Revenue From Contracts With Customers - Schedule of Revenues Disaggregated By Customer Type (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 1,075	$ 722	$ 2,936	$ 2,104
Federal, including independent agencies
Disaggregation of Revenue [Line Items]
Revenues	1,009		2,736
Non-federal (state, local, other)
Disaggregation of Revenue [Line Items]
Revenues	66		200
Defense and Intelligence
Disaggregation of Revenue [Line Items]
Revenues	709		1,848
Defense and Intelligence | Federal, including independent agencies
Disaggregation of Revenue [Line Items]
Revenues	707		1,843
Defense and Intelligence | Non-federal (state, local, other)
Disaggregation of Revenue [Line Items]
Revenues	2		5
Civilian and Health Care
Disaggregation of Revenue [Line Items]
Revenues	366		1,088
Civilian and Health Care | Federal, including independent agencies
Disaggregation of Revenue [Line Items]
Revenues	302		893
Civilian and Health Care | Non-federal (state, local, other)
Disaggregation of Revenue [Line Items]
Revenues	$ 64		$ 195