Supplemental Inventory Information (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]
Precious metals stated at LIFO cost	$ 9,819	$ 5,460
Market value per ounce, Silver (in dollars per ounce)	28.37	30.20
Market value per ounce, Gold (in dollars per ounce)	1,595.30	1,675.40
Market value per ounce, Palladium (in dollars per ounce)	767.50	702.85

The amount of LIFO (last in first out) inventory present at the reporting date when inventory is also valued using different valuation methods.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6361739&loc=d3e7789-107766

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Section A

-Paragraph 9

-Chapter 3

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant