Financial Instruments (Cash and Cash Equivalents and Fair Value Measurements) (Details) - USD ($)	Jun. 25, 2016	Dec. 26, 2015
Schedule of Investments [Line Items]
Cash and cash equivalents	$ 957,000,000	$ 785,000,000
Fair value, level 1 to level 2 transfers, amount	0	0
Fair value, level 2 to level 1 transfers, amount	0	0
Level 2
Schedule of Investments [Line Items]
Cash and cash equivalents	550,000,000	376,000,000
Cash
Schedule of Investments [Line Items]
Cash and cash equivalents	407,000,000	409,000,000
Commercial Paper | Level 2
Schedule of Investments [Line Items]
Cash and cash equivalents	$ 550,000,000	$ 376,000,000