Shareholders' Equity (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 19, 2016	Mar. 21, 2015
Repurchase Of Shares Of Common Stock [Line Items]
Value of share repurchases with trade dates prior to current reporting date but with settlement dates subsequent to the current reporting date.		$ 26
Shares Repurchased	13,275	1,996
Dollar Value of Shares Repurchased	$ 925	$ 150	[1]
Remaining Dollar Value of Shares that may be Repurchased	$ 8
Number of shares repurchased with trade dates prior to current reporting date but with settlement dates subsequent to the current reporting date.		300
November 2013 [Member]
Repurchase Of Shares Of Common Stock [Line Items]
Shares Repurchased	0	1,779
Dollar Value of Shares Repurchased	$ 0	$ 133
Remaining Dollar Value of Shares that may be Repurchased	$ 0
November 2014 [Member]
Repurchase Of Shares Of Common Stock [Line Items]
Shares Repurchased	0	217
Dollar Value of Shares Repurchased	$ 0	$ 17
Remaining Dollar Value of Shares that may be Repurchased	$ 0
December 2015 [Member]
Repurchase Of Shares Of Common Stock [Line Items]
Shares Repurchased	13,275	0
Dollar Value of Shares Repurchased	$ 925	$ 0
Remaining Dollar Value of Shares that may be Repurchased	8
December 2016 [Member]
Repurchase Of Shares Of Common Stock [Line Items]
Remaining Dollar Value of Shares that may be Repurchased	$ 500

[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.