Quarterly report pursuant to Section 13 or 15(d)

Assets and Liabilities, at Fair Value (Assets and Liabilities Measured at Fair Value on Recurring Basis) (Details)

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Assets and Liabilities, at Fair Value (Assets and Liabilities Measured at Fair Value on Recurring Basis) (Details) - USD ($)
$ in Thousands
Dec. 31, 2016
Jun. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets - future and forward contracts $ 33,759 $ 38,763
Derivative liabilities 74,358 36,454
Fair Value on a Recurring Basis    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Inventory 290,889 245,041
Total assets valued at fair value 330,466 278,773
Liability on borrowed metals 3,471 4,352
Product financing arrangement 121,466 59,358
Total liabilities, valued at fair value 199,295 100,164
Fair Value on a Recurring Basis | Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Inventory 290,889 245,041
Total assets valued at fair value 330,466 278,773
Liability on borrowed metals 3,471 4,352
Product financing arrangement 121,466 59,358
Total liabilities, valued at fair value 199,295 100,164
Fair Value on a Recurring Basis | Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Inventory 0 0
Total assets valued at fair value 0 0
Liability on borrowed metals 0 0
Product financing arrangement 0 0
Total liabilities, valued at fair value 0 0
Fair Value on a Recurring Basis | Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Inventory 0 0
Total assets valued at fair value 0 0
Liability on borrowed metals 0 0
Product financing arrangement 0 0
Total liabilities, valued at fair value 0 0
Liability on margin accounts | Fair Value on a Recurring Basis    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative liabilities 5,415 8,182
Liability on margin accounts | Fair Value on a Recurring Basis | Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative liabilities 5,415 8,182
Liability on margin accounts | Fair Value on a Recurring Basis | Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative liabilities 0 0
Liability on margin accounts | Fair Value on a Recurring Basis | Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative liabilities 0 0
Open sale and purchase commitments | Fair Value on a Recurring Basis    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative liabilities 68,434 1,919
Open sale and purchase commitments | Fair Value on a Recurring Basis | Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative liabilities 68,434 1,919
Open sale and purchase commitments | Fair Value on a Recurring Basis | Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative liabilities 0 0
Open sale and purchase commitments | Fair Value on a Recurring Basis | Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative liabilities 0 0
Future contracts | Fair Value on a Recurring Basis    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative liabilities 470 13,914
Future contracts | Fair Value on a Recurring Basis | Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative liabilities 470 13,914
Future contracts | Fair Value on a Recurring Basis | Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative liabilities 0 0
Future contracts | Fair Value on a Recurring Basis | Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative liabilities 0 0
Forward contracts | Fair Value on a Recurring Basis    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative liabilities 39 12,439
Forward contracts | Fair Value on a Recurring Basis | Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative liabilities 39 12,439
Forward contracts | Fair Value on a Recurring Basis | Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative liabilities 0 0
Forward contracts | Fair Value on a Recurring Basis | Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative liabilities 0 0
Derivative Asset Open Purchases And Sales Commitments | Fair Value on a Recurring Basis    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets - future and forward contracts 3,184 32,347
Derivative Asset Open Purchases And Sales Commitments | Fair Value on a Recurring Basis | Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets - future and forward contracts 3,184 32,347
Derivative Asset Open Purchases And Sales Commitments | Fair Value on a Recurring Basis | Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets - future and forward contracts 0 0
Derivative Asset Open Purchases And Sales Commitments | Fair Value on a Recurring Basis | Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets - future and forward contracts 0 0
Future contracts | Fair Value on a Recurring Basis    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets - future and forward contracts 19,531  
Future contracts | Fair Value on a Recurring Basis | Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets - future and forward contracts 19,531  
Future contracts | Fair Value on a Recurring Basis | Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets - future and forward contracts 0  
Future contracts | Fair Value on a Recurring Basis | Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets - future and forward contracts 0  
Forward contracts | Fair Value on a Recurring Basis    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets - future and forward contracts 16,862 1,385
Forward contracts | Fair Value on a Recurring Basis | Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets - future and forward contracts 16,862 1,385
Forward contracts | Fair Value on a Recurring Basis | Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets - future and forward contracts 0 0
Forward contracts | Fair Value on a Recurring Basis | Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets - future and forward contracts $ 0 $ 0