Annual report pursuant to Section 13 and 15(d)

Derivative Instruments and Hedging Transactions (Hedging of Precious Metals Inventory) (Details)

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Derivative Instruments and Hedging Transactions (Hedging of Precious Metals Inventory) (Details) - USD ($)
$ in Thousands
Jun. 30, 2018
Jun. 30, 2017
Derivatives, Fair Value [Line Items]    
Inventory $ 280,116 $ 284,659
Precious metals held under financing arrangements 262,566 0
Inventory and precious metals held under financing arrangements 542,682 284,659
Commemorative coin inventory, held at lower of cost or market (99) (40)
Premium on metals position (3,530) (4,088)
Precious metal value not hedged (3,629) (4,128)
Subtotal 539,053 280,531
Commitments at market:    
Open inventory purchase commitments 342,287 587,687
Open inventory sales commitments (138,022) (121,602)
Margin sale commitments (5,988) (7,936)
In-transit inventory no longer subject to market risk (1,060) (3,931)
Unhedgeable premiums on open commitment positions 541 495
Borrowed precious metals (280,346) (5,625)
Product financing arrangements (113,940) (135,343)
Advances on industrial metals 6,044 1,580
Commitments at market (190,484) 315,325
Precious metal subject to price risk 348,569 595,856
Precious metal subject to derivative financial instruments:    
Market value of derivative financial instruments 347,415 595,681
Net precious metals subject to commodity price risk 1,154 175
Precious metals forward contracts at market values    
Precious metal subject to derivative financial instruments:    
Market value of derivative financial instruments 274,994 462,231
Precious metals futures contracts at market values    
Precious metal subject to derivative financial instruments:    
Market value of derivative financial instruments $ 72,421 $ 133,450