Stockholders' Equity - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	6 Months Ended
	Sep. 30, 2017		Sep. 30, 2016
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Balance	$ 2,166	[1]	$ 2,032
Balance	12,507		2,325
Foreign Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Balance	(458)		(399)
Current-period other comprehensive income (loss)	109		(6)
Amounts reclassified from accumulated other comprehensive income	(5)		0
Balance	(354)		(405)
Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Balance	20		(1)
Current-period other comprehensive income (loss)	(5)		9
Amounts reclassified from accumulated other comprehensive income	0		0
Balance	15		8
Pension and Other Post-retirement Benefit Plans
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Balance	276		289
Current-period other comprehensive income (loss)	0		0
Amounts reclassified from accumulated other comprehensive income	(7)		(7)
Balance	269		282
Accumulated Other Comprehensive (Loss) Income
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Balance	(162)		(111)
Current-period other comprehensive income (loss)	104		3
Amounts reclassified from accumulated other comprehensive income	(12)		(7)
Balance	$ (70)		$ (115)

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