Inventory (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Inventory Disclosure [Abstract]
Raw materials	$ 1,117	$ 955
Work-in-process	324	428
Finished goods	1,180	1,115
Inventory at FIFO	2,621	2,498
Excess of FIFO over LIFO cost	(123)	(116)
Total inventory	$ 2,498	$ 2,382