Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 26, 2015	Jun. 27, 2014	Jun. 26, 2015	Jun. 27, 2014
Statement of Comprehensive Income [Abstract]
Net of income taxes on unrealized gains on hedging instruments	$ 2	$ 3	$ 1	$ 1
Income tax effect on amortization of net loss and prior service cost previously recognized	5	$ 2	11	$ 3
Income tax expense on net gain arising during the period	$ 5		$ 5