Acquisitions - Fiscal 2017 Acquisitions (Details) - USD ($)		6 Months Ended
	May 05, 2016	Sep. 30, 2017	Sep. 30, 2016	Mar. 31, 2017	[1]
Business Acquisition [Line Items]
Payments for acquisitions, net of cash acquired		$ 152,000,000	$ 434,000,000
Goodwill		$ 9,158,000,000		$ 1,855,000,000
Xchanging
Business Acquisition [Line Items]
Total estimated consideration transferred	$ 693,000,000
Payments for acquisitions, net of cash acquired	492,000,000
Transaction costs	17,000,000
Current assets acquired	396,000,000
Noncurrent assets	99,000,000
Intangible assets	582,000,000
Current liabilities	267,000,000
Long-term liabilities	516,000,000
Goodwill	680,000,000
Noncontrolling interest	281,000,000
Expected tax deductible amount of goodwill acquired	$ 0
Xchanging | Developed technology | Minimum
Business Acquisition [Line Items]
Estimated Useful Lives (Years)	7 years
Xchanging | Developed technology | Maximum
Business Acquisition [Line Items]
Estimated Useful Lives (Years)	8 years
Xchanging | Customer relationships
Business Acquisition [Line Items]
Estimated Useful Lives (Years)	15 years
Xchanging | Trade names | Minimum
Business Acquisition [Line Items]
Estimated Useful Lives (Years)	3 years
Xchanging | Trade names | Maximum
Business Acquisition [Line Items]
Estimated Useful Lives (Years)	5 years

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