, Period of Adoption, Adjustment Total DXC Equity
Balance (in shares) at Mar. 31, 2019		270,214,000
Beginning balance at Mar. 31, 2019	$ 11,725	$ 3	$ 11,301	$ 478	$ (244)	$ (136)		$ 11,402	$ 323
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(1,857)			(1,874)				(1,874)	17
Other comprehensive income	77				68			68	9
Share-based compensation expense	55		55					55
Acquisition of treasury stock	(15)					(15)		(15)
Share repurchase program (in shares)		(15,934,000)
Share repurchase program	(736)		(669)	(67)				(736)
Stock option exercises and other common stock transactions (in shares)		1,326,000
Stock option exercises and other common stock transactions	14		14					14
Dividends declared	(165)			(165)				(165)
Non-controlling interest distributions and other	3							0	3
Balance (in shares) at Dec. 31, 2019		255,606,000
Ending balance at Dec. 31, 2019	9,101	$ 3	10,701	(1,628)	(176)	(151)		8,749	352
Balance (in shares) at Mar. 31, 2019		270,214,000
Beginning balance at Mar. 31, 2019	$ 11,725	$ 3	11,301	478	(244)	(136)		11,402	323
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Balance (in shares) at Mar. 31, 2020		255,674,000
Ending balance at Mar. 31, 2020	$ 5,129	$ 3	10,714	(5,177)	(603)	(152)	[1]	4,785	344	$ (4)	$ (4)	$ (4)
Balance (in shares) at Sep. 30, 2019		257,626,000
Beginning balance at Sep. 30, 2019	8,870	$ 3	10,793	(1,668)	(428)	(150)		8,550	320
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	90			82				82	8
Other comprehensive income	283				252			252	31
Share-based compensation expense	6		6					6
Acquisition of treasury stock	(1)					(1)		(1)
Share repurchase program (in shares)		(2,354,000)
Share repurchase program	(86)		(98)	12				(86)
Stock option exercises and other common stock transactions (in shares)		334,000
Dividends declared	(54)			(54)				(54)
Non-controlling interest distributions and other	(7)							0	(7)
Balance (in shares) at Dec. 31, 2019		255,606,000
Ending balance at Dec. 31, 2019	$ 9,101	$ 3	10,701	(1,628)	(176)	(151)		8,749	352
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury shares (in shares)	2,148,708
Balance (in shares) at Mar. 31, 2020		255,674,000
Beginning balance at Mar. 31, 2020	$ 5,129	$ 3	10,714	(5,177)	(603)	(152)	[1]	4,785	344	$ (4)	$ (4)	$ (4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	658			649				649	9
Other comprehensive income	199				196			196	3
Share-based compensation expense	33		33					33
Acquisition of treasury stock	(4)					(4)	[1]	(4)
Stock option exercises and other common stock transactions (in shares)		1,127,000
Stock option exercises and other common stock transactions	1		1					1
Non-controlling interest distributions and other	(17)			(1)				(1)	(16)
Balance (in shares) at Dec. 31, 2020		256,801,000
Ending balance at Dec. 31, 2020	5,995	$ 3	10,748	(4,533)	(407)	(156)	[1]	5,655	340
Balance (in shares) at Sep. 30, 2020		256,522,000
Beginning balance at Sep. 30, 2020	4,751	$ 3	10,746	(5,631)	(562)	(155)	[1]	4,401	350
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	1,103			1,098				1,098	5
Other comprehensive income	156				155			155	1
Share-based compensation expense	1		1					1
Acquisition of treasury stock	(1)					(1)	[1]	(1)
Stock option exercises and other common stock transactions (in shares)		279,000
Stock option exercises and other common stock transactions	1		1					1
Non-controlling interest distributions and other	(16)							0	(16)
Balance (in shares) at Dec. 31, 2020		256,801,000
Ending balance at Dec. 31, 2020	$ 5,995	$ 3	$ 10,748	$ (4,533)	$ (407)	$ (156)	[1]	$ 5,655	$ 340
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury shares (in shares)	2,410,917

[1] 2,410,917 treasury shares as of December 31, 2020.