Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity (Narrative) (Details)

v2.4.1.9
Stockholders' Equity (Narrative) (Details) (USD $)
0 Months Ended 3 Months Ended 9 Months Ended 0 Months Ended 9 Months Ended
Mar. 20, 2015
Jun. 04, 2014
Mar. 14, 2014
Mar. 14, 2014
Jun. 04, 2014
Mar. 31, 2015
Feb. 12, 2014
Jul. 02, 2013
Mar. 31, 2014
Jun. 30, 2014
Mar. 17, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Common stock, shares outstanding           6,962,742us-gaap_CommonStockSharesOutstanding       6,962,742us-gaap_CommonStockSharesOutstanding 7,402,664us-gaap_CommonStockSharesOutstanding
Cancellation of shares by Former Parent, shares     (71,922)amrk_StockCanceledDuringPeriodShares (71,922)amrk_StockCanceledDuringPeriodShares              
Repurchase common stock   $ 2,200,000us-gaap_StockRepurchasedDuringPeriodValue                  
Stock repurchase related interest expense         20,000amrk_StockRepurchasedDuringPeriodInterestExpense            
Interest rate at second closing, percentage         4.00%amrk_PurchaseAgreementSharePurchaseInterestRate            
Dividends paid to SGI 300,000us-gaap_DividendsCommonStockCash                    
Cash dividend paid $ 0.05us-gaap_CommonStockDividendsPerShareCashPaid                    
Expiration period           10 years          
Shares granted           0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross          
Intrinsic value, balance           305,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue       407,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue  
Stock Appreciation Rights (SARs)                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Award vesting period           3 years          
Shares outstanding           8,990us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
         
Fair value assumptions, exercise price           $ 50.31us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
         
Intrinsic value, balance           0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
         
2014 Stock Award and Incentive Plan                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Maximum amount of shares per employee           250,000amrk_StockAwardProgramMaximumAmountofSharesAuthorizedPerEmployeePerYear
/ us-gaap_PlanNameAxis
= amrk_A2014StockAwardandIncentivePlanMember
         
Shares granted under the plan, shares           625,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
/ us-gaap_PlanNameAxis
= amrk_A2014StockAwardandIncentivePlanMember
         
Shares granted           0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_PlanNameAxis
= amrk_A2014StockAwardandIncentivePlanMember
         
Awards assumed from SGI spin-off | Stock Appreciation Rights (SARs)                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Total compensation cost not yet recognized, other than options           0us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember
/ us-gaap_PlanNameAxis
= amrk_AwardsAssumedfromSGIPlanrelatedtospinoffMember
         
Former Parent (SGI)                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Dividends paid to SGI           0us-gaap_DividendsCommonStockCash
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= amrk_FormerParentSGIMember
5,000,000us-gaap_DividendsCommonStockCash
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= amrk_FormerParentSGIMember
5,000,000us-gaap_DividendsCommonStockCash
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= amrk_FormerParentSGIMember
10,000,000us-gaap_DividendsCommonStockCash
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= amrk_FormerParentSGIMember
   
Non Employee Director Except Chairman of the Board | 2014 Stock Award and Incentive Plan                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Maximum grant date fair value           300,000amrk_StockAwardProgramMaximumAmountofGrantFairValuePerGranteePerYear
/ amrk_EmploymentClassificationsAxis
= amrk_NonEmployeeDirectorExceptChairmanoftheBoardMember
/ us-gaap_PlanNameAxis
= amrk_A2014StockAwardandIncentivePlanMember
         
Chairman of the Board | 2014 Stock Award and Incentive Plan                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Maximum grant date fair value           $ 600,000amrk_StockAwardProgramMaximumAmountofGrantFairValuePerGranteePerYear
/ amrk_EmploymentClassificationsAxis
= us-gaap_BoardOfDirectorsChairmanMember
/ us-gaap_PlanNameAxis
= amrk_A2014StockAwardandIncentivePlanMember
         
Auctentia SL                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Repurchase common stock, shares   373,513us-gaap_StockRepurchasedDuringPeriodShares
/ us-gaap_CounterpartyNameAxis
= amrk_AuctentiaSlMember
                 
Afinsa                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Repurchase common stock, shares   5,520us-gaap_StockRepurchasedDuringPeriodShares
/ us-gaap_CounterpartyNameAxis
= amrk_AfinsaMember