Multiemployer Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Multiemployer Pension Plans [Member]
Multiemployer Plans [Line Items]
Multiemployer Plan, Period Contributions	$ 215	$ 229	$ 209
Multiemployer Plans Period Contributions Significance Of Contributions	false
Multiemployer Health Plans [Member]
Multiemployer Plans [Line Items]
Multiemployer Plan, Period Contributions	$ 731	$ 735	$ 703

Amount of contributions made to multiemployer plans for each period for which a statement of income is presented. An employer may disclose total contributions to multiemployer plans without disaggregating the amounts attributable to pension plans and other postretirement benefit plans.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

-Section 50

-Paragraph 1

-SubTopic 80

-Topic 715

-URI http://asc.fasb.org/extlink&oid=6958064&loc=d3e29142-114947

Name:	us-gaap_MultiemployerPlanPeriodContributions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration