Inventories (Tables)
 9 Months Ended
Sep. 30, 2017
Inventory Disclosure [Abstract]  
Inventories
Inventories consisted of the following:
Millions of dollars
September 30,
2017
December 31,
2016
Finished products and parts
$
1,565

$
1,388

Raw materials and supplies
720

778

Work in process
159

109

Total
$
2,444

$
2,275