Segment Reporting - Summarized Operating Results and Certain Financial Position Data of Company's Reportable Continuing Business Segments (Detail) (USD $)	3 Months Ended								12 Months Ended
	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Segment Reporting Information [Line Items]
Revenues	$ 59,491,000	$ 63,452,000	$ 57,864,000	$ 46,648,000	$ 57,840,000	$ 74,486,000	$ 82,619,000	$ 63,690,000	$ 227,455,000	$ 278,635,000	$ 141,850,000
Cost of revenues									148,607,000	228,500,000	118,748,000
Gross profit	20,687,000	23,876,000	21,257,000	13,028,000	14,019,000	13,136,000	12,879,000	10,101,000	78,848,000	50,135,000	23,102,000
Selling, general and administrative expenses									12,918,000	14,350,000	11,186,000
Income (loss) from operations									65,930,000	35,785,000	11,916,000
Gains on the deconsolidation of VIEs									2,444,000
Other income (expense), net									961,000	(43,000)	48,000
Income (loss) from continuing operations before income taxes									69,335,000	35,742,000	11,964,000
Income tax expense									25,991,000	13,640,000	4,556,000
Income from continuing operations	10,032,000	12,449,000	13,923,000	6,940,000	5,861,000	5,713,000	5,981,000	4,547,000	43,344,000	22,102,000	7,408,000
Amortization of purchased intangible assets									243,000	243,000	334,000
Depreciation									549,000	522,000	455,000
Fixed asset additions									1,136,000	7,263,000	1,738,000
Goodwill	18,476,000				18,476,000				18,476,000	18,476,000	18,476,000
Total assets	323,306,000				234,724,000				323,306,000	234,724,000	205,252,000
Current assets	298,559,000				204,108,000				298,559,000	204,108,000	180,577,000
Current liabilities	165,236,000				115,546,000				165,236,000	115,546,000	104,279,000
Power Industry Services [Member]
Segment Reporting Information [Line Items]
Revenues									218,649,000	261,327,000	132,519,000
Cost of revenues									141,807,000	214,817,000	111,193,000
Telecommunications Infrastructure Services [Member]
Segment Reporting Information [Line Items]
Revenues									8,806,000	17,308,000	9,331,000
Cost of revenues									6,800,000	13,683,000	7,555,000
Operating Segments [Member] | Power Industry Services [Member]
Segment Reporting Information [Line Items]
Revenues									218,649,000	261,327,000	132,519,000
Cost of revenues									141,807,000	214,817,000	111,193,000
Gross profit									76,842,000	46,510,000	21,326,000
Selling, general and administrative expenses									7,575,000	7,950,000	6,235,000
Income (loss) from operations									69,267,000	38,560,000	15,091,000
Gains on the deconsolidation of VIEs									2,444,000
Other income (expense), net									958,000	(45,000)	33,000
Income (loss) from continuing operations before income taxes									72,669,000	38,515,000	15,124,000
Amortization of purchased intangible assets									243,000	243,000	334,000
Depreciation									366,000	290,000	207,000
Fixed asset additions									1,067,000	6,986,000	1,598,000
Goodwill	18,476,000				18,476,000				18,476,000	18,476,000	18,476,000
Total assets	276,744,000				186,284,000				276,744,000	186,284,000	164,049,000
Current assets	252,603,000				158,567,000				252,603,000	158,567,000	141,561,000
Current liabilities	163,534,000				110,828,000				163,534,000	110,828,000	101,709,000
Operating Segments [Member] | Telecommunications Infrastructure Services [Member]
Segment Reporting Information [Line Items]
Revenues									8,806,000	17,308,000	9,331,000
Cost of revenues									6,800,000	13,683,000	7,555,000
Gross profit									2,006,000	3,625,000	1,776,000
Selling, general and administrative expenses									1,331,000	1,628,000	1,586,000
Income (loss) from operations									675,000	1,997,000	190,000
Income (loss) from continuing operations before income taxes									675,000	1,997,000	190,000
Depreciation									180,000	229,000	244,000
Fixed asset additions									69,000	277,000	136,000
Total assets	1,989,000				4,032,000				1,989,000	4,032,000	3,121,000
Current assets	1,293,000				3,486,000				1,293,000	3,486,000	2,626,000
Current liabilities	511,000				1,346,000				511,000	1,346,000	1,065,000
Other [Member]
Segment Reporting Information [Line Items]
Selling, general and administrative expenses									4,012,000	4,772,000	3,365,000
Income (loss) from operations									(4,012,000)	(4,772,000)	(3,365,000)
Other income (expense), net									3,000	2,000	15,000
Income (loss) from continuing operations before income taxes									(4,009,000)	(4,770,000)	(3,350,000)
Depreciation									3,000	3,000	4,000
Fixed asset additions											4,000
Total assets	44,573,000				44,408,000				44,573,000	44,408,000	38,082,000
Current assets	44,663,000				42,055,000				44,663,000	42,055,000	36,390,000
Current liabilities	$ 1,191,000				$ 3,372,000				$ 1,191,000	$ 3,372,000	$ 1,505,000