A-Mark Precious Metals, Inc. Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies (Narrative) (Details)

Summary of Significant Accounting Policies (Narrative) (Details) (USD $)	0 Months Ended	3 Months Ended		9 Months Ended
	Sep. 19, 2014 tranch	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015 Segment	Mar. 31, 2014	Jun. 30, 2014	Feb. 18, 2014
Property, Plant and Equipment [Line Items]
Number of reportable segments				1us-gaap_NumberOfReportableSegments
Premium on metals position		$ 3,668,000		$ 3,668,000		$ 3,285,000
Commemorative coin inventory, held at lower of cost or market		65,000		65,000		2,564,000
Borrowed metals		6,500,000amrk_BorrowedMetals		6,500,000amrk_BorrowedMetals		8,700,000amrk_BorrowedMetals
Inventories loaned under consignment		5,600,000		5,600,000		11,100,000
Product under financing arrangement		48,100,000amrk_ProductUnderFinancingArrangement		48,100,000amrk_ProductUnderFinancingArrangement		24,600,000amrk_ProductUnderFinancingArrangement
Inventory subject to repurchase included in inventory		43,900,000		43,900,000		27,700,000
Ownership percentage							2.50%
Long-term investments		1,611,000us-gaap_CostMethodInvestments		1,611,000us-gaap_CostMethodInvestments		500,000us-gaap_CostMethodInvestments	500,000us-gaap_CostMethodInvestments
Receivable		6,163,000us-gaap_DueFromRelatedParties		6,163,000us-gaap_DueFromRelatedParties		5,852,000us-gaap_DueFromRelatedParties
Long-term receivable		700,000		700,000		0
Payables		10,000		10,000		272,000
Advertising expense		200,000us-gaap_AdvertisingExpense	300,000us-gaap_AdvertisingExpense	500,000us-gaap_AdvertisingExpense	600,000us-gaap_AdvertisingExpense
Shipping, handling costs		1,500,000	1,200,000	4,700,000	4,200,000
Number of tranches	2
Payment for closing of Tranche A	2,000,000
Payments to acquire Tranche A	1,100,000
Exclusive supplier agreement, period, Tranche A	5 years
Exclusive supplier agreement, period	3 years
Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives of related assets				3 years
Estimated useful lives of intangibles				4 years
Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives of related assets				5 years
Estimated useful lives of intangibles				15 years
Common Class A
Property, Plant and Equipment [Line Items]
Agreement to purchase noncontrolling interest, percentage	9.00%
Percentage of stock to be purchased for Tranche A	5.00%
Cost-method Investee
Property, Plant and Equipment [Line Items]
Receivable		9,900,000		9,900,000		2,600,000
Secured loans		900,000		900,000		0
Long-term receivable		700,000		700,000
Payables		12,900,000		12,900,000		3,500,000
Revenue from related party		124,700,000	60,200,000	352,000,000	143,400,000
Purchases from related party		$ 300,000	$ 100,000	$ 700,000	$ 2,000,000