Revenue From Contracts With Customers - Schedule of Revenues Disaggregated By Customer Type (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 1,068	$ 706	$ 1,861	$ 1,382
Federal, including independent agencies
Disaggregation of Revenue [Line Items]
Revenues	998		1,727
Non-federal (state, local, other)
Disaggregation of Revenue [Line Items]
Revenues	70		134
Defense and Intelligence
Disaggregation of Revenue [Line Items]
Revenues	702		1,139
Defense and Intelligence | Federal, including independent agencies
Disaggregation of Revenue [Line Items]
Revenues	700		1,136
Defense and Intelligence | Non-federal (state, local, other)
Disaggregation of Revenue [Line Items]
Revenues	2		3
Civilian and Health Care
Disaggregation of Revenue [Line Items]
Revenues	366		722
Civilian and Health Care | Federal, including independent agencies
Disaggregation of Revenue [Line Items]
Revenues	298		591
Civilian and Health Care | Non-federal (state, local, other)
Disaggregation of Revenue [Line Items]
Revenues	$ 68		$ 131