Shareholders' Equity (Details) - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2016		Dec. 26, 2015	Dec. 27, 2014
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.	$ 45
Number of shares repurchased with trade dates prior to current reporting date but with settlement dates subsequent to the current reporting date.	700
Stock Repurchased During Period, Shares	67,963	[1]	15,942	11,225
Stock Repurchased During Period, Value	$ 5,447	[1]	$ 1,200	$ 820
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 1,900
November 2016 [Member]
Repurchase Of Shares Of Common Stock [Line Items]
Stock Repurchased During Period, Shares	1,337		0	0
Stock Repurchased During Period, Value	$ 85		$ 0	$ 0
December 2015 [Member]
Repurchase Of Shares Of Common Stock [Line Items]
Stock Repurchased During Period, Shares	13,368		932	0
Stock Repurchased During Period, Value	$ 933		$ 67	$ 0
May 2016 [Member]
Repurchase Of Shares Of Common Stock [Line Items]
Stock Repurchased During Period, Shares	50,435		0	0
Stock Repurchased During Period, Value	$ 4,200		$ 0	$ 0
March 2016 [Member]
Repurchase Of Shares Of Common Stock [Line Items]
Stock Repurchased During Period, Shares	2,823		0	0
Stock Repurchased During Period, Value	$ 229		$ 0	$ 0
November 2014 [Member]
Repurchase Of Shares Of Common Stock [Line Items]
Stock Repurchased During Period, Shares	0		13,231	0
Stock Repurchased During Period, Value	$ 0		$ 1,000	$ 0
November 2013 [Member]
Repurchase Of Shares Of Common Stock [Line Items]
Stock Repurchased During Period, Shares	0		1,779	8,488
Stock Repurchased During Period, Value	$ 0		$ 133	$ 617
November 2012 [Member]
Repurchase Of Shares Of Common Stock [Line Items]
Stock Repurchased During Period, Shares	0		0	2,737
Stock Repurchased During Period, Value	$ 0		$ 0	$ 203
November 2016 [Member]
Repurchase Of Shares Of Common Stock [Line Items]
Stock Repurchase Program, Authorized Amount	$ 2,000

[1] Includes the effect of $45 million in share repurchases (0.7 million shares) with trade dates prior to December 31, 2016 but settlement dates subsequent to December 31, 2016.