Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ (11,436)	$ 17,796
Embedded Derivative Financial Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(4,019)	23,534
Palmarejo royalty obligation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(6,218)	(9,105)
Rochester Royalty Obligation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(673)	0
Gold Put Purchase and Call Sold Options Net [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(1,494)	4,227
Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ 968	$ (860)