Impact of the Adoption on Consolidated Balance Sheet (Detail) - USD ($)
$ in Thousands
Oct. 31, 2018
Aug. 01, 2018
Jul. 31, 2018
Oct. 31, 2017
Jul. 31, 2017
ASSETS          
Inventories, net $ 29,969   $ 47,786    
Prepaid expenses and other current assets 34,187   13,415    
Total current assets 276,054   264,281    
Total assets 827,727   827,050    
Liabilities          
Other current liabilities 38,408   42,125    
Total current liabilities 280,197   276,356    
Total liabilities 687,098   684,230    
Stockholders' equity          
Accumulated deficit (7,365,332)   (7,363,569)    
Total stockholders' equity 105,431   107,628 $ 58,314 $ 62,971
Total liabilities, contingently redeemable preferred stock and stockholders' equity 827,727   827,050    
Calculated under Revenue Guidance in Effect before Topic 606 [Member]          
ASSETS          
Inventories, net     47,786    
Prepaid expenses and other current assets     13,415    
Total current assets     264,281    
Total assets     827,050    
Liabilities          
Other current liabilities     42,125    
Total current liabilities     276,356    
Total liabilities     684,230    
Stockholders' equity          
Accumulated deficit     (7,363,569)    
Total stockholders' equity     107,628    
Total liabilities, contingently redeemable preferred stock and stockholders' equity     $ 827,050    
Accounting Standards Update 2014-09          
ASSETS          
Inventories, net   $ 26,553      
Prepaid expenses and other current assets   37,456      
Total current assets   267,089      
Total assets   829,858      
Liabilities          
Other current liabilities   38,795      
Total current liabilities   273,026      
Total liabilities   680,900      
Stockholders' equity          
Accumulated deficit   (7,357,431)      
Total stockholders' equity   113,766      
Total liabilities, contingently redeemable preferred stock and stockholders' equity   829,858      
Accounting Standards Update 2014-09 | Calculated under Revenue Guidance in Effect before Topic 606 [Member]          
ASSETS          
Inventories, net 51,392        
Prepaid expenses and other current assets 11,524        
Total current assets 274,814        
Total assets 826,487        
Liabilities          
Other current liabilities 44,041        
Total current liabilities 285,830        
Total liabilities 692,731        
Stockholders' equity          
Accumulated deficit (7,372,205)        
Total stockholders' equity 98,558        
Total liabilities, contingently redeemable preferred stock and stockholders' equity 826,487        
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606          
ASSETS          
Inventories, net (21,423) (21,233)      
Prepaid expenses and other current assets 22,663 24,041      
Total current assets 1,240 2,808      
Total assets 1,240 2,808      
Liabilities          
Other current liabilities (5,633) (3,330)      
Total current liabilities (5,633) (3,330)      
Total liabilities (5,633) (3,330)      
Stockholders' equity          
Accumulated deficit 6,873 6,138      
Total stockholders' equity 6,873 6,138      
Total liabilities, contingently redeemable preferred stock and stockholders' equity $ 1,240 $ 2,808