Quarterly report pursuant to Section 13 or 15(d)

Financing Agreements (Details)

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Financing Agreements (Details) - USD ($)
 3 Months Ended 9 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Mar. 31, 2017
Mar. 31, 2016
Jun. 30, 2016
Schedule Of Financing Arrangements [Line Items]          
Liability on borrowed metals $ 6,437,000   $ 6,437,000   $ 4,352,000
Product financing obligation 156,450,000   156,450,000   59,358,000
Line of Credit | Trading credit facility          
Schedule Of Financing Arrangements [Line Items]          
Interest expense, notes payable $ 1,700,000 $ 1,300,000 $ 4,800,000 $ 3,600,000  
Percentage of total expense recognized 64.50% 76.70% 64.30% 84.40%  
Effective rate of interest 3.22% 2.82% 3.08% 2.79%  
Line of Credit | Trading credit facility | A-Mark | Trading credit facility          
Schedule Of Financing Arrangements [Line Items]          
Line of credit, maximum borrowing capacity $ 275,000,000   $ 275,000,000    
Line of credit, current borrowing capacity 225,000,000   225,000,000    
Line of credit, accordion option 50,000,000   50,000,000    
Payments of financing costs     900,000    
Accumulated amortization of loan cost $ 100,000   $ 100,000   $ 600,000
Variable rate basis     one-month LIBOR    
Credit facility, interest rate at period end 0.98%   0.98%   0.47%
Borrowings due on demand $ 213,000,000   $ 213,000,000   $ 212,000,000
Credit facility, remaining borrowing capacity $ 23,100,000   23,100,000   $ 17,800,000
Credit facility, minimum required tangible net worth     $ 38,900,000    
LIBOR | Line of Credit | Revolving Credit Facility          
Schedule Of Financing Arrangements [Line Items]          
Variable rate     2.50%    
LIBOR | Line of Credit | Bridge Loan          
Schedule Of Financing Arrangements [Line Items]          
Variable rate     4.50%