Inventories, Including Long-Term Mill and Leach Stockpiles (Unaudited) (Tables)

9 Months Ended

Sep. 30, 2018

Inventory Disclosure [Abstract]

Schedule of Inventory

The components of inventories follow (in millions):

	September 30, 2018		December 31, 2017
Current inventories:
Total materials and supplies, neta	$	1,439	$	1,305
Mill stockpiles	$	287	$	360
Leach stockpiles	1,152		1,062
Total current mill and leach stockpiles	$	1,439	$	1,422
Raw materials (primarily concentrate)	$	299	$	265
Work-in-process	174		154
Finished goods	696		747
Total product inventories	$	1,169	$	1,166
Long-term inventories:
Mill stockpiles	$	285	$	300
Leach stockpiles	1,070		1,109
Total long-term mill and leach stockpiles	$	1,355	$	1,409

a. Materials and supplies inventory was net of obsolescence reserves totaling $25 million at September 30, 2018, and $29 million at December 31, 2017.