Shareholders' Equity (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 21, 2015		Mar. 22, 2014
Repurchase Of Shares Of Common Stock [Line Items]
Shares Repurchased	1,996,000	[1]	1,696,000
Dollar Value of Shares Repurchased	$ 150	[1]	$ 124
Remaining dollar value of shares that may be repurchased	983
Value Of Share Repurchases Prior To Current Reporting Date But With Settlement Dates Subsequent To Current Reporting Date	26
Share Repurchases Prior To Current Reporting Date But With Settlement Dates Subsequent To Current Reporting Date	300,000
November 2012 [Member]
Repurchase Of Shares Of Common Stock [Line Items]
Shares Repurchased	0		1,696,000
Dollar Value of Shares Repurchased	0		124
Remaining dollar value of shares that may be repurchased	0
November 2013 [Member]
Repurchase Of Shares Of Common Stock [Line Items]
Shares Repurchased	1,779,000		0
Dollar Value of Shares Repurchased	133		0
Remaining dollar value of shares that may be repurchased	0
November 2014 [Member]
Repurchase Of Shares Of Common Stock [Line Items]
Shares Repurchased	217,000		0
Dollar Value of Shares Repurchased	17		0
Remaining dollar value of shares that may be repurchased	$ 983

[1] Includes the effect of $26 million in share repurchases (0.3 million shares) with trade dates prior to March 21, 2015 but cash settlement dates subsequent to March 21, 2015.