Income Taxes (Details 4) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Deferred Tax Assets (Table Amounts)
Retiree benefits	$ 2,814	$ 2,549
Accrued employee compensation	349	316
Provisions for accrued liabilities	295	347
Inventory	287	227
Stock-based compensation	72	76
Other	72	68
Gross deferred tax assets	3,889	3,583
Less valuation allowance	(31)	(34)
Net deferred tax assets	3,858	3,549
Deferred Tax Liabilities (Table Amounts)
Goodwill	798	788
Property, plant and equipment, net	321	297
Contract accounting differences	1,200	976
Other	77	79
Gross deferred tax liabilities	2,396	2,140
Total net deferred tax assets	$ 1,462	$ 1,409