Benefit Plans (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Multi-employer plans
Plan contributions	$ 9,676	$ 9,295	$ 9,046
Health Plan
Multi-employer plans
Plan contributions	4,843	4,585	4,472
Other plans
Multi-employer plans
Plan contributions	3,300	3,181	3,125
Pension Plan
Multi-employer plans
Plan contributions	$ 1,533	$ 1,529	$ 1,449

Amount of contributions made to the multiemployer plan by all employers who participate in the plan. 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 7
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=49170332&loc=SL14450678-114947

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