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 $)	6 Months Ended		12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Jun. 30, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets - future and forward contracts	$ 19,108,000		$ 26,296,000
Derivative liabilities	35,189,000us-gaap_DerivativeLiabilities		32,782,000us-gaap_DerivativeLiabilities
Payments to acquire other investments	1,111,000	0	1,600,000
Realized gains on cost method investment	0
Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Inventory	223,377,000		172,990,000
Total assets valued at fair value	241,489,000		195,174,000
Liability on borrowed metals	5,684,000		8,709,000
Product financing arrangement	80,660,000		24,610,000
Liability on margin accounts	5,123,000		8,983,000
Total liabilities, valued at fair value	121,533,000		66,101,000
Level 1 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Inventory	223,377,000		172,990,000
Total assets valued at fair value	241,489,000		195,174,000
Liability on borrowed metals	5,684,000		8,709,000
Product financing arrangement	80,660,000		24,610,000
Liability on margin accounts	5,123,000		8,983,000
Total liabilities, valued at fair value	121,533,000		66,101,000
Level 2 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Inventory	0		0
Total assets valued at fair value	0		0
Liability on borrowed metals	0		0
Product financing arrangement	0		0
Liability on margin accounts	0		0
Total liabilities, valued at fair value	0		0
Level 3 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Inventory	0		0
Total assets valued at fair value	0		0
Liability on borrowed metals	0		0
Product financing arrangement	0		0
Liability on margin accounts	0		0
Total liabilities, valued at fair value	0		0
Derivative Asset Open Purchases And Sales Commitments \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets - future and forward contracts	2,428,000
Derivative Asset Open Purchases And Sales Commitments \| Level 1 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets - future and forward contracts	2,428,000
Derivative Asset Open Purchases And Sales Commitments \| Level 2 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets - future and forward contracts	0
Derivative Asset Open Purchases And Sales Commitments \| Level 3 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets - future and forward contracts	0
Forward contracts \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets - future and forward contracts	9,510,000		22,170,000
Forward contracts \| Level 1 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets - future and forward contracts	9,510,000		22,170,000
Forward contracts \| Level 2 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets - future and forward contracts	0		0
Forward contracts \| Level 3 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets - future and forward contracts	0		0
Future contracts \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets - future and forward contracts	6,174,000		14,000
Future contracts \| Level 1 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets - future and forward contracts	6,174,000		14,000
Future contracts \| Level 2 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets - future and forward contracts	0		0
Future contracts \| Level 3 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets - future and forward contracts	0		0
Future contracts \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities			8,078,000
Future contracts \| Level 1 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities			8,078,000
Future contracts \| Level 2 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities			0
Future contracts \| Level 3 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities			0
Forward contracts \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	46,000		14,873,000
Forward contracts \| Level 1 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	46,000		14,873,000
Forward contracts \| Level 2 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0		0
Forward contracts \| Level 3 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0		0
Open sales and purchase commitments \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	30,020,000		848,000
Open sales and purchase commitments \| Level 1 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	30,020,000		848,000
Open sales and purchase commitments \| Level 2 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0		0
Open sales and purchase commitments \| Level 3 \| Fair Value on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	$ 0		$ 0