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

6 Months Ended

Jun. 30, 2017

Inventory Disclosure [Abstract]

Schedule of Inventory [Table Text Block]

The components of inventories follow (in millions):

	June 30, 2017		December 31, 2016
Current inventories:
Total materials and supplies, neta	$	1,264	$	1,306
Mill stockpiles	$	313	$	259
Leach stockpiles	1,046		1,079
Total current mill and leach stockpiles	$	1,359	$	1,338
Raw materials (primarily concentrate)	$	295	$	255
Work-in-process	121		114
Finished goods	603		629
Total product inventories	$	1,019	$	998
Long-term inventories:
Mill stockpiles	$	425	$	487
Leach stockpiles	1,129		1,146
Total long-term mill and leach stockpilesb	$	1,554	$	1,633

a. Materials and supplies inventory was net of obsolescence reserves totaling $30 million at June 30, 2017, and $29 million at December 31, 2016.

b. Estimated metals in stockpiles not expected to be recovered within the next 12 months.