SEGMENT REPORTING (Details) - USD ($)
$ in Thousands
 3 Months Ended
Apr. 30, 2017
Apr. 30, 2016
Jan. 31, 2017
Segment Reporting Information      
Revenues $ 230,489 $ 130,348  
Cost of revenues 190,393 102,046  
GROSS PROFIT 40,096 28,302  
Selling, general and administrative expenses 9,489 7,047  
INCOME FROM OPERATIONS 30,607 21,255  
Other income, net 1,218 37  
INCOME BEFORE INCOME TAXES 31,825 21,292  
Income tax expense 11,076 7,172  
NET INCOME 20,749 14,120  
Amortization of intangibles 183 321  
Depreciation 572 434  
Property, plant and equipment additions 1,863 245  
Current assets 643,671 400,116 $ 587,949
Current liabilities 384,679 218,346 350,724
Goodwill 34,913 36,813 34,913
Total assets 709,926 467,979 $ 652,972
Power Services      
Segment Reporting Information      
Revenues 210,789 108,099  
Cost of revenues 173,248 83,698  
GROSS PROFIT 37,541 24,401  
Selling, general and administrative expenses 5,205 3,234  
INCOME FROM OPERATIONS 32,336 21,167  
Other income, net 1,169 14  
INCOME BEFORE INCOME TAXES 33,505 21,181  
Amortization of intangibles 87 147  
Depreciation 170 132  
Property, plant and equipment additions 12 184  
Current assets 522,871 287,474  
Current liabilities 372,849 199,538  
Goodwill 20,548 22,526  
Total assets 552,134 318,248  
Industrial Services      
Segment Reporting Information      
Revenues 16,571 20,410  
Cost of revenues 14,741 16,988  
GROSS PROFIT 1,830 3,422  
Selling, general and administrative expenses 1,645 1,633  
INCOME FROM OPERATIONS 185 1,789  
INCOME BEFORE INCOME TAXES 185 1,789  
Amortization of intangibles 96 174  
Depreciation 335 258  
Property, plant and equipment additions 1,694 22  
Current assets 18,306 23,346  
Current liabilities 9,865 16,045  
Goodwill 14,365 14,287  
Total assets 52,358 57,613  
Telecom Services      
Segment Reporting Information      
Revenues 3,129 1,839  
Cost of revenues 2,404 1,360  
GROSS PROFIT 725 479  
Selling, general and administrative expenses 313 327  
INCOME FROM OPERATIONS 412 152  
INCOME BEFORE INCOME TAXES 412 152  
Depreciation 64 41  
Property, plant and equipment additions 155 39  
Current assets 4,032 5,502  
Current liabilities 1,728 803  
Total assets 5,149 6,073  
Other      
Segment Reporting Information      
Selling, general and administrative expenses 2,326 1,853  
INCOME FROM OPERATIONS (2,326) (1,853)  
Other income, net 49 23  
INCOME BEFORE INCOME TAXES (2,277) (1,830)  
Depreciation 3 3  
Property, plant and equipment additions 2    
Current assets 98,462 83,794  
Current liabilities 237 1,960  
Total assets 100,285 $ 86,045  
Intercompany Eliminations      
Segment Reporting Information      
Revenues $ 1,700