XML 16 R37.htm IDEA: XBRL DOCUMENT v2.4.0.6
MINERAL PROPERTY INTERESTS AND ASSET RETIREMENT OBLIGATIONS (Details) (USD $)
 3 Months Ended 6 Months Ended 12 Months Ended 6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Jun. 30, 2012
Jun. 30, 2011
Dec. 31, 2011
Jun. 30, 2012
Tonkin Complex
Jun. 30, 2012
Gold Bar Complex
Jun. 30, 2012
Limo Complex
Jun. 30, 2012
Battle Mountain Complex
Jun. 30, 2012
Other United States Properties
Jun. 30, 2012
Los Azules Copper Project
Jun. 30, 2012
Other Argentina exploration properties in San Juan, Argentina
Jun. 30, 2012
Cerro Negro Region
Jun. 30, 2012
Other Argentina exploration properties in Santa Cruz, Argentina
Jun. 30, 2012
Other Argentina exploration properties in Catamarca, Argentina
Jun. 30, 2012
Other Argentina exploration properties in Chubut, Argentina
Jun. 30, 2012
El Gallo Complex
Jun. 30, 2012
Other Mexico Exploration Properties in Sinaloa, Mexico
Jun. 30, 2012
Tonkin property and Magistral mine portion of the El Gallo Complex
item
Jun. 30, 2012
Minera Andes
Jan. 24, 2012
Minera Andes
MINERAL PROPERTY INTERESTS                                          
Mineral property interests                                         $ 597,374,000
Total 843,764,000   843,764,000   245,454,000 52,430,000 77,012,000 50,098,000 31,106,000 22,009,000 486,862,000 7,819,000 80,889,000 19,194,000 2,362,000 248,000 9,469,000 4,266,000      
Increase in mineral property interests since acquisition     598,300,000                                 597,400,000  
Number of most significant properties subject to reclamation obligations                                     2    
Undiscounted estimated reclamation costs           3,800,000                     4,600,000        
Cash bonding for mineral properties in the United States 5,190,000   5,190,000   5,190,000                                
Changes in the asset retirement obligations                                          
Asset retirement obligation liability - opening balance     6,253,000 6,153,000 6,153,000                                
Settlements     (14,000)   (82,000)                                
Accretion of liability 120,000 137,000 232,000 266,000 524,000                                
Adjustment reflecting updated estimates     147,000   (342,000)                                
Asset retirement obligation liability - ending balance 6,618,000   6,618,000   6,253,000                                
Current portion of the asset retirement obligation $ 510,000   $ 510,000   $ 512,000