Revenue From Contracts With Customers - Schedule of Revenues Disaggregated By Prime or Subcontractor (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
Prime contractor
Disaggregation of Revenue [Line Items]
Revenues	992		2,719
Subcontractor
Disaggregation of Revenue [Line Items]
Revenues	83		217
Defense and Intelligence
Disaggregation of Revenue [Line Items]
Revenues	709		1,848
Defense and Intelligence | Prime contractor
Disaggregation of Revenue [Line Items]
Revenues	663		1,740
Defense and Intelligence | Subcontractor
Disaggregation of Revenue [Line Items]
Revenues	46		108
Civilian and Health Care
Disaggregation of Revenue [Line Items]
Revenues	366		1,088
Civilian and Health Care | Prime contractor
Disaggregation of Revenue [Line Items]
Revenues	329		979
Civilian and Health Care | Subcontractor
Disaggregation of Revenue [Line Items]
Revenues	$ 37		$ 109