Mergers and Acquisitions (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2011
Acquisitions Material in the Aggregate
Unaudited Pro Forma Summary Financial Information
Revenues	$ 3,894,867
Income from Construction Operations	178,631
Net Income	88,123
Basic earnings per common share (in dollars per share)	$ 1.87
Diluted earnings per common share (in dollars per share)	$ 1.84
GreenStar Services Corporation
Unaudited Pro Forma Summary Financial Information
Revenues	4,068,804
Income from Construction Operations	207,579
Net Income	108,712
Basic earnings per common share (in dollars per share)	$ 2.30
Diluted earnings per common share (in dollars per share)	$ 2.27
Lunda Construction Company
Unaudited Pro Forma Summary Financial Information
Revenues	3,872,694
Income from Construction Operations	191,565
Net Income	$ 98,270
Basic earnings per common share (in dollars per share)	$ 2.08
Diluted earnings per common share (in dollars per share)	$ 2.05

The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a 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)(2)-(3)

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

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