Income Taxes (Details 4) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred Tax Assets (Table Amounts)
Retirement benefits	$ 2,710	$ 1,819
Provisions for accrued liabilities	675	649
Stock-based compensation	146	130
Other	151	147
Gross deferred tax assets	3,682	2,745
Less valuation allowance	(52)	(50)
Net deferred tax assets	3,630	2,695
Deferred Tax Liabilities (Table Amounts)
Goodwill	804	716
Property, plant, and equipment, net	376	277
Contract accounting differences	199	218
Other	135	88
Gross deferred tax liabilities	1,514	1,299
Total net deferred tax assets	$ 2,116	$ 1,396