Quarterly report pursuant to Section 13 or 15(d)

Hedging Transactions (Outstanding Commitments) (Details)

v2.4.1.9
Hedging Transactions (Outstanding Commitments) (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Jun. 30, 2014
Derivative [Line Items]    
Purchase commitments $ 414,750amrk_OpenInventoryPurchaseCommitments $ 489,944amrk_OpenInventoryPurchaseCommitments
Sale commitments (188,630)amrk_OpenInventorySaleCommitments (190,108)amrk_OpenInventorySaleCommitments
Margin sales commitments (10,870)amrk_MarginSaleCommitments (15,751)amrk_MarginSaleCommitments
Open derivative contracts 330,094invest_DerivativeNotionalAmount 427,039invest_DerivativeNotionalAmount
Precious metals forward contracts at market values    
Derivative [Line Items]    
Open derivative contracts 209,387invest_DerivativeNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForwardContractsMember 		206,055invest_DerivativeNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForwardContractsMember
Future contracts    
Derivative [Line Items]    
Open derivative contracts $ 120,707invest_DerivativeNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember 		$ 220,984invest_DerivativeNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember