Inventories (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Inventories [Abstract]
Raw materials	$ 153	$ 159
Work-in-process	786	827
Finished goods, including parts and subassemblies	2,226	2,150
Other	23	24
Total gross inventories	3,188	3,160
Excess of current standard costs over LIFO costs	(73)	(86)
Allowances	(177)	(145)
Total net inventories	$ 2,938	$ 2,929