Pretax Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 26, 2016	Jun. 28, 2015	Jun. 26, 2016	Jun. 28, 2015
Qualified defined benefit pension plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 212	$ 218	$ 424	$ 435
Interest cost	466	447	931	895
Expected return on plan assets	(666)	(683)	(1,333)	(1,367)
Recognized net actuarial losses	339	400	679	800
Amortization of prior service (credits) costs	(97)	(98)	(193)	(195)
Total net periodic benefit cost	254	284	508	568
Retiree medical and life insurance plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	6	5	12	10
Interest cost	29	27	59	55
Expected return on plan assets	(35)	(37)	(69)	(74)
Recognized net actuarial losses	9	11	17	22
Amortization of prior service (credits) costs	6	1	11	2
Total net periodic benefit cost	$ 15	$ 7	$ 30	$ 15