Segment Reporting - Consolidated Revenues by Geographic Area (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	$ 40,122	$ 39,807	$ 39,498
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	17,424	18,478	17,519
Europe, Middle East and Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	11,478	10,953	10,677
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	4,337	3,918	3,825
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	3,122	2,846	2,673
Latin America
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	2,339	2,155	2,825
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	$ 1,422	$ 1,457	$ 1,979