Quarterly report pursuant to Section 13 or 15(d)

Inventories (Details)

v2.4.1.9
Inventories (Details) (USD $)
 9 Months Ended 12 Months Ended
Mar. 31, 2015
Jun. 30, 2014
Inventory Disclosure [Abstract]    
Premium on metals position $ 3,668,000amrk_InventoryPurchasePremiumOnMetalsPositionmarkedtomarket $ 3,285,000amrk_InventoryPurchasePremiumOnMetalsPositionmarkedtomarket
Commemorative coin inventory, held at lower of cost or market 65,000amrk_InventoryCommemorativeCoinStatedAtLowerCostOrMarket 2,564,000amrk_InventoryCommemorativeCoinStatedAtLowerCostOrMarket
Unrealized gains (losses) included in inventory balance (100,000)amrk_InventoryUnrealizedGainsLossesResultingFromMarketValueAndCostOfPhysicalInventory 3,800,000amrk_InventoryUnrealizedGainsLossesResultingFromMarketValueAndCostOfPhysicalInventory
Borrowed metals 6,500,000amrk_BorrowedMetals 8,700,000amrk_BorrowedMetals
Product under financing arrangement 48,100,000amrk_ProductUnderFinancingArrangement 24,600,000amrk_ProductUnderFinancingArrangement
Inventories loaned under consignment 5,600,000us-gaap_OtherInventoryMaterialsSuppliesAndMerchandiseUnderConsignment 11,100,000us-gaap_OtherInventoryMaterialsSuppliesAndMerchandiseUnderConsignment
Inventory subject to repurchase included in inventory $ 43,900,000amrk_InventorySubjecttoRepurchaseAgreement $ 27,700,000amrk_InventorySubjecttoRepurchaseAgreement