REVENUE RECOGNITION REVENUE RECOGNITION - ASU NO. 2014-09 ADOPTION BALANCE SHEET (Details) - USD ($)
$ in Thousands
Apr. 30, 2018
Feb. 01, 2018
Jan. 31, 2018
Apr. 30, 2017
Jan. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Accounts receivable, net $ 303,108 $ 350,006 $ 296,324    
Contract assets 87,963 69,217 0    
Deferred cost of revenue 8,501 8,152 6,096    
Prepaid expenses and other current assets 77,058 81,261 82,090    
Long-term deferred cost of revenue 4,478 4,997 2,804    
Deferred income taxes   28,630      
Other assets 93,486 66,949 82,915    
Accrued expenses and other current liabilities 193,828 174,203 224,765    
Contract liabilities 332,139 335,624 196,107    
Long-term contract liabilities 28,354 31,037 24,519    
Deferred income taxes   36,268      
Total stockholders' equity 1,163,271 1,170,383 1,132,336 $ 1,023,072 $ 1,015,040
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]          
Accounts receivable, net 4,503 53,682      
Contract assets 87,963 69,217      
Deferred cost of revenue (737) 2,056      
Prepaid expenses and other current assets (2,001) (829)      
Long-term deferred cost of revenue 2,341 2,193      
Deferred income taxes   (2,248)      
Other assets 16,430 14,912      
Accrued expenses and other current liabilities (40,740) (46,062)      
Contract liabilities 87,437 139,517      
Long-term contract liabilities 4,110 6,518      
Deferred income taxes   963      
Total stockholders' equity $ 56,737 $ 38,047      
Scenario, Previously Reported          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Deferred income taxes     30,878    
Other assets     52,037    
Accrued expenses and other current liabilities     220,265    
Deferred income taxes     35,305    
Total stockholders' equity     $ 1,132,336