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Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Divestitures and Acquisitions - Statement of Operations Data Classified as Discontinued Operations (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 24, 2016	Jun. 26, 2015	Jun. 24, 2016	Jun. 26, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on sale of business		$ 2		$ (20)
NSS [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on sale of business			$ 64