SEGMENT REPORTING (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017	Jan. 31, 2018
Segment Reporting Information
Revenues	$ 136,670	$ 259,803	$ 278,036	$ 490,292
Cost of revenues	105,962	208,396	231,876	398,789
Gross profit	30,708	51,407	46,160	91,503
Selling, general and administrative expenses	10,378	10,799	20,015	20,289
Income (loss) from operations	20,330	40,608	26,145	71,214
Other income, net	2,928	1,311	3,692	2,529
Income (loss) before income taxes	23,258	41,919	29,837	73,743
Income tax expense	6,314	14,601	8,051	25,676
Net income	16,944	27,318	21,786	48,067
Amortization of purchased intangible assets	253	334	506	518
Depreciation	796	638	1,567	1,210
Property, plant and equipment additions	1,674	939	5,365	2,802
Current assets	453,213		453,213		$ 485,028
Current liabilities	139,842		139,842		183,211
Goodwill	34,329	34,913	34,329	34,913	34,329
Total assets	513,803	643,321	513,803	643,321	$ 542,670
Power Services
Segment Reporting Information
Revenues	105,051	238,850	227,538	449,639
Cost of revenues	79,162	189,266	187,458	362,515
Gross profit	25,889	49,584	40,080	87,124
Selling, general and administrative expenses	6,153	6,135	11,385	11,340
Income (loss) from operations	19,736	43,449	28,695	75,784
Other income, net	1,420	1,250	2,095	2,420
Income (loss) before income taxes	21,156	44,699	30,790	78,204
Amortization of purchased intangible assets	88	88	175	175
Depreciation	189	184	365	354
Property, plant and equipment additions	716	203	1,542	215
Current assets	341,112		341,112
Current liabilities	121,620		121,620
Goodwill	20,548	20,548	20,548	20,548
Total assets	369,714	519,518	369,714	519,518
Industrial Services
Segment Reporting Information
Revenues	28,037	17,058	44,486	33,629
Cost of revenues	24,037	16,096	39,686	30,837
Gross profit	4,000	962	4,800	2,792
Selling, general and administrative expenses	1,953	1,758	3,788	3,404
Income (loss) from operations	2,047	(796)	1,012	(612)
Other income, net	1,400		1,400
Income (loss) before income taxes	3,447	(796)	2,412	(612)
Amortization of purchased intangible assets	165	246	331	343
Depreciation	511	384	1,024	719
Property, plant and equipment additions	711	643	3,275	2,337
Current assets	29,983		29,983
Current liabilities	16,378		16,378
Goodwill	13,781	14,365	13,781	14,365
Total assets	60,077	46,048	60,077	46,048
Telecom Services
Segment Reporting Information
Revenues	3,582	3,895	6,012	7,024
Cost of revenues	2,763	3,034	4,732	5,437
Gross profit	819	861	1,280	1,587
Selling, general and administrative expenses	388	398	850	711
Income (loss) from operations	431	463	430	876
Income (loss) before income taxes	431	463	430	876
Depreciation	92	67	171	131
Property, plant and equipment additions	247	93	547	248
Current assets	4,041		4,041
Current liabilities	902		902
Total assets	5,676	4,087	5,676	4,087
Other
Segment Reporting Information
Selling, general and administrative expenses	1,884	2,508	3,992	4,834
Income (loss) from operations	(1,884)	(2,508)	(3,992)	(4,834)
Other income, net	108	61	197	109
Income (loss) before income taxes	(1,776)	(2,447)	(3,795)	(4,725)
Depreciation	4	3	7	6
Property, plant and equipment additions			1	2
Current assets	78,077		78,077
Current liabilities	942		942
Total assets	78,336	73,668	78,336	73,668
Intercompany Eliminations
Segment Reporting Information
Revenues	$ 400	$ 100	$ 400	$ 1,600