Acquisitions - Schedule of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions	Dec. 31, 2018	May 31, 2018	Mar. 31, 2018
Business Acquisition [Line Items]
Goodwill	$ 3,272		$ 2,022
Vencore
Business Acquisition [Line Items]
Current assets		$ 333
Property and equipment		35
Intangible assets		622
Other assets		33
Accounts payable, accrued payroll, accrued expenses, and other current liabilities		(188)
Deferred revenue		(12)
Other liabilities		(90)
Net identifiable assets acquired		733
Goodwill		1,239
Consideration transferred		$ 1,972