Amount of contributions made to multiemployer plans by the employer. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=14450570&loc=SL14450702-114947

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 9

-URI http://asc.fasb.org/extlink&oid=14450570&loc=SL14450691-114947

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 5

-Subparagraph (e)(1)

-URI http://asc.fasb.org/extlink&oid=14450570&loc=SL14450657-114947

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

Pension And Postretirement Benefit Costs (Schedule Of Multiemployer Plans) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Multiemployer Plans [Line Items]
Contributions	$ 299,076	$ 253,404	$ 275,603
Collective bargaining agreement expiring 3/31/2015 [Member]
Multiemployer Plans [Line Items]
Percentage required by collective bargaining agreement	35.00%
Collective bargaining agreement expiring 4/30/2014 [Member]
Multiemployer Plans [Line Items]
Percentage required by collective bargaining agreement	65.00%
Central States, Southeast, and Southwest Areas Pension Plan [Member]
Multiemployer Plans [Line Items]
Contributions	261,694	222,748	241,585
Other funds [Member]
Multiemployer Plans [Line Items]
Contributions	$ 37,382	$ 30,656	$ 34,018