Income Taxes - Components of Federal and Foreign Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets related to:
Accrued compensation and benefits	$ 584	$ 595
Pensions	2,623	2,495
Other postretirement benefit obligations	148	153
Contract accounting methods	539	531
Foreign company operating losses and credits	38	27
Other	160	154
Valuation allowance	(20)	(20)
Deferred tax assets, net	4,072	3,935
Deferred tax liabilities related to:
Goodwill and purchased intangibles	296	266
Property, plant and equipment	296	239
Exchanged debt securities and other	294	303
Deferred tax liabilities	886	808
Net deferred tax assets	$ 3,186	$ 3,127