Supplemental Cash Flow Information - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2012
Supplemental Cash Flow Information Activities [Line Items]
Non-cash increase to Investments	$ 6	$ 129
La Herradura [Member]
Supplemental Cash Flow Information Activities [Line Items]
Non-cash settlement	27
McCoy Cove [Member]
Supplemental Cash Flow Information Activities [Line Items]
Mineral interests received	$ 2
Regis Resources Ltd. [Member]
Supplemental Cash Flow Information Activities [Line Items]
Non-core assets in exchange for shares		23