Nature of Operations and Basis of Presentation - Schedule of Goodwill (Detail) - USD ($)	6 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015
Goodwill [Line Items]
Goodwill, Beginning balance		$ 143,160,000
Acquisition date adjustment	$ 0	1,380,000
Foreign currency translation adjustment		(14,656,000)
Goodwill, Ending balance	129,884,000	129,884,000
Natural Gas Operations [Member]
Goodwill [Line Items]
Goodwill, Beginning balance		10,095,000
Acquisition date adjustment		0
Foreign currency translation adjustment		0
Goodwill, Ending balance	10,095,000	10,095,000
Construction Services [Member]
Goodwill [Line Items]
Goodwill, Beginning balance		133,065,000
Acquisition date adjustment		1,380,000
Foreign currency translation adjustment		(14,656,000)
Goodwill, Ending balance	$ 119,789,000	$ 119,789,000