Inventories (Tables)
 6 Months Ended
Jun. 30, 2017
Inventory Disclosure [Abstract]  
Inventories
($ in millions)
June 30, 2017
 
December 31, 2016
Finished products
$
1,114

 
$
947

Work in process
186

 
165

Raw materials
433

 
370

Supplies
33

 
32

Total Inventories
$
1,766

 
$
1,514