Intangible Assets - Summary of Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2017	Mar. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 10,932	$ 4,087
Accumulated Amortization	3,005	2,293	[1]
Net Carrying Value	7,927	1,794	[1]
Software
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	3,231	2,347
Accumulated Amortization	1,792	1,554
Net Carrying Value	1,439	793
Outsourcing contract costs
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,436	793
Accumulated Amortization	612	475
Net Carrying Value	824	318
Customer related intangible assets
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	6,151	851
Accumulated Amortization	583	248
Net Carrying Value	5,568	603
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	114	96
Accumulated Amortization	18	16
Net Carrying Value	$ 96	$ 80

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