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Acquisitions And Other Investments (Narrative) (Detail) (USD $)	3 Months Ended			3 Months Ended				1 Months Ended		1 Months Ended		3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Panama Subsidiary [Member] Segment, Discontinued Operations [Member]	Mar. 31, 2013 Rock Extraction Business [Member] Panama Subsidiary [Member] Segment, Discontinued Operations [Member]	Mar. 31, 2012 Rock Extraction Business [Member] Panama Subsidiary [Member] Segment, Discontinued Operations [Member]	Dec. 31, 2012 Rock Extraction Business [Member] Panama Subsidiary [Member] Segment, Discontinued Operations [Member]	Mar. 31, 2013 Rock Extraction Business [Member] Beneficial Owner [Member] Segment, Discontinued Operations [Member]	Dec. 31, 2012 Go Green [Member]	Dec. 02, 2012 Go Green [Member]	Dec. 31, 2012 Dynamic Tower [Member]	Dec. 02, 2012 Dynamic Tower [Member]	Mar. 31, 2013 2012 Acquisitions [Member]	Mar. 31, 2013 EC Source [Member] Earn-out Arrangements [Member]	Mar. 31, 2013 Optima [Member] Earn-out Arrangements [Member]
Business Acquisition [Line Items]
Effective date of acquisition								Dec. 01, 2012		Dec. 01, 2012
Business combination, percentage of voting interests acquired									100.00%		100.00%
Acquiree revenue since acquisition date												$ 43,100,000
Acquiree net income since acquisition date												1,800,000
Change in range of outcomes, contingent consideration, reasons													the Company remeasured the contingent consideration liability for EC Source Services LLC ("EC Source") using currently available facts and circumstances, including recent and expected future performance	the contingent consideration liability for Optima Network Services, Inc. ("Optima") was remeasured and settled in full during the first quarter of 2013 as a result of an amendment to the Optima purchase agreement effective February 28, 2013
Less than wholly owned subsidiary, ownership percentage			60.00%
Equity method investment, ownership percentage				34.00%			20.40%
Related party revenues				0	800,000
Related party receivables, equity method investee				3,700,000		3,700,000
Asset impairment charges, cost method investments	0	0
Asset impairment charges, equity method investments	$ 0	$ 0