SEGMENT REPORTING - Summarized Operating Results and Certain Financial Position Data of Company's Reportable Business Segments (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2015	Jul. 31, 2014	Jan. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 97,434,000	$ 102,030,000	$ 182,921,000	$ 153,221,000
Cost of revenues	68,941,000	80,466,000	133,261,000	121,607,000
Gross profit	28,493,000	21,564,000	49,660,000	31,614,000
Selling, general and administrative expenses	4,848,000	4,481,000	10,387,000	7,859,000
Income (loss) from operations	23,645,000	17,083,000	39,273,000	23,755,000
Other income, net	128,000	41,000	212,000	63,000
INCOME BEFORE INCOME TAXES	23,773,000	17,124,000	39,485,000	23,818,000
Income tax expense	7,939,000	5,104,000	12,800,000	6,997,000
Net income	15,834,000	12,020,000	26,685,000	16,821,000
Amortization of purchased intangibles	104,000	61,000	164,000	121,000
Depreciation	140,000	141,000	258,000	283,000
Property, plant and equipment additions	1,297,000	114,000	2,503,000	199,000
Goodwill	22,887,000	18,476,000	22,887,000	18,476,000	$ 18,476,000
Total assets	380,058,000	408,300,000	380,058,000	408,300,000	$ 391,193,000
Power Industry Services [Member]
Segment Reporting Information [Line Items]
Revenues	93,471,000	100,418,000	176,355,000	150,242,000
Cost of revenues	66,136,000	79,261,000	128,515,000	119,311,000
Gross profit	27,335,000	21,157,000	47,840,000	30,931,000
Selling, general and administrative expenses	2,849,000	2,769,000	6,432,000	4,556,000
Income (loss) from operations	24,486,000	18,388,000	41,408,000	26,375,000
Other income, net	301,000	40,000	379,000	62,000
INCOME BEFORE INCOME TAXES	24,787,000	18,428,000	41,787,000	26,437,000
Amortization of purchased intangibles	104,000	61,000	164,000	121,000
Depreciation	95,000	96,000	170,000	193,000
Property, plant and equipment additions	1,285,000	61,000	2,410,000	88,000
Goodwill	22,887,000	18,476,000	22,887,000	18,476,000
Total assets	310,410,000	368,450,000	310,410,000	368,450,000
Telecommunications Infrastructure Services [Member]
Segment Reporting Information [Line Items]
Revenues	3,963,000	1,612,000	6,566,000	2,979,000
Cost of revenues	2,805,000	1,205,000	4,746,000	2,296,000
Gross profit	1,158,000	407,000	1,820,000	683,000
Selling, general and administrative expenses	415,000	309,000	718,000	660,000
Income (loss) from operations	743,000	98,000	1,102,000	23,000
INCOME BEFORE INCOME TAXES	743,000	98,000	1,102,000	23,000
Depreciation	42,000	42,000	82,000	86,000
Property, plant and equipment additions	10,000	53,000	91,000	61,000
Total assets	2,910,000	2,351,000	2,910,000	2,351,000
Other [Member]
Segment Reporting Information [Line Items]
Selling, general and administrative expenses	1,584,000	1,403,000	3,237,000	2,643,000
Income (loss) from operations	(1,584,000)	(1,403,000)	(3,237,000)	(2,643,000)
Other income, net	(173,000)	1,000	(167,000)	1,000
INCOME BEFORE INCOME TAXES	(1,757,000)	(1,402,000)	(3,404,000)	(2,642,000)
Depreciation	3,000	3,000	6,000	4,000
Property, plant and equipment additions	2,000		2,000	50,000
Total assets	$ 66,738,000	$ 37,499,000	$ 66,738,000	$ 37,499,000