Contingencies Contingencies (Details) (USD $)		12 Months Ended	3 Months Ended
Nov. 30, 2011	Dec. 31, 2011 General and Administrative Expense [Member] Environmental Issue [Member] Pending Litigation [Member] New Idria Mercury Mine [Member]	Jun. 30, 2013 Other Liabilities [Member] Environmental Issue [Member] Pending Litigation [Member] New Idria Mercury Mine [Member]
Loss Contingencies [Line Items]
Expense related to remedial investigation and feasibility study		$ 1,900,000
Payments charged against the reserve			500,000
Estimate of EPA's interim removal project costs	$ 500,000

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9, 10, 11, 12

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14435-108349

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 9

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14557-108349

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