Earnings Per Share - Schedule of Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions		1 Months Ended	2 Months Ended	3 Months Ended			6 Months Ended
		Jun. 30, 2018	May 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net income		$ (20)	$ 49	$ 24	$ 40	$ 32	$ 53	$ 72
Common share information:
Weighted average common shares outstanding for basic EPS (in shares)				165,490	142,430		165,540	142,430
Dilutive effect of stock options and equity awards (in shares)				300	0		280	0
Weighted average common shares outstanding for diluted EPS (in shares)				165,790	142,430		165,820	142,430
Earnings per share:
Basic (in dollars per share)	[1]			$ 0.15	$ 0.28		$ 0.32	$ 0.51
Diluted (in dollars per share)	[1]			$ 0.14	$ 0.28		$ 0.32	$ 0.51

[1] Earnings per share information for the three and six months ended September 30, 2017 is computed using the 142.43 million shares of Perspecta common stock resulting from the Distribution, as Perspecta did not operate as a stand-alone entity during the period and therefore, no Perspecta common stock, stock options or other equity awards were outstanding and no dividends were declared or paid by Perspecta.