Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity (Option Activity Rollforward) (Details)

v2.4.1.9
Stockholders' Equity (Option Activity Rollforward) (Details) (USD $)
 6 Months Ended 3 Months Ended 6 Months Ended
Dec. 31, 2014
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2013
Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]          
Options, beginning balance 230,787us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber        
Granted through stock option plan 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross        
Exercised 0us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised        
Cancellations, expirations and forfeitures (660)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod        
Options, ending balance 230,127us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber 230,127us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber      
Shares exercisable at end of the period 158,213us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber 158,213us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]          
Weighted Average Exercise Price, beginning balance (in dollars per share) $ 10.00us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice        
Weighted Average Exercise Price, Granted (in dollars per share) $ 0.00us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice        
Weighted Average Exercise Price, Exercised (in dollars per share) $ 0.00us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice        
Weighted Average Exercise Price, Cancellations, expirations and forfeitures (in dollars per share) $ 48.02us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice        
Weighted Average Exercise Price, ending balance (in dollars per share) $ 9.89us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice $ 9.89us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice      
Weighted Average Exercise Price, Shares exercisable at end of period $ 10.60us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice $ 10.60us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice      
Intrinsic value, balance $ 213,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue $ 213,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue     $ 407,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
Intrinsic Value, Shares exercisable at end of period 155,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1 155,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1      
Weighted Average per share Grant Date Fair Value, beginning balance (in dollars per share) $ 5.98amrk_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageGrantDateFairValue        
Weighted Average per share Grant Date Fair Value, ending balance (in dollars per share) $ 6.00amrk_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageGrantDateFairValue $ 6.00amrk_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageGrantDateFairValue      
Weighted Average per share Grant Date Fair Value, Shares exercisable at end of period (in dollars per share) $ 5.80amrk_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageGrantDateFairValue $ 5.80amrk_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageGrantDateFairValue      
Awards assumed from SGI spin-off          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Total compensation cost not yet recognized 400,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
/ us-gaap_PlanNameAxis
= amrk_AwardsAssumedfromSGIPlanrelatedtospinoffMember 		400,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
/ us-gaap_PlanNameAxis
= amrk_AwardsAssumedfromSGIPlanrelatedtospinoffMember 		     
Stock Options          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense 77,200us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember 		37,600us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember 		0us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember 		0us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember 		 
Period for recognition of nonvested awards 2 years 9 months 25 days        
Stock Options | Former Parent SGI Plans          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense 0us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= amrk_FormerParentSGIPlansMember 		0us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= amrk_FormerParentSGIPlansMember 		0us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= amrk_FormerParentSGIPlansMember 		0us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= amrk_FormerParentSGIPlansMember 		 
Stock Options | Awards assumed from SGI spin-off          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense $ 77,200us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= amrk_AwardsAssumedfromSGIPlanrelatedtospinoffMember 		$ 37,600us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= amrk_AwardsAssumedfromSGIPlanrelatedtospinoffMember 		$ 0us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= amrk_AwardsAssumedfromSGIPlanrelatedtospinoffMember 		$ 0us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= amrk_AwardsAssumedfromSGIPlanrelatedtospinoffMember