Business Segments - Assets and Revenues by Business Segments (Details) $ in Millions	3 Months Ended
	Sep. 29, 2017 USD ($) segment	Jun. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)
Segment Reporting Information [Line Items]
Total assets	$ 10,099	$ 10,090
Identifiable intangible assets	$ 1,077	1,104
Number of remaining segments | segment	3
Income From Continuing Operations Before Income Taxes
Revenue	$ 1,413		$ 1,420
Segment operating income	272		246
Non-operating income	0		1
Net interest expense	(41)		(44)
Income from continuing operations before income taxes	231		203
Operating Segments | Communication Systems
Segment Reporting Information [Line Items]
Total assets	1,588	1,534
Income From Continuing Operations Before Income Taxes
Revenue	410		430
Segment operating income	118		118
Operating Segments | Electronic Systems
Segment Reporting Information [Line Items]
Total assets	4,123	4,094
Income From Continuing Operations Before Income Taxes
Revenue	540		537
Segment operating income	109		111
Operating Segments | Space and Intelligence Systems
Segment Reporting Information [Line Items]
Total assets	2,159	2,117
Income From Continuing Operations Before Income Taxes
Revenue	466		453
Segment operating income	87		79
Corporate eliminations
Segment Reporting Information [Line Items]
Total assets	2,229	2,345
Income From Continuing Operations Before Income Taxes
Revenue	(3)		0
Segment operating income	(1)		(1)
Corporate eliminations | Exelis
Segment Reporting Information [Line Items]
Identifiable intangible assets	1,100	1,100
Unallocated corporate income (expense)
Income From Continuing Operations Before Income Taxes
Segment operating income	$ (41)		(61)
Unallocated corporate income (expense) | Exelis
Income From Continuing Operations Before Income Taxes
Business combination, integration and other costs			17
Amortization of Intangible Assets		$ 25	$ 27