Receivables - Sale of Receivables (Details) - USD ($)	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Oct. 31, 2018	May 31, 2018	Jul. 14, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
MARPA facility term	1 year
MARPA facility extension	6 months
Sale of billed and unbilled receivables	$ 3,420,000,000	$ 2,710,000,000
Collections corresponding to sale of receivables	63,000,000	11,000,000
Amounts outstanding	255,000,000	146,000,000
Line of Credit | MARPA Facility
Accounts, Notes, Loans and Financing Receivable [Line Items]
Maximum borrowing capacity			$ 300,000,000
Perspecta Enterprise Solutions LLC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Aggregate facility limit, first amendment				$ 450,000,000	$ 200,000,000
Financial Institution
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collections corresponding to sale of receivables	$ 3,310,000,000	$ 2,750,000,000