Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
Effective income tax rate	29.10%	0.60%	(11.50%)	17.70%
Tax effect of discontinued operation			$ 0	$ 18
Change amount to be repatriated			498
Liability for uncertain tax positions, adjustment	$ 20
Minimum
Income Tax Contingency [Line Items]
Reasonably possible reduction in liability for uncertain tax positions	25		25
Maximum
Income Tax Contingency [Line Items]
Reasonably possible reduction in liability for uncertain tax positions	28		28
Perspecta
Income Tax Contingency [Line Items]
Tax indemnification receivable	77		77
Tax indemnification payable	64		64
HPES
Income Tax Contingency [Line Items]
Tax indemnification payable	132		132
Tax indemnification receivable, net	18		18
Tax indemnification receivable, tax indemnification payable	107		107
Tax indemnification receivable, uncertain tax positions	$ 43		$ 43