Acquisitions - Schedule of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions	Mar. 31, 2019	May 31, 2018	Mar. 31, 2018	Mar. 31, 2017
Business Acquisition [Line Items]
Goodwill	$ 3,179		$ 2,022	$ 0
Vencore
Business Acquisition [Line Items]
Current assets		$ 333
Property and equipment		35
Intangible assets		753
Other assets		40
Accounts payable, accrued payroll, accrued expenses, and other current liabilities		(194)
Deferred revenue		(12)
Deferred tax liabilities		(10)
Other liabilities		(119)
Net identifiable assets acquired		826
Goodwill		1,146
Total estimated consideration transferred		$ 1,972