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STOCK BASED COMPENSATION - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares reserved for future issuance 8,054,670    
Term of offering period 6 months    
Employee Stock Purchase Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares authorized 1,000,000    
Percentage of discount to market price 85.00%    
Maximum payroll deductions during the offering period, per employee $ 5,000    
Shares available for issuance (in shares) 202,364    
Stock issued during period (in shares) 89,100 68,039 60,189
Stock Options [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized compensation expenses related to stock options $ 38,000,000    
Weighted average period of recognition for unrecognized compensation expenses 2 years 10 months 17 days    
Stock Options [Member] | Director      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period 1 year    
Stock Options [Member] | Officers And Employees      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period 5 years    
Stock Options [Member] | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Maximum term of an option granted under any plan 8 years    
Stock Options [Member] | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Maximum term of an option granted under any plan 10 years    
Restricted Stock Units (RSUs) [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted average period of recognition for unrecognized compensation expenses 2 years 10 months 10 days    
Ratio of share reserve related to RSUs granted 200.00%    
Unrecognized compensation expenses related to RSUs $ 7,400,000    
Fair value of units vested (in shares)     $ 2,000,000
Units vested (in shares) 0 0  
Restricted Stock Units (RSUs) [Member] | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period 3 years    
Restricted Stock Units (RSUs) [Member] | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period 5 years