Consolidated Statements of Operations and Comprehensive Loss (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended		12 Months Ended				172 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2013
Operating income and (expenses):
Exploration and evaluation	$ (12,939)	$ (10,363)	$ (14,126)	$ (18,314)	$ (15,168)	$ (8,512)	$ (55,205)
Corporate administration	(4,158)	(7,791)	(6,616)	(11,914)	(16,109)	(9,471)	(42,202)
Depreciation	(90)	(42)	(197)	(170)	(123)	(38)	(459)
Write-down of mineral property		(931)		(943)	(1,874)		(2,924)
Total operating expenses	(17,187)	(19,127)	(20,939)	(31,341)	(33,274)	(18,021)	(100,790)
Non-operating income and (expenses):
Interest income	301	538	232	627	864	632	2,208
Gain/(loss) on currency translation	1,457	(2,686)	(1,531)	1,525	(2,618)	3,077	99
Loss on sale of marketable securities	(7)	(9)	(39)	(9)	(11)		(57)
Gain/(loss) on derivatives	(4)	173	81	(142)	35	(2,345)	(871)
Other income/(expense)	10	50	(50)	(22)	10		(30)
Total non-operating income/(expenses)	1,757	(1,934)	(1,307)	1,979	(1,720)	1,364	1,349
Net loss	(15,430)	(21,061)	(22,246)	(29,362)	(34,994)	(16,657)	(99,441)
Other comprehensive income/(loss)
Realized loss on available-for-sale securities	7	9	39	9	11		57
Unrealized gain/(loss) on available-for-sale securities	2	(39)	4	(17)	(59)	3	(57)
Total other comprehensive income/(loss)	9	(30)	43	(8)	(48)	3
COMPREHENSIVE LOSS	$ (15,421)	$ (21,091)	$ (22,203)	$ (29,370)	$ (35,042)	$ (16,654)	$ (99,441)
LOSS PER SHARE - BASIC AND DILUTED	$ (0.35)	$ (0.48)	$ (0.48)	$ (0.66)	$ (0.79)	$ (0.43)
WEIGHTED AVERAGE NUMBER OF SHARES OUTSTANDING	44,610,070	44,096,346	46,299,560	44,581,287	44,189,656	38,585,541