General - Contributions to Revenues and Profits Since Acquisitions (Details) (Schultz Mechanical Contractors, Inc. [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015
Schultz Mechanical Contractors, Inc. [Member]
Business Acquisition [Line Items]
Revenues	$ 517
Net loss	$ (7)

This element represents the amount of earnings or loss of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(1)

-URI http://asc.fasb.org/extlink&oid=25497992&loc=d3e1392-128463

Name:	us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration