Quarterly report pursuant to Section 13 or 15(d)

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

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Derivative Instrument and Hedging Transactions (Hedging of Precious Metals Inventory) (Details) - USD ($)
$ in Thousands
Mar. 31, 2017
Jun. 30, 2016
Derivatives, Fair Value [Line Items]    
Inventory $ 345,531 $ 245,057
Commemorative coin inventory, held at lower of cost or market (41) (16)
Premium on metals position (4,747) (4,627)
Inventory value not hedged (4,788) (4,643)
Subtotal 340,743 240,414
Commitments at market:    
Open inventory purchase commitments 629,212 550,810
Open inventory sales commitments (158,554) (237,325)
Margin sale commitments (9,084) (12,439)
In-transit inventory no longer subject to market risk (2,819) (7,363)
Unhedgable premiums on open commitment positions 203 400
Inventory borrowed from suppliers (6,437) (4,352)
Product financing arrangements (156,450) (59,358)
Advances on industrial metals 2,231 4,521
Inventory subject to price risk 639,045 475,308
Inventory subject to derivative financial instruments:    
Market value of derivative financial instruments 637,373 474,979
Net inventory subject to commodity price risk 1,672 329
Precious metals forward contracts at market values    
Inventory subject to derivative financial instruments:    
Market value of derivative financial instruments 391,967 188,530
Precious metals futures contracts at market values    
Inventory subject to derivative financial instruments:    
Market value of derivative financial instruments $ 245,406 $ 286,449