Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ (8,282)	$ 66,754	$ (19,717)	$ 84,550
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	(5,061)	61,066	(15,296)	75,495
Rochester Royalty Obligation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(1,837)	0	(2,510)	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	(1,374)	6,350	(2,868)	10,577
Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(10)	(662)	957	(1,522)
Operating Segments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ (8,282)	$ 66,754