Revenue - Adoption of 606 (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Apr. 01, 2018	Mar. 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ 5,178	$ 5,460	$ 15,473	$ 16,149
Costs of services	3,725	4,051	11,110	12,230
Selling, general, and administrative (excludes depreciation and amortization and restructuring costs)	491	447	1,500	1,484
Interest income	(27)	(27)	(92)	(59)
Income tax expense (benefit)	3	(365)	205	(303)
Net income attributable to DXC common stockholders	462	$ 776	983	$ 1,191
Assets:
Receivables, net of allowance for doubtful accounts	5,096		5,096			$ 5,481
Other current assets	325		325			469
Deferred tax assets	407		407			373
Other assets	2,393		2,393			2,404
Liabilities:
Accrued expenses and other current liabilities	3,228		3,228			3,120
Deferred revenue and advance contract payments	1,542		1,542			1,641
Income taxes payable	122		122			127
Non-current deferred revenue	273		273			795
Non-current income tax liabilities and deferred tax liabilities	1,171		1,171			1,166
Equity:
Retained earnings	274		274			1,301
Accumulated other comprehensive loss	(464)		(464)			$ 58
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	7		21
Costs of services	(1)		(4)
Selling, general, and administrative (excludes depreciation and amortization and restructuring costs)	(15)		(42)
Interest income	(3)		(10)
Income tax expense (benefit)	8		16
Net income attributable to DXC common stockholders	12		41
Assets:
Receivables, net of allowance for doubtful accounts	(13)		(13)
Other current assets	(47)		(47)
Deferred tax assets	(14)		(14)
Other assets	(70)		(70)
Liabilities:
Accrued expenses and other current liabilities	(2)		(2)
Deferred revenue and advance contract payments	(81)		(81)		$ (381)
Income taxes payable	20		20		(40)
Non-current deferred revenue	(247)		(247)
Non-current income tax liabilities and deferred tax liabilities	21		21
Equity:
Retained earnings	152		152		$ 114
Accumulated other comprehensive loss	(5)		(5)
Calculated under Revenue Guidance in Effect before Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	5,171		15,452
Costs of services	3,726		11,114
Selling, general, and administrative (excludes depreciation and amortization and restructuring costs)	506		1,542
Interest income	(30)		(102)
Income tax expense (benefit)	(5)		189
Net income attributable to DXC common stockholders	450		942
Assets:
Receivables, net of allowance for doubtful accounts	5,109		5,109
Other current assets	372		372
Deferred tax assets	421		421
Other assets	2,463		2,463
Liabilities:
Accrued expenses and other current liabilities	3,230		3,230
Deferred revenue and advance contract payments	1,623		1,623
Income taxes payable	102		102
Non-current deferred revenue	520		520
Non-current income tax liabilities and deferred tax liabilities	1,150		1,150
Equity:
Retained earnings	122		122
Accumulated other comprehensive loss	$ (459)		$ (459)