Goodwill and Other Intangible Assets (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended
	Jun. 30, 2013 Acquisitions During 2013 [Member]	Jun. 30, 2013 Bottom Line Services [Member]	Jun. 30, 2013 Bottom Line Services [Member]	Mar. 31, 2013 Dynamic Tower [Member]	Jun. 30, 2013 Dynamic Tower [Member]	Sep. 30, 2012 Globetec [Member]
Goodwill And Other Intangible Assets [Line Items]
Intangible assets, explanation of significant additions	During the second quarter of 2013, the Company acquired Big Country, an oil and gas pipeline and facility construction services company, and Data Cell, a telecommunications infrastructure company.
Purchase price consideration, adjustment		$ 2.4		$ 4.7
Business combination, provisional information, initial accounting incomplete, nature of adjustments			$2.3 million of additional pre-acquisition project cost liabilities were recorded as a result of the ongoing review of the acquired net working capital of BLS. In addition, accounts receivable were reduced by $0.1 million. These adjustments resulted in an increase to the previously recorded amount of BLS goodwill of $2.4 million.		recorded $4.7 million of post-closing purchase price adjustments relating to the 2012 acquisition of DTS during the first quarter of 2013 based on DTS's final closing tangible net worth and net working capital
Goodwill and intangible asset impairment, disposal group						$ 6.4