Annual report pursuant to Section 13 and 15(d)

Financing Agreements (Details)

v3.7.0.1
Financing Agreements (Details) - USD ($)
 12 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Mar. 31, 2016
Schedule Of Financing Arrangements [Line Items]      
Liability on borrowed metals $ 5,625,000 $ 4,352,000  
Product financing obligation 135,343,000 59,358,000  
Line of Credit | Trading credit facility      
Schedule Of Financing Arrangements [Line Items]      
Interest expense, notes payable $ 6,400,000 $ 4,900,000  
Percentage of total expense recognized 63.60% 77.90%  
Effective rate of interest 3.18% 2.83%  
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    
Line of credit, current borrowing capacity     $ 225,000,000
Line of credit, accordion option     $ 50,000,000
Payments of financing costs 1,200,000    
Accumulated amortization of loan cost $ 100,000 $ 600,000  
Variable rate basis one-month LIBOR    
Credit facility, interest rate at period end 1.17% 0.47%  
Borrowings due on demand $ 180,000,000 $ 212,000,000  
Credit facility, remaining borrowing capacity 45,600,000 $ 17,800,000  
Credit facility, minimum required tangible net worth $ 38,900,000    
Debt Instrument, Covenant, Maximum Dividend Payment, Percentage 35.00%    
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%