Pretax Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 25, 2016	Sep. 27, 2015	Sep. 25, 2016	Sep. 27, 2015
Qualified defined benefit pension plans
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 208	$ 207	$ 615	$ 623
Interest cost		465	448	1,396	1,343
Expected return on plan assets		(667)	(683)	(2,000)	(2,050)
Recognized net actuarial losses		340	399	1,019	1,199
Amortization of prior service (credits) costs		(90)	(91)	(272)	(274)
Total net periodic benefit cost	[1]	256	280	758	841
Retiree medical and life insurance plans
Defined Benefit Plan Disclosure [Line Items]
Service cost		6	6	18	16
Interest cost		30	28	89	83
Expected return on plan assets		(34)	(37)	(103)	(111)
Recognized net actuarial losses		8	10	25	32
Amortization of prior service (credits) costs		5	1	16	3
Total net periodic benefit cost		$ 15	$ 8	$ 45	$ 23

[1] FAS pension expense and CAS pension costs reflect the reclassification for discontinued operations presentation of benefits related to former IS&GS salaried employees (See Note 7).