(Loss) Earnings Per Share - Schedule of Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions		2 Months Ended	3 Months Ended								10 Months Ended	12 Months Ended
	May 31, 2018	May 31, 2018	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2019	Mar. 31, 2020		Mar. 31, 2019		Mar. 31, 2018
Earnings Per Share [Abstract]
Net (loss) income		$ 49	$ (789)	$ 53	$ 29	$ 31	$ (19)	$ 38	$ 24	$ 29	$ 23	$ (676)		$ 72		$ 208
Common share information:
Weighted average common shares outstanding for basic EPS (in shares)	165,700											161,990		164,560		142,430
Dilutive effect of stock options and equity awards (in shares)												0		260		0
Weighted average common shares outstanding for diluted EPS (in shares)												161,990		164,820		142,430
(Loss) earnings per common share:
Basic (in dollars per share)			$ (4.89)	$ 0.33	$ 0.18	$ 0.19	$ (0.12)	$ 0.23	$ 0.15	$ 0.18		$ (4.17)	[1]	$ 0.44	[1]	$ 1.46	[1]
Diluted (in dollars per share)			$ (4.89)	$ 0.33	$ 0.18	$ 0.19	$ (0.12)	$ 0.23	$ 0.14	$ 0.17		$ (4.17)	[1]	$ 0.44	[1]	$ 1.46	[1]

[1] (1) Earnings per common share information for the fiscal year ended March 31, 2018 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.