Inventories, Including Long-Term Mill and Leach Stockpiles (Unaudited) (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
		Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Components of Inventories [Line Items]
Raw materials (primarily concentrates)		$ 281	$ 281		$ 288
Work-in-process		102	102		174
Finished goods		996	996		1,099
Total product inventories		1,379	1,379		1,561
Total mill and leach stockpiles		1,895	1,895		1,914
Total materials and supplies, net	[1]	2,071	2,071		1,886
Total long-term mill and leach stockpiles		2,326	2,326		2,179
Inventory obsolescence reserves		26	26		20
Lower of cost or market inventory adjustments		(91)	(154)	$ 0
Current [Member]
Components of Inventories [Line Items]
Mill stockpiles		118	118		86
Leach stockpiles		1,777	1,777		1,828
Total mill and leach stockpiles		1,895	1,895		1,914
Long-Term [Member]
Components of Inventories [Line Items]
Mill stockpiles		444	444		360
Leach stockpiles		1,882	1,882		1,819
Total long-term mill and leach stockpiles	[2]	2,326	2,326		$ 2,179
Molybdenum [Member]
Components of Inventories [Line Items]
Lower of cost or market inventory adjustments		(37)	(89)
Copper [Member]
Components of Inventories [Line Items]
Lower of cost or market inventory adjustments		$ (54)	$ (65)

[1] Materials and supplies inventory was net of obsolescence reserves totaling $26 million at September 30, 2015, and $20 million at December 31, 2014.

[2] Estimated metals in stockpiles not expected to be recovered within the next 12 months.