Inventories

3 Months Ended

Mar. 31, 2018

Inventory Disclosure [Abstract]

Inventories

Inventories

	March 31, 2018		December 31, 2017
Finished goods	$	718	$	669
Work-in-process	1,406		1,349
Purchased raw materials	435		381
Operating supplies	89		81
Total inventories	$	2,648	$	2,480

At March 31, 2018 and December 31, 2017, the portion of inventories valued on a last-in, first-out (LIFO) basis was $1,302 and $1,208, respectively. If valued on an average-cost basis, total inventories would have been $495 and $481 higher at March 31, 2018 and December 31, 2017, respectively.