Goodwill (Details) $ in Millions	6 Months Ended
	Sep. 30, 2017 USD ($)
Changes in the carrying amount of goodwill by segment [Roll Forward]
Balance as of March 31, 2017, net	$ 1,855	[1]
Additions	7,155
Foreign currency translation	148
Balance as of September 30, 2017, net	9,158
GBS
Changes in the carrying amount of goodwill by segment [Roll Forward]
Balance as of March 31, 2017, net	1,470
Additions	2,996
Foreign currency translation	93
Balance as of September 30, 2017, net	4,559
GIS
Changes in the carrying amount of goodwill by segment [Roll Forward]
Balance as of March 31, 2017, net	385
Additions	3,423
Foreign currency translation	55
Balance as of September 30, 2017, net	3,863
USPS
Changes in the carrying amount of goodwill by segment [Roll Forward]
Balance as of March 31, 2017, net	0
Additions	736
Foreign currency translation	0
Balance as of September 30, 2017, net	$ 736

[1] Certain prior year amounts were adjusted to retroactively reflect the legal capital of DXC.