Financial Instruments (Details) (Narrative) - USD ($) $ in Millions	Jun. 27, 2015	Dec. 27, 2014
Money Market Funds
Financial Instruments [Line Items]
Available-for-sale investments used as collateral		$ 10
Mutual Funds
Financial Instruments [Line Items]
Restricted investments	$ 16	$ 16

The fair value of available-for-sale securities that serve as collateral for borrowings.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5086-111524

Name:	us-gaap_AvailableForSaleSecuritiesPledgedAsCollateral
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant