Inventories

12 Months Ended

Dec. 31, 2017

Inventory Disclosure [Abstract]

Inventories

Inventories

December 31,	2017		2016
Finished goods	$	669	$	625
Work-in-process	1,349		1,144
Purchased raw materials	381		408
Operating supplies	81		76
	$	2,480	$	2,253

At December 31, 2017 and 2016, the total amount of inventories valued on a LIFO basis was $1,208 and $947, respectively. If valued on an average-cost basis, total inventories would have been $481 and $371 higher at December 31, 2017 and 2016, respectively. During 2017 and 2016, reductions in LIFO inventory quantities caused partial liquidations of the lower cost LIFO inventory base. These liquidations resulted in the recognition of immaterial income amounts in 2017, 2016, and 2015.