Acquisitions (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands			3 Months Ended		6 Months Ended
	Apr. 17, 2015	Feb. 20, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Business Acquisition [Line Items]
Stock Issued During Period, Shares, Acquisitions					32,667
Business Acquisition, Pro Forma Information [Abstract]
Stock Issued During Period, Value, Acquisitions					$ 5.78
Paramount Gold and Silver Corp. [Member]
Business Acquisition [Line Items]
Common shares issued	$ 188,817
Cash	8,530
Transaction advisory fees and other acquisition costs	3,898
Total purchase price	201,245
Liabilities assumed:
Accounts payable and accrued liabilities	2,737
Deferred income taxes	103,089
Total liabilities assumed	105,826
Total consideration	307,071
Assets acquired:
Cash	118
Receivables and other current assets	1,685
Property, plant, and equipment	215
Mining properties, net	305,053
Total assets acquired	$ 307,071
Wharf Gold Mine [Member]
Business Acquisition [Line Items]
Cash		$ 99,840
Transaction advisory fees and other acquisition costs			$ 2,100		$ 2,100
Liabilities assumed:
Accounts payable and accrued liabilities		5,494
Reclamation		18,270
Deferred income taxes		9,680
Other non-current liabilities		3,750
Total liabilities assumed		37,194
Total consideration		137,034
Assets acquired:
Cash		982
Receivables and other current assets		3,061
Inventory		2,147
Ore on leach pads		12,710
Other current assets		2,924
Property, plant, and equipment		30,055
Mining properties, net		81,189
Other non-current assets		3,966
Total assets acquired		$ 137,034
Business Acquisition, Pro Forma Information [Abstract]
Revenue			166,263	$ 186,104	337,219	$ 365,021
Income (loss) before income and mining taxes			(16,937)	(33,391)	(50,209)	(70,065)
Net income (loss)			$ (16,677)	$ (35,980)	$ (50,017)	$ (67,937)