Discontinued Operations - Schedule of Results of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jul. 31, 2015	Jul. 31, 2015
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Total income on discontinued operations	$ 5,356	$ 5,372
Geoconstruction Business Segment [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Revenue	22,860	42,952
Cost of revenues (exclusive of depreciation and amortization, shown below)	(13,710)	(31,155)
Selling, general and administrative expenses (exclusive of depreciation and amortization, shown below)	(1,411)	(3,018)
Depreciation and amortization	(1,634)	(3,239)
Equity in earnings of affiliates	170	907
Other income (expense) items	772	684
Total operating income on discontinued operations before income taxes	7,047	7,131
Income tax expense	(1,691)	(1,759)
Total income on discontinued operations	$ 5,356	$ 5,372