Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity (Options Outstanding, Range of Exercise Prices and Other Details) (Details)

v2.4.1.9
Stockholders' Equity (Options Outstanding, Range of Exercise Prices and Other Details) (Details) (USD $)
 6 Months Ended
Dec. 31, 2014
Jun. 30, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]    
Stock options, Number of Shares Outstanding 230,127us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber 230,787us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Stock options outstanding, Weighted Average Remaining Contractual Life (years) 7 years 9 months 15 days  
Stock options outstanding, Weighted Average Exercise Price (in dollars per share) $ 9.89us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice $ 10.00us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Stock options exercisable, Number of Shares Exercisable 158,213us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber  
Stock options exercisable, Weighted Average Remaining Contractual Life (years) 7 years 9 months 9 days  
Stock options exercisable, Weighted Average Exercise Price (in dollars per share) $ 10.60us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice  
Price Range $0 - $10.00    
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]    
Stock options, Exercise Price Ranges, lower range limit (in dollars per share) $ 0us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= amrk_PriceRange1Member 		 
Stock options, Exercise Price Ranges, upper range limit (in dollars per share) $ 10us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= amrk_PriceRange1Member 		 
Stock options, Number of Shares Outstanding 134,239us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= amrk_PriceRange1Member 		 
Stock options outstanding, Weighted Average Remaining Contractual Life (years) 7 years 10 months 7 days  
Stock options outstanding, Weighted Average Exercise Price (in dollars per share) $ 8.39us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= amrk_PriceRange1Member 		 
Stock options exercisable, Number of Shares Exercisable 62,325us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= amrk_PriceRange1Member 		 
Stock options exercisable, Weighted Average Remaining Contractual Life (years) 7 years 10 months 19 days  
Stock options exercisable, Weighted Average Exercise Price (in dollars per share) $ 8.44us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= amrk_PriceRange1Member 		 
Price Range $10.01 - $15.00    
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]    
Stock options, Exercise Price Ranges, lower range limit (in dollars per share) $ 10.01us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= amrk_PriceRange2Member 		 
Stock options, Exercise Price Ranges, upper range limit (in dollars per share) $ 15us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= amrk_PriceRange2Member 		 
Stock options, Number of Shares Outstanding 95,888us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= amrk_PriceRange2Member 		 
Stock options outstanding, Weighted Average Remaining Contractual Life (years) 7 years 8 months 14 days  
Stock options outstanding, Weighted Average Exercise Price (in dollars per share) $ 12.00us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= amrk_PriceRange2Member 		 
Stock options exercisable, Number of Shares Exercisable 95,888us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= amrk_PriceRange2Member 		 
Stock options exercisable, Weighted Average Remaining Contractual Life (years) 7 years 8 months 14 days  
Stock options exercisable, Weighted Average Exercise Price (in dollars per share) $ 12.00us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= amrk_PriceRange2Member