Accrued Workers' Compensation Accrued Wokers' Compensation (Schedule of Assumptions Used) (Details) (Workers' Compensation [Member])	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Workers' Compensation [Member]
Accrued Workers' Compensation [Line Items]
Discount rate	4.54%	5.10%	5.96%
Cost escalation rate	3.00%	3.00%	3.00%

The interest rate used to adjust for the time value of money for the plan.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph j

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (k)(1)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

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Balance Type:	na
Period Type:	instant