Acquisitions - HPES Merger Additional Information (Details) $ in Millions			3 Months Ended			6 Months Ended
	Sep. 25, 2017 USD ($)	Apr. 01, 2017 USD ($) employee shares	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Mar. 31, 2017 USD ($) tranche		May 31, 2016 USD ($)
Business Acquisition [Line Items]
Amortization expense			$ 310		$ 82	$ 514	$ 162
Goodwill			9,158			9,158		$ 1,855	[1]
Net income			265		21	438	1
GBS
Business Acquisition [Line Items]
Goodwill			4,559			4,559		1,470
GIS
Business Acquisition [Line Items]
Goodwill			3,863			3,863		385
USPS
Business Acquisition [Line Items]
Goodwill			736			736		0
HPES
Business Acquisition [Line Items]
Shares issued for each share of CSC common stock (in shares) | shares		1
Shares issued for merger consideration (in shares) | shares		141,298,797
Percent ownership of CSC stockholders following the Merger		49.90%
Adjustment to settle obligations	$ 175
Adjustment to capital lease obligation			977
Adjustment to property, plant, and equipment			436
Adjustment to net assets			(312)
Adjustment to assets			1,300
Adjustment to accounts receivable			94
Adjustment to indemnification assets			85
Adjustment to intangible assets			1,100
Adjustment to liabilities			1,600
Adjustment to deferred revenue			226
Adjustment to deferred taxes, noncurrent			106
Goodwill		$ 7,077
Acquired restructuring liabilities		333
Long-term debt		4,783
Adjustment to debt			94
Adjustment to deferred debt issuance costs, premiums and discounts			12
Capital lease obligation			1,600			1,600
Net income					$ 1		$ 26
HPES | Employee severance
Business Acquisition [Line Items]
Acquired restructuring liabilities		256
HPES | Facilities costs
Business Acquisition [Line Items]
Acquired restructuring liabilities		77
HPES | GBS
Business Acquisition [Line Items]
Goodwill		2,900
HPES | GIS
Business Acquisition [Line Items]
Goodwill		3,500
HPES | USPS
Business Acquisition [Line Items]
Goodwill		$ 700
HPES | Senior notes
Business Acquisition [Line Items]
Long-term debt								1,800
HPES | Senior notes | Senior Notes Issued 2017
Business Acquisition [Line Items]
Long-term debt								1,500
HPES | Senior notes | Senior Notes Issued 1999
Business Acquisition [Line Items]
Long-term debt								300
HPES | Term Loan
Business Acquisition [Line Items]
Long-term debt								$ 2,000
Number of tranches | tranche								3
Director | HPES
Business Acquisition [Line Items]
Entity directors | employee		10
Computer Sciences Corporation | Director | HPES
Business Acquisition [Line Items]
Entity directors | employee		5
Hewlett Packard Enterprise Company | Director | HPES
Business Acquisition [Line Items]
Entity directors | employee		5
Customer relationships | HPES
Business Acquisition [Line Items]
Adjustment to intangible assets			1,300
Assets Held under Capital Leases | HPES
Business Acquisition [Line Items]
Adjustment to property, plant, and equipment			594
Adjustment to goodwill			383
Land and Data Centers | HPES
Business Acquisition [Line Items]
Adjustment to property, plant, and equipment			(152)
Accounting Standards Update 2015-16 | HPES
Business Acquisition [Line Items]
Adjustment to cost of sales			209
Adjustment to depreciation			88
Adjustment to interest expense			13
Adjustment due to capital to operating lease conversion			54
Income (loss) before income taxes				$ 48
Adjustment to fair value of deferred revenue net of deferred cost			8
Depreciation			10
Amortization expense			(18)
Accounting Standards Update 2015-16 | Vendor contracts | HPES
Business Acquisition [Line Items]
Change in fair value of intangible assets			$ (10)			$ (10)
Maximum | HPES | HPES
Business Acquisition [Line Items]
Lease obligation										$ 250

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