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Acquisitions - Knight Point Systems (Details) - USD ($) $ in Millions			8 Months Ended
	May 01, 2020	Jul. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Business Acquisition [Line Items]
Goodwill			$ 2,671	$ 3,179	$ 2,022
Knight Point Systems, LLC
Business Acquisition [Line Items]
Payments to acquire business		$ 250
Consideration transferred		265	264
Goodwill		116
Assets acquired		125
Defense and Intelligence
Business Acquisition [Line Items]
Goodwill			1,449	2,051	977
Defense and Intelligence \| Knight Point Systems, LLC
Business Acquisition [Line Items]
Goodwill		22
Civilian and Health Care
Business Acquisition [Line Items]
Goodwill			$ 1,222	$ 1,128	$ 1,045
Civilian and Health Care \| Knight Point Systems, LLC
Business Acquisition [Line Items]
Goodwill		94
Program assets \| Knight Point Systems, LLC
Business Acquisition [Line Items]
Assets acquired		102
Technology-based intangible assets \| Knight Point Systems, LLC
Business Acquisition [Line Items]
Assets acquired		18
Backlog \| Knight Point Systems, LLC
Business Acquisition [Line Items]
Assets acquired		$ 5
Weighted-average Amortization Period (in years)		1 year
Minimum \| Knight Point Systems, LLC
Business Acquisition [Line Items]
Weighted-average Amortization Period (in years)		10 years
Minimum \| Technology-based intangible assets \| Knight Point Systems, LLC
Business Acquisition [Line Items]
Weighted-average Amortization Period (in years)		7 years
Maximum \| Knight Point Systems, LLC
Business Acquisition [Line Items]
Weighted-average Amortization Period (in years)		12 years
Subsequent Event \| DHPC Technologies [Member]
Business Acquisition [Line Items]
Consideration transferred	$ 53