Goodwill (Details) $ in Millions	9 Months Ended
	Dec. 31, 2017 USD ($)
Changes in the carrying amount of goodwill by segment [Roll Forward]
Balance as of March 31, 2017, net	$ 1,855	[1]
Additions	7,316
Foreign currency translation	149
Balance as of December 31, 2017, net	9,320
GBS
Changes in the carrying amount of goodwill by segment [Roll Forward]
Balance as of March 31, 2017, net	1,470
Additions	2,800
Foreign currency translation	94
Balance as of December 31, 2017, net	4,364
GIS
Changes in the carrying amount of goodwill by segment [Roll Forward]
Balance as of March 31, 2017, net	385
Additions	2,532
Foreign currency translation	55
Balance as of December 31, 2017, net	2,972
USPS
Changes in the carrying amount of goodwill by segment [Roll Forward]
Balance as of March 31, 2017, net	0
Additions	1,984
Foreign currency translation	0
Balance as of December 31, 2017, net	$ 1,984

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