Schedule of Net Periodic Benefit Costs (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Qualified defined benefit pension plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	$ 827	$ 836	$ 841
Interest cost	[1]	1,861	1,791	1,912
Expected return on plan assets	[1]	(2,666)	(2,734)	(2,693)
Recognized net actuarial losses	[1]	1,359	1,599	1,173
Amortization of net prior service (credit) cost	[1],[2]	(362)	(365)	(134)
Total net periodic benefit cost	[1],[3]	1,019	1,127	1,099
Retiree medical and life insurance plans
Defined Benefit Plan Disclosure [Line Items]
Service cost		24	21	22
Interest cost		119	110	123
Expected return on plan assets		(138)	(147)	(146)
Recognized net actuarial losses		34	43	23
Amortization of net prior service (credit) cost	[2]	22	4	4
Total net periodic benefit cost		$ 61	$ 31	$ 26

[1] Total net periodic benefit cost associated with our qualified defined benefit plans represents pension expense calculated in accordance with GAAP (FAS pension expense). We are required to calculate pension expense in accordance with both GAAP and CAS rules, each of which results in a different calculated amount of pension expense. The CAS pension cost is recovered through the pricing of our products and services on U.S. Government contracts and, therefore, is recognized in net sales and cost of sales for products and services. We include the difference between FAS pension expense and CAS pension cost, referred to as the FAS/CAS pension adjustment, as a component of other unallocated, net on our consolidated statements of earnings. The FAS/CAS pension adjustment, which was $902 million in 2016, $400 million in 2015, and $317 million in 2014, effectively adjusts the amount of CAS pension cost in the business segment operating profit so that pension expense recorded on our consolidated statements of earnings is equal to FAS pension expense. FAS pension expense and CAS pension costs reflect the reclassification for discontinued operations presentation of benefits related to former IS&GS salaried employees.

[2] Net of the reclassification for discontinued operations presentation of pension benefits related to former IS&GS salaried employees ($14 million in 2016, $24 million in 2015 and $17 million in 2014).

[3] FAS pension expense, CAS pension costs and severance charges reflect the reclassification for discontinued operations presentation of benefits related to former IS&GS salaried employees (see "Note 11 - Postretirement Plans").