Acquisitions And Other Investments (Narrative) (Detail) (USD $)	3 Months Ended		9 Months Ended			1 Months Ended	3 Months Ended		9 Months Ended				3 Months Ended		1 Months Ended		3 Months Ended					1 Months Ended	3 Months Ended		9 Months Ended	3 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Panama Subsidiary [Member] Segment, Discontinued Operations [Member]	Nov. 30, 2010 EC Source Services Llc Investee [Member]	Sep. 30, 2012 Rock Extraction Business [Member] Segment, Discontinued Operations [Member]	Sep. 30, 2011 Rock Extraction Business [Member] Segment, Discontinued Operations [Member]	Sep. 30, 2012 Rock Extraction Business [Member] Segment, Discontinued Operations [Member]	Sep. 30, 2011 Rock Extraction Business [Member] Segment, Discontinued Operations [Member]	Dec. 31, 2011 Rock Extraction Business [Member] Segment, Discontinued Operations [Member]	Dec. 31, 2010 Rock Extraction Business [Member] Panama Subsidiary [Member] Segment, Discontinued Operations [Member]	Sep. 30, 2012 Rock Extraction Business [Member] Panama Subsidiary [Member] Accounts Receivable [Member] Segment, Discontinued Operations [Member]	Dec. 31, 2010 Rock Extraction Business [Member] Beneficial Owner [Member] Segment, Discontinued Operations [Member]	May 31, 2011 EC Source [Member]	Apr. 30, 2011 EC Source [Member]	Jun. 30, 2011 EC Source [Member]	May 02, 2011 EC Source [Member]	Sep. 30, 2012 EC Source [Member] Management [Member]	May 02, 2011 EC Source [Member] Management [Member]	May 02, 2011 EC Source [Member] Earn-out Arrangements [Member]	Apr. 30, 2011 Fabcor [Member]	Jun. 30, 2012 Fabcor [Member]	Apr. 30, 2011 Fabcor [Member] Earn-out Arrangements [Member]	Sep. 30, 2012 2011 Acquisitions [Member]	Jun. 30, 2012 Halsted [Member]	Jun. 30, 2012 Optima [Member] Earn-out Arrangements [Member]
Business Acquisition [Line Items]
Payments to acquire equity method investments						$ 10,000,000
Equity method investment, ownership percentage						33.00%						34.00%		20.40%
Equity method investment, additional information						two-year option
Date of acquisition agreement																Apr. 29, 2011
Effective date of acquisition															May 02, 2011							Apr. 01, 2011
Business combination, step acquisition, equity interest in acquiree, percentage																		33.00%
Business combination, step acquisition, equity interest in acquiree, fair value of equity investment																		39,600,000
Business combination, step acquisition, percentage of voting interests acquired																		67.00%
Business combination, step acquisition, cumulative percentage ownership after all transactions															100.00%
Equity issued in business combination, number of shares issued															5,129,642
Equity issued in business combination, fair value																		94,200,000
Acquisition payments in cash																		300,000				24,200,000
Purchase price consideration, adjustment																							1,400,000				1,500,000
Estimated fair value of contingent consideration																					25,000,000			16,900,000
Earn-out period																					5 years			5 years
Assumed debt, equipment loans payable, related party																				8,600,000
Assumed debt, equipment loans payable, related party																			8,600,000
Gain on remeasurement of equity interest in acquiree	0	0	0	29,041,000													29,000,000
Debt assumed and repaid																						7,000,000
Purchase price allocation, adjustment, liabilities																										3,900,000
Acquiree revenue since acquisition date																									164,700,000
Acquiree net income since acquisition date																									11,600,000
Less than wholly owned subsidiary, ownership percentage					60.00%
Related party revenues							800,000	700,000	2,000,000	2,400,000
Related party receivables, equity method investee							3,900,000		3,900,000		6,700,000
Due from related party, equity method investee, non-current portion							1,100,000		1,100,000		4,300,000
Other asset impairment charges, disposal group													4,400,000
Asset impairment charges, cost method investments	0	0	0	0
Asset impairment charges, equity method investments	$ 0	$ 0	$ 0	$ 0