CONDENSED CONSOLIDATED COMBINED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (unaudited) - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Parent Company Investment
Balance, beginning at Mar. 31, 2017	$ 416						$ 416
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Effects of purchase accounting	2,434						2,434
Net income	32						32
Effects of purchase accounting	(77)						(77)
Ending balance at Jun. 30, 2017	2,805						2,805
Balance, beginning at Mar. 31, 2017	416						416
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	72
Ending balance at Sep. 30, 2017	2,737						2,737
Balance, beginning at Jun. 30, 2017	2,805						2,805
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	40
Transfers to Parent, net from April 1 to May 31, 2018	(108)
Ending balance at Sep. 30, 2017	2,737						2,737
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact of adoption of new accounting standard	4						4
Balance (in shares) at Mar. 31, 2018		0
Balance, beginning at Mar. 31, 2018	2,729	$ 0	$ 0	$ 0	$ 0	$ 0	2,729
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	49			0			49
Transfers to Parent, net from April 1 to May 31, 2018	(145)						(145)
Dividend to DXC prior to May 31, 2018	(984)		(984)
Ending balance at May. 31, 2018	2,637	$ 0	0	0	0	0	2,637
Balance (in shares) at May. 31, 2018		0
Balance (in shares) at Mar. 31, 2018		0
Balance, beginning at Mar. 31, 2018	2,729	$ 0	0	0	0	0	2,729
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Spin-Off activity (in shares)		142,426,000
Spin-Off activity	0	$ 2	2,635				(2,637)
Mergers activity (in shares)		23,273,000
Mergers activity	578		578
Other comprehensive loss	(1)				(1)
Dividends declared ($0.05 per share)	(8)		(8)	0
Ending balance at Jun. 30, 2018	2,202	$ 2	2,221	(20)	(1)	0	0
Balance (in shares) at Jun. 30, 2018		165,699,000
Balance (in shares) at Mar. 31, 2018		0
Balance, beginning at Mar. 31, 2018	2,729	$ 0	0	0	0	0	2,729
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 53
Share repurchases (in shares)	(923,188)
Repurchases of common stock	$ (23)
Ending balance at Sep. 30, 2018	2,203	$ 2	2,219	0	5	(23)	0
Balance (in shares) at Sep. 30, 2018		164,819,000
Balance (in shares) at May. 31, 2018		0
Balance, beginning at May. 31, 2018	2,637	$ 0	0	0	0	0	2,637
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(20)			(20)
Ending balance at Jun. 30, 2018	2,202	$ 2	2,221	(20)	(1)	0	0
Balance (in shares) at Jun. 30, 2018		165,699,000
Balance (in shares) at May. 31, 2018		0
Balance, beginning at May. 31, 2018	2,637	$ 0	0	0	0	0	2,637
Ending balance at Sep. 30, 2018	2,203	$ 2	2,219	0	5	(23)	0
Balance (in shares) at Sep. 30, 2018		164,819,000
Balance (in shares) at Jun. 30, 2018		165,699,000
Balance, beginning at Jun. 30, 2018	2,202	$ 2	2,221	(20)	(1)	0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	24			24
Other comprehensive loss	6				6
Stock-based compensation	1
Share repurchases (in shares)		(923,000)
Repurchases of common stock	(23)					(23)
Stock option exercises and other common stock transactions (in shares)		43,000
Stock option exercises and other common stock transactions	1		1
Dividends declared ($0.05 per share)	(8)		(4)	(4)
Ending balance at Sep. 30, 2018	$ 2,203	$ 2	$ 2,219	$ 0	$ 5	$ (23)	$ 0
Balance (in shares) at Sep. 30, 2018		164,819,000