Pension and Other Postretirement Benefits - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 26, 2015	Jun. 27, 2014	Jun. 26, 2015	Jun. 27, 2014
Pension Plans [Member]
Components of net periodic benefit cost:
Service cost	$ 32	$ 27	$ 64	$ 54
Interest cost	37	37	74	73
Expected return on plan assets	$ (52)	$ (49)	(104)	(97)
Amortization of prior service costs (credits)			1	1
Amortization of net loss (gain)	$ 17	$ 5	$ 34	9
Curtailment loss				1
Net periodic benefit cost	$ 34	$ 20	$ 69	41
Postretirement Benefit Plans [Member]
Components of net periodic benefit cost:
Service cost	1	1	2	2
Interest cost	2	2	4	4
Expected return on plan assets	(1)	$ (1)	(2)	(2)
Amortization of prior service costs (credits)	$ (1)		$ (2)	(1)
Amortization of net loss (gain)		$ (1)		$ (1)
Curtailment loss
Net periodic benefit cost	$ 1	$ 1	$ 2	$ 2