Summary of Significant Accounting Policies (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 27, 2014	Dec. 28, 2013		Dec. 29, 2012
Repurchase Of Shares Of Common Stock [Abstract]
Stock Repurchased During Period, Value	$ (820)	$ (750)	[1]	$ (985)
Reduction to Retained earnings
Repurchase Of Shares Of Common Stock [Abstract]
Stock Repurchased During Period, Value	$ (725)	$ (640)		$ (794)

[1] 2013 amount excludes and 2012 amount includes the effect of $20 million in share repurchases (0.3 million shares) with trade dates prior to the 2012 fiscal year end but with settlement dates subsequent to the 2012 fiscal year end.