Fair Value Measurements (Details 1) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Assets:
Total assets	$ 62,524	$ 14,656
Liabilities:
Total liabilities	66,886	63,558
Royalty obligation embedded derivative [Member]
Liabilities:
Derivative fair value of derivative liability	44,357	40,338
Royalty Obligation [Member]
Liabilities:
Derivative fair value of derivative liability	22,303
Rochester Royalty Obligation [Member]
Liabilities:
Derivative fair value of derivative liability		21,630
Other Derivative Instrument [Member]
Assets:
Fair value of derivative asset	258
Liabilities:
Derivative fair value of derivative liability		1,590
Gold Put Purchase and Call Sold Options Net [Member]
Assets:
Fair value of derivative asset	992
Liabilities:
Derivative fair value of derivative liability	226
Short-term Deposit [Member]
Assets:
Short-term Deposits	45,628	14,521
Marketable securities [Member]
Assets:
Restricted certificates of deposits	15,646	135
Fair Value, Inputs, Level 1 [Member]
Assets:
Total assets	61,274	14,521
Liabilities:
Total liabilities	0	0
Fair Value, Inputs, Level 1 [Member] | Royalty obligation embedded derivative [Member]
Liabilities:
Derivative fair value of derivative liability	0	0
Fair Value, Inputs, Level 1 [Member] | Royalty Obligation [Member]
Liabilities:
Derivative fair value of derivative liability	0
Fair Value, Inputs, Level 1 [Member] | Rochester Royalty Obligation [Member]
Liabilities:
Derivative fair value of derivative liability		0
Fair Value, Inputs, Level 1 [Member] | Other Derivative Instrument [Member]
Assets:
Fair value of derivative asset	0
Liabilities:
Derivative fair value of derivative liability		0
Fair Value, Inputs, Level 1 [Member] | Gold Put Purchase and Call Sold Options Net [Member]
Assets:
Fair value of derivative asset	0
Liabilities:
Derivative fair value of derivative liability	0
Fair Value, Inputs, Level 1 [Member] | Short-term Deposit [Member]
Assets:
Short-term Deposits	45,628	14,521
Fair Value, Inputs, Level 1 [Member] | Marketable securities [Member]
Assets:
Restricted certificates of deposits	15,646	0
Fair Value, Inputs, Level 2 [Member]
Assets:
Total assets	1,250	135
Liabilities:
Total liabilities	226	1,590
Fair Value, Inputs, Level 2 [Member] | Royalty obligation embedded derivative [Member]
Liabilities:
Derivative fair value of derivative liability	0	0
Fair Value, Inputs, Level 2 [Member] | Royalty Obligation [Member]
Liabilities:
Derivative fair value of derivative liability	0
Fair Value, Inputs, Level 2 [Member] | Rochester Royalty Obligation [Member]
Liabilities:
Derivative fair value of derivative liability		0
Fair Value, Inputs, Level 2 [Member] | Other Derivative Instrument [Member]
Assets:
Fair value of derivative asset	258
Liabilities:
Derivative fair value of derivative liability		1,590
Fair Value, Inputs, Level 2 [Member] | Gold Put Purchase and Call Sold Options Net [Member]
Liabilities:
Derivative fair value of derivative liability	226
Fair Value, Inputs, Level 2 [Member] | Short-term Deposit [Member]
Assets:
Short-term Deposits	0	0
Fair Value, Inputs, Level 2 [Member] | Marketable securities [Member]
Assets:
Restricted certificates of deposits	0	135
Fair Value, Inputs, Level 3 [Member]
Assets:
Total assets	0	0
Liabilities:
Total liabilities	66,660	61,968
Fair Value, Inputs, Level 3 [Member] | Royalty obligation embedded derivative [Member]
Liabilities:
Derivative fair value of derivative liability	44,357	40,338
Fair Value, Inputs, Level 3 [Member] | Royalty Obligation [Member]
Liabilities:
Derivative fair value of derivative liability	22,303
Fair Value, Inputs, Level 3 [Member] | Rochester Royalty Obligation [Member]
Liabilities:
Derivative fair value of derivative liability		21,630
Fair Value, Inputs, Level 3 [Member] | Other Derivative Instrument [Member]
Assets:
Fair value of derivative asset	0
Liabilities:
Derivative fair value of derivative liability		0
Fair Value, Inputs, Level 3 [Member] | Gold Put Purchase and Call Sold Options Net [Member]
Assets:
Fair value of derivative asset	0
Liabilities:
Derivative fair value of derivative liability	0
Fair Value, Inputs, Level 3 [Member] | Short-term Deposit [Member]
Assets:
Short-term Deposits	0	0
Fair Value, Inputs, Level 3 [Member] | Marketable securities [Member]
Assets:
Restricted certificates of deposits	$ 0	$ 0