Nature of Operations and Basis of Presentation - Schedule of Goodwill (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill, Beginning balance	$ 143,160us-gaap_Goodwill
Acquisition date adjustment	1,380
Foreign currency translation adjustment	(8,851)us-gaap_GoodwillTranslationAdjustments
Goodwill, Ending balance	135,689us-gaap_Goodwill
Natural Gas Operations [Member]
Goodwill [Line Items]
Goodwill, Beginning balance		10,095
Goodwill, Ending balance	10,095	10,095
Construction Services [Member]
Goodwill [Line Items]
Goodwill, Beginning balance	133,065
Acquisition date adjustment	1,380
Foreign currency translation adjustment	(8,851)
Goodwill, Ending balance	$ 125,594

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

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Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 25

-Paragraph 16

-URI http://asc.fasb.org/extlink&oid=34752592&loc=d3e961-128460

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