Segment Reporting - Summarized Operating Results and Certain Financial Position Data of Company's Reportable Continuing Business Segments (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2014	Jul. 31, 2013	Jan. 31, 2014
Segment Reporting Information [Line Items]
Revenues	$ 102,030,000	$ 57,864,000	$ 153,221,000	$ 104,512,000
Cost of revenues	80,466,000	36,607,000	121,607,000	70,227,000
Gross profit	21,564,000	21,257,000	31,614,000	34,285,000
Selling, general and administrative expenses	4,481,000	1,601,000	7,859,000	5,044,000
Income (loss) from operations	17,083,000	19,656,000	23,755,000	29,241,000
Gains on the deconsolidation of VIEs	0	1,324,000	0	2,444,000
Other income, net	41,000	410,000	63,000	566,000
Income (loss) before income taxes	17,124,000	21,390,000	23,818,000	32,251,000
Income tax expense	5,104,000	7,467,000	6,997,000	11,388,000
Net income	12,020,000	13,923,000	16,821,000	20,863,000
Amortization of purchased intangibles	61,000	61,000	121,000	121,000
Depreciation	141,000	136,000	283,000	265,000
Property, plant and equipment additions	114,000	174,000	199,000	851,000
Goodwill	18,476,000	18,476,000	18,476,000	18,476,000	18,476,000
Total assets	408,300,000	206,748,000	408,300,000	206,748,000	323,306,000
Power Industry Services [Member]
Segment Reporting Information [Line Items]
Revenues	100,418,000	55,520,000	150,242,000	99,289,000
Cost of revenues	79,261,000	34,804,000	119,311,000	66,050,000
Telecommunications Infrastructure Services [Member]
Segment Reporting Information [Line Items]
Revenues	1,612,000	2,344,000	2,979,000	5,223,000
Cost of revenues	1,205,000	1,803,000	2,296,000	4,177,000
Operating Segments [Member] | Power Industry Services [Member]
Segment Reporting Information [Line Items]
Revenues	100,418,000	55,520,000	150,242,000	99,289,000
Cost of revenues	79,261,000	34,804,000	119,311,000	66,050,000
Gross profit	21,157,000	20,716,000	30,931,000	33,239,000
Selling, general and administrative expenses	2,769,000	1,626,000	4,556,000	3,441,000
Income (loss) from operations	18,388,000	19,090,000	26,375,000	29,798,000
Gains on the deconsolidation of VIEs		1,324,000		2,444,000
Other income, net	40,000	409,000	62,000	564,000
Income (loss) before income taxes	18,428,000	20,823,000	26,437,000	32,806,000
Income tax expense	0	0	0	0
Net income	0	0	0	0
Amortization of purchased intangibles	61,000	61,000	121,000	121,000
Depreciation	96,000	89,000	193,000	172,000
Property, plant and equipment additions	61,000	141,000	88,000	807,000
Goodwill	18,476,000	18,476,000	18,476,000	18,476,000
Total assets	368,450,000	150,254,000	368,450,000	150,254,000
Operating Segments [Member] | Telecommunications Infrastructure Services [Member]
Segment Reporting Information [Line Items]
Revenues	1,612,000	2,344,000	2,979,000	5,223,000
Cost of revenues	1,205,000	1,803,000	2,296,000	4,177,000
Gross profit	407,000	541,000	683,000	1,046,000
Selling, general and administrative expenses	309,000	330,000	660,000	646,000
Income (loss) from operations	98,000	211,000	23,000	400,000
Gains on the deconsolidation of VIEs		0		0
Other income, net	0	0	0	0
Income (loss) before income taxes	98,000	211,000	23,000	400,000
Income tax expense	0	0	0	0
Net income	0	0	0	0
Amortization of purchased intangibles	0	0	0	0
Depreciation	42,000	46,000	86,000	91,000
Property, plant and equipment additions	53,000	33,000	61,000	44,000
Goodwill	0	0	0	0
Total assets	2,351,000	2,718,000	2,351,000	2,718,000
Other [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Cost of revenues	0	0	0	0
Gross profit	0	0	0	0
Selling, general and administrative expenses	1,403,000	(355,000)	2,643,000	957,000
Income (loss) from operations	(1,403,000)	355,000	(2,643,000)	(957,000)
Gains on the deconsolidation of VIEs		0		0
Other income, net	1,000	1,000	1,000	2,000
Income (loss) before income taxes	(1,402,000)	356,000	(2,642,000)	(955,000)
Income tax expense	0	0	0	0
Net income	0	0	0	0
Amortization of purchased intangibles	0	0	0	0
Depreciation	3,000	1,000	4,000	2,000
Property, plant and equipment additions	0	0	50,000	0
Goodwill	0	0	0	0
Total assets	$ 37,499,000	$ 53,776,000	$ 37,499,000	$ 53,776,000