Goodwill (Details) $ in Millions	9 Months Ended
	Dec. 31, 2018 USD ($)
Changes in the carrying amount of goodwill by segment [Roll Forward]
Balance as of March 31, 2018	$ 2,022
Additions	1,239
Allocations from DXC	11
Balance as of December 31, 2018	3,272
Defense and Intelligence
Changes in the carrying amount of goodwill by segment [Roll Forward]
Balance as of March 31, 2018	977
Additions	1,156
Allocations from DXC	11
Balance as of December 31, 2018	2,144
Civilian and Health Care
Changes in the carrying amount of goodwill by segment [Roll Forward]
Balance as of March 31, 2018	1,045
Additions	83
Allocations from DXC	0
Balance as of December 31, 2018	$ 1,128