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 (Fair Value Measurement, Recurring and Nonrecurring) (Details)

Summary of Significant Accounting Policies (Fair Value Measurement, Recurring and Nonrecurring) (Details) (USD $)	3 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Fair Value on a Recurring Basis	Sep. 30, 2014 Level 1 Fair Value on a Recurring Basis	Jun. 30, 2014 Level 1 Fair Value on a Recurring Basis	Sep. 30, 2014 Level 2 Fair Value on a Recurring Basis	Jun. 30, 2014 Level 2 Fair Value on a Recurring Basis	Sep. 30, 2014 Level 3 Fair Value on a Recurring Basis	Jun. 30, 2014 Level 3 Fair Value on a Recurring Basis	Jun. 30, 2014 Fair value Fair Value on a Recurring Basis	Sep. 30, 2014 Derivative Asset Open Purchases And Sales Commitments Fair Value on a Recurring Basis	Sep. 30, 2014 Derivative Asset Open Purchases And Sales Commitments Level 1 Fair Value on a Recurring Basis	Sep. 30, 2014 Derivative Asset Open Purchases And Sales Commitments Level 2 Fair Value on a Recurring Basis	Sep. 30, 2014 Derivative Asset Open Purchases And Sales Commitments Level 3 Fair Value on a Recurring Basis	Sep. 30, 2014 Forward contracts Fair Value on a Recurring Basis	Sep. 30, 2014 Forward contracts Level 1 Fair Value on a Recurring Basis	Jun. 30, 2014 Forward contracts Level 1 Fair Value on a Recurring Basis	Sep. 30, 2014 Forward contracts Level 2 Fair Value on a Recurring Basis	Jun. 30, 2014 Forward contracts Level 2 Fair Value on a Recurring Basis	Sep. 30, 2014 Forward contracts Level 3 Fair Value on a Recurring Basis	Jun. 30, 2014 Forward contracts Level 3 Fair Value on a Recurring Basis	Jun. 30, 2014 Forward contracts Fair value Fair Value on a Recurring Basis	Sep. 30, 2014 Future contracts Fair Value on a Recurring Basis	Sep. 30, 2014 Future contracts Level 1 Fair Value on a Recurring Basis	Jun. 30, 2014 Future contracts Level 1 Fair Value on a Recurring Basis	Sep. 30, 2014 Future contracts Level 2 Fair Value on a Recurring Basis	Jun. 30, 2014 Future contracts Level 2 Fair Value on a Recurring Basis	Sep. 30, 2014 Future contracts Level 3 Fair Value on a Recurring Basis	Jun. 30, 2014 Future contracts Level 3 Fair Value on a Recurring Basis	Jun. 30, 2014 Future contracts Fair value Fair Value on a Recurring Basis	Jun. 30, 2014 Future contracts Level 1 Fair Value on a Recurring Basis	Jun. 30, 2014 Future contracts Level 2 Fair Value on a Recurring Basis	Jun. 30, 2014 Future contracts Level 3 Fair Value on a Recurring Basis	Jun. 30, 2014 Future contracts Fair value Fair Value on a Recurring Basis	Jun. 30, 2014 Forward contracts Level 1 Fair Value on a Recurring Basis	Jun. 30, 2014 Forward contracts Level 2 Fair Value on a Recurring Basis	Jun. 30, 2014 Forward contracts Level 3 Fair Value on a Recurring Basis	Jun. 30, 2014 Forward contracts Fair value Fair Value on a Recurring Basis	Sep. 30, 2014 Open sales and purchase commitments Fair Value on a Recurring Basis	Sep. 30, 2014 Open sales and purchase commitments Level 1 Fair Value on a Recurring Basis	Jun. 30, 2014 Open sales and purchase commitments Level 1 Fair Value on a Recurring Basis	Sep. 30, 2014 Open sales and purchase commitments Level 2 Fair Value on a Recurring Basis	Jun. 30, 2014 Open sales and purchase commitments Level 2 Fair Value on a Recurring Basis	Sep. 30, 2014 Open sales and purchase commitments Level 3 Fair Value on a Recurring Basis	Jun. 30, 2014 Open sales and purchase commitments Level 3 Fair Value on a Recurring Basis	Jun. 30, 2014 Open sales and purchase commitments Fair value Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Inventory			$ 158,424,000	$ 158,424,000	$ 172,990,000	$ 0	$ 0	$ 0	$ 0	$ 172,990,000
Derivative assets - future and forward contracts											2,628,000	2,628,000	0	0	16,510,000	16,510,000	22,170,000	0	0	0	0	0	27,071,000	27,071,000	14,000	0	0	0	0	14,000
Total assets valued at fair value			204,633,000	204,633,000	195,174,000	0	0	0	0	195,174,000
Liability on borrowed metals			11,998,000	11,998,000	8,709,000	0	0	0	0	8,709,000
Product financing arrangement			20,613,000	20,613,000	24,610,000	0	0	0	0	24,610,000
Liability on margin accounts			5,333,000	5,333,000	8,983,000	0	0	0	0	8,983,000
Derivative liabilities																															8,078,000	0	0	8,078,000	14,873,000	0	0	14,873,000	49,139,000	49,139,000	848,000	0	0	0	0	848,000
Total liabilities, valued at fair value			87,083,000	87,083,000	66,101,000	0	0	0	0	66,101,000
Payments to acquire other investments	1,111,000	0
Realized gains on cost method investment	$ 0