REVENUE RECOGNITION REVENUE RECOGNITION - IMPACT OF ADOPTION - ADDITIONAL INFORMATION (Details) - USD ($)
$ in Thousands
3 Months Ended
Feb. 01, 2018
Apr. 30, 2018
Apr. 30, 2017
Jan. 31, 2018
Jan. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Total stockholders' equity $ 1,170,383 $ 1,163,271 $ 1,023,072 $ 1,132,336 $ 1,015,040
Revenue   289,207 260,995    
Cost of Revenue   114,092 $ 110,803    
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Total stockholders' equity 38,047 $ 56,737      
Revenue 17,200        
Deferred Costs 4,200        
Cost of Revenue 2,900        
Capitalized Contract Cost, Net 16,900        
Deferred income taxes $ 3,200