Inventories, Including Long-Term Mill and Leach Stockpiles (Unaudited) (Details) - USD ($) $ in Millions		3 Months Ended	6 Months Ended
		Jun. 30, 2015	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Components of Inventories [Line Items]
Raw materials (primarily concentrates)		$ 306	$ 306		$ 288
Work-in-process		155	155		174
Finished goods		1,023	1,023		1,099
Total product inventories		1,484	1,484		1,561
Total mill and leach stockpiles		1,933	1,933		1,914
Total materials and supplies, net	[1]	2,014	2,014		1,886
Total long-term mill and leach stockpiles		2,277	2,277		2,179
Inventory obsolescence reserves		25	25		20
Lower of cost or market inventory adjustments		(59)	(63)	$ 0
Current [Member]
Components of Inventories [Line Items]
Mill stockpiles		130	130		86
Leach stockpiles		1,803	1,803		1,828
Total mill and leach stockpiles		1,933	1,933		1,914
Long-Term [Member]
Components of Inventories [Line Items]
Mill stockpiles		361	361		360
Leach stockpiles		1,916	1,916		1,819
Total long-term mill and leach stockpiles	[2]	2,277	2,277		$ 2,179
Molybdenum [Member]
Components of Inventories [Line Items]
Lower of cost or market inventory adjustments		(48)	(52)
Copper [Member]
Components of Inventories [Line Items]
Lower of cost or market inventory adjustments		$ (11)	$ (11)

[1] Materials and supplies inventory was net of obsolescence reserves totaling $25 million at June 30, 2015, and $20 million at December 31, 2014.

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