Quarterly report pursuant to Section 13 or 15(d)

Income Taxes (Narrative) (Details)

v2.4.1.9
Income Taxes (Narrative) (Details) (USD $)
 3 Months Ended 9 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Mar. 31, 2015
Mar. 31, 2014
Jun. 30, 2014
Operating Loss Carryforwards [Line Items]          
Effective tax rate 9.50%us-gaap_EffectiveIncomeTaxRateContinuingOperations 40.40%us-gaap_EffectiveIncomeTaxRateContinuingOperations 31.70%us-gaap_EffectiveIncomeTaxRateContinuingOperations 40.50%us-gaap_EffectiveIncomeTaxRateContinuingOperations  
Valuation allowance $ (100,000)us-gaap_DeferredTaxAssetsValuationAllowance   $ (100,000)us-gaap_DeferredTaxAssetsValuationAllowance    
Unrecognized tax benefits 400,000us-gaap_UnrecognizedTaxBenefits   400,000us-gaap_UnrecognizedTaxBenefits    
Penalties and interest expense accrued 0us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued 0us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued 0us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued 0us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued  
Penalties and interest expense recognized 300,000us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued   300,000us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued    
Income taxes receivable from Former Parent 4,017,000us-gaap_DueFromRelatedPartiesCurrent   4,017,000us-gaap_DueFromRelatedPartiesCurrent   3,139,000us-gaap_DueFromRelatedPartiesCurrent
Operating loss related to state and city deferred tax asset 400,000us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal   400,000us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal    
Domestic Tax Authority          
Operating Loss Carryforwards [Line Items]          
Income taxes receivable 5,600,000us-gaap_IncomeTaxReceivable
/ us-gaap_IncomeTaxAuthorityAxis
= us-gaap_DomesticCountryMember 		  5,600,000us-gaap_IncomeTaxReceivable
/ us-gaap_IncomeTaxAuthorityAxis
= us-gaap_DomesticCountryMember 		   
State and Local Jurisdiction          
Operating Loss Carryforwards [Line Items]          
Operating loss carryforwards 6,300,000us-gaap_OperatingLossCarryforwards
/ us-gaap_IncomeTaxAuthorityAxis
= us-gaap_StateAndLocalJurisdictionMember 		  6,300,000us-gaap_OperatingLossCarryforwards
/ us-gaap_IncomeTaxAuthorityAxis
= us-gaap_StateAndLocalJurisdictionMember 		   
Income Tax Sharing Agreement | SGI (Former Parent)          
Operating Loss Carryforwards [Line Items]          
Income taxes receivable from Former Parent $ 4,000,000us-gaap_DueFromRelatedPartiesCurrent
/ us-gaap_RelatedPartyTransactionAxis
= amrk_IncomeTaxSharingAgreementMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= amrk_FormerParentSGIMember 		  $ 4,000,000us-gaap_DueFromRelatedPartiesCurrent
/ us-gaap_RelatedPartyTransactionAxis
= amrk_IncomeTaxSharingAgreementMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= amrk_FormerParentSGIMember