Quarterly report pursuant to Section 13 or 15(d)

Hedging Transactions (Offsetting Assets and Liabilities) (Details)

v2.4.1.9
Hedging Transactions (Offsetting Assets and Liabilities) (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Jun. 30, 2014
Offsetting Assets and Liabilities [Line Items]    
Gross derivative receivable $ 18,627us-gaap_DerivativeFairValueOfDerivativeAsset $ 26,296us-gaap_DerivativeFairValueOfDerivativeAsset
Amounts netted (12,237)us-gaap_DerivativeAssetFairValueGrossLiability (4,112)us-gaap_DerivativeAssetFairValueGrossLiability
Net derivative receivable 6,390us-gaap_DerivativeAssets 22,184us-gaap_DerivativeAssets
Gross derivative payable 17,938us-gaap_DerivativeFairValueOfDerivativeLiability 16,525us-gaap_DerivativeFairValueOfDerivativeLiability
Amounts netted (1,557)us-gaap_DerivativeLiabilityFairValueGrossAsset (174)us-gaap_DerivativeLiabilityFairValueGrossAsset
Cash collateral pledge (3,876)us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset 16,431us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset
Net derivative payables 12,505us-gaap_DerivativeLiabilities 32,782us-gaap_DerivativeLiabilities
Open sales and purchase commitments    
Offsetting Assets and Liabilities [Line Items]    
Gross derivative receivable 9,482us-gaap_DerivativeFairValueOfDerivativeAsset
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_OpenPurchasesAndSalesCommitmentsMember
26,282us-gaap_DerivativeFairValueOfDerivativeAsset
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_OpenPurchasesAndSalesCommitmentsMember
Amounts netted (5,102)us-gaap_DerivativeAssetFairValueGrossLiability
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_OpenPurchasesAndSalesCommitmentsMember
(4,112)us-gaap_DerivativeAssetFairValueGrossLiability
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_OpenPurchasesAndSalesCommitmentsMember
Net derivative receivable 4,380us-gaap_DerivativeAssets
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_OpenPurchasesAndSalesCommitmentsMember
22,170us-gaap_DerivativeAssets
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_OpenPurchasesAndSalesCommitmentsMember
Gross derivative payable 1,322us-gaap_DerivativeFairValueOfDerivativeLiability
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_OpenPurchasesAndSalesCommitmentsMember
1,022us-gaap_DerivativeFairValueOfDerivativeLiability
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_OpenPurchasesAndSalesCommitmentsMember
Amounts netted (762)us-gaap_DerivativeLiabilityFairValueGrossAsset
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_OpenPurchasesAndSalesCommitmentsMember
(174)us-gaap_DerivativeLiabilityFairValueGrossAsset
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_OpenPurchasesAndSalesCommitmentsMember
Cash collateral pledge 0us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_OpenPurchasesAndSalesCommitmentsMember
0us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_OpenPurchasesAndSalesCommitmentsMember
Net derivative payables 560us-gaap_DerivativeLiabilities
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_OpenPurchasesAndSalesCommitmentsMember
848us-gaap_DerivativeLiabilities
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_OpenPurchasesAndSalesCommitmentsMember
Margin accounts    
Offsetting Assets and Liabilities [Line Items]    
Gross derivative payable 10,870us-gaap_DerivativeFairValueOfDerivativeLiability
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_DerivativeLiabilityMarginAccountsMember
15,751us-gaap_DerivativeFairValueOfDerivativeLiability
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_DerivativeLiabilityMarginAccountsMember
Amounts netted 0us-gaap_DerivativeLiabilityFairValueGrossAsset
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_DerivativeLiabilityMarginAccountsMember
0us-gaap_DerivativeLiabilityFairValueGrossAsset
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_DerivativeLiabilityMarginAccountsMember
Cash collateral pledge (3,876)us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_DerivativeLiabilityMarginAccountsMember
(6,768)us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_DerivativeLiabilityMarginAccountsMember
Net derivative payables 6,994us-gaap_DerivativeLiabilities
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_DerivativeLiabilityMarginAccountsMember
8,983us-gaap_DerivativeLiabilities
/ us-gaap_DerivativeInstrumentRiskAxis
= amrk_DerivativeLiabilityMarginAccountsMember
Future contracts    
Offsetting Assets and Liabilities [Line Items]    
Gross derivative receivable 9,145us-gaap_DerivativeFairValueOfDerivativeAsset
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
0us-gaap_DerivativeFairValueOfDerivativeAsset
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
Amounts netted (7,135)us-gaap_DerivativeAssetFairValueGrossLiability
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
0us-gaap_DerivativeAssetFairValueGrossLiability
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
Net derivative receivable 2,010us-gaap_DerivativeAssets
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
0us-gaap_DerivativeAssets
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
Gross derivative payable 0us-gaap_DerivativeFairValueOfDerivativeLiability
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
(15,121)us-gaap_DerivativeFairValueOfDerivativeLiability
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
Amounts netted 0us-gaap_DerivativeLiabilityFairValueGrossAsset
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
0us-gaap_DerivativeLiabilityFairValueGrossAsset
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
Cash collateral pledge    23,199us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
Net derivative payables 0us-gaap_DerivativeLiabilities
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
8,078us-gaap_DerivativeLiabilities
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
Forward contracts    
Offsetting Assets and Liabilities [Line Items]    
Gross derivative receivable 0us-gaap_DerivativeFairValueOfDerivativeAsset
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForwardContractsMember
14us-gaap_DerivativeFairValueOfDerivativeAsset
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForwardContractsMember
Amounts netted 0us-gaap_DerivativeAssetFairValueGrossLiability
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForwardContractsMember
0us-gaap_DerivativeAssetFairValueGrossLiability
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForwardContractsMember
Net derivative receivable 0us-gaap_DerivativeAssets
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForwardContractsMember
14us-gaap_DerivativeAssets
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForwardContractsMember
Gross derivative payable 5,746us-gaap_DerivativeFairValueOfDerivativeLiability
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForwardContractsMember
14,873us-gaap_DerivativeFairValueOfDerivativeLiability
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForwardContractsMember
Amounts netted (795)us-gaap_DerivativeLiabilityFairValueGrossAsset
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForwardContractsMember
0us-gaap_DerivativeLiabilityFairValueGrossAsset
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForwardContractsMember
Cash collateral pledge 0us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForwardContractsMember
0us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForwardContractsMember
Net derivative payables $ 4,951us-gaap_DerivativeLiabilities
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForwardContractsMember
$ 14,873us-gaap_DerivativeLiabilities
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForwardContractsMember