Quarterly report pursuant to Section 13 or 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
Dec. 31, 2018
Jun. 30, 2018
Derivatives, Fair Value [Line Items]    
Inventory $ 276,285 $ 280,116
Precious metals held under financing arrangements 226,905 262,566
Inventory and precious metals held under financing arrangements 503,190 542,682
Commemorative coin inventory, held at lower of cost or market (47) (99)
Premium on metals position (4,026) (3,530)
Precious metal value not hedged (4,073) (3,629)
Subtotal 499,117 539,053
Commitments at market:    
Open inventory purchase commitments 261,829 342,287
Open inventory sales commitments (180,204) (138,022)
Margin sale commitments (6,932) (5,988)
In-transit inventory no longer subject to market risk (1,340) (1,060)
Unhedgeable premiums on open commitment positions 3,442 541
Borrowed precious metals (227,317) (280,346)
Product financing arrangements (82,413) (113,940)
Advances on industrial metals 852 6,044
Commitments at market (232,083) (190,484)
Precious metal subject to price risk 267,034 348,569
Precious metal subject to derivative financial instruments:    
Market value of derivative financial instruments 265,760 347,415
Net precious metals subject to commodity price risk 1,274 1,154
Precious metals forward contracts at market values    
Precious metal subject to derivative financial instruments:    
Market value of derivative financial instruments 201,252 274,994
Precious metals futures contracts at market values    
Precious metal subject to derivative financial instruments:    
Market value of derivative financial instruments $ 64,508 $ 72,421