Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Assets:
Marketable securities	$ 19,844	$ 0
Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents	44,708	11
Short-term investments	20,254
Marketable securities	19,844
Restricted certificates of deposits	548	2,965
Total assets	89,208	12,083
Liabilities:
Total liabilities	184,304	184,367
Fair Value, Measurements, Recurring [Member] | Gold forward contracts [Member]
Assets:
Derivative Asset, Fair Value		425
Fair Value, Measurements, Recurring [Member] | Gold lease facility [Member]
Liabilities:
Derivative Liability, Fair Value		2,213
Fair Value, Measurements, Recurring [Member] | Royalty obligation embedded derivative [Member]
Liabilities:
Derivative Liability, Fair Value	159,400	162,003
Fair Value, Measurements, Recurring [Member] | Put and call options [Member]
Assets:
Derivative Asset, Fair Value	3,040	5,403
Liabilities:
Derivative Liability, Fair Value	20,892	20,151
Fair Value, Measurements, Recurring [Member] | Silver ounces receivable from Mandalay [Member]
Assets:
Derivative Asset, Fair Value	814	1,594
Fair Value, Measurements, Recurring [Member] | Other derivative instrument, net [Member]
Assets:
Derivative Asset, Fair Value		1,685
Liabilities:
Other derivative instruments, net	4,012
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents	44,708	11
Short-term investments	20,254
Marketable securities	19,844
Restricted certificates of deposits	548	2,965
Total assets	91,274	8,804
Liabilities:
Total liabilities	20,892	20,151
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Gold forward contracts [Member]
Assets:
Derivative Asset, Fair Value		425
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Gold lease facility [Member]
Liabilities:
Derivative Liability, Fair Value		0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Royalty obligation embedded derivative [Member]
Liabilities:
Derivative Liability, Fair Value	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Put and call options [Member]
Assets:
Derivative Asset, Fair Value	5,920	5,403
Liabilities:
Derivative Liability, Fair Value	20,892	20,151
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Silver ounces receivable from Mandalay [Member]
Assets:
Derivative Asset, Fair Value	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Other derivative instrument, net [Member]
Assets:
Derivative Asset, Fair Value		0
Liabilities:
Other derivative instruments, net	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents	0	0
Short-term investments	0
Marketable securities	0
Restricted certificates of deposits	0	0
Total assets	814	3,279
Liabilities:
Total liabilities	163,412	164,216
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Gold forward contracts [Member]
Assets:
Derivative Asset, Fair Value		0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Gold lease facility [Member]
Liabilities:
Derivative Liability, Fair Value		2,213
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Royalty obligation embedded derivative [Member]
Liabilities:
Derivative Liability, Fair Value	159,400	162,003
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Put and call options [Member]
Assets:
Derivative Asset, Fair Value	0	0
Liabilities:
Derivative Liability, Fair Value	0	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Silver ounces receivable from Mandalay [Member]
Assets:
Derivative Asset, Fair Value	814	1,594
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Other derivative instrument, net [Member]
Assets:
Derivative Asset, Fair Value		1,685
Liabilities:
Other derivative instruments, net	4,012
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents	0	0
Short-term investments	0
Marketable securities	0
Restricted certificates of deposits	0	0
Total assets	0	0
Liabilities:
Total liabilities	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Gold forward contracts [Member]
Assets:
Derivative Asset, Fair Value		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Gold lease facility [Member]
Liabilities:
Derivative Liability, Fair Value		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Royalty obligation embedded derivative [Member]
Liabilities:
Derivative Liability, Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Put and call options [Member]
Assets:
Derivative Asset, Fair Value	0	0
Liabilities:
Derivative Liability, Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Silver ounces receivable from Mandalay [Member]
Assets:
Derivative Asset, Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Other derivative instrument, net [Member]
Assets:
Derivative Asset, Fair Value		0
Liabilities:
Other derivative instruments, net	$ 0