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Equity Incentive Plans - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Total unrecognized compensation expense employee stock option plans $ 800,000    
Number of awards granted 764,000 1,181,000  
Weighted average grant date fair value of award granted $ 8.25 $ 4.51  
Minimum      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Vesting period 1 year    
Maximum      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Vesting period 4 years    
Employee Stock Options      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Share-based compensation expenses $ 1,500,000 $ 2,300,000 $ 4,400,000
Weighted average period for unrecognized compensation expense related to grants of stock options 1 year 6 months    
Employee Stock Options | Minimum      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Vesting period 4 years    
Employee Stock Options | Maximum      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Vesting period 5 years    
Restricted Stock And Restricted Stock Units      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Performance-based restricted stock and restricted stock units, eliminated minimum vesting period under amended 2004 plan 3 years    
Share-based compensation expenses $ 3,800,000 2,100,000 400,000
Weighted average period for unrecognized compensation expense related to grants of stock options 1 year 9 months 18 days    
Total unrecognized compensation expense related to grants of restricted stock and restricted stock units $ 4,700,000    
Shares vested related to grants of restricted stock and restricted stock units $ 3,500,000 $ 1,600,000 $ 800,000
Performance Restricted Stock Units      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Vesting period 3 years    
Share-based compensation expenses $ 0    
Performance period to grant award 1 year    
Number of awards granted 447,000    
Weighted average grant date fair value of award granted $ 8.39    
Performance Restricted Stock Units | Minimum      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Share award grant percentage 0.00%    
Performance Restricted Stock Units | Maximum      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Share award grant percentage 200.00%    
2000 Plan | Employee Stock Options      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Contractual term of stock options 10 years    
2000 Plan | Class A common stock      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Common stock shares authorized under 2000 plan and 2004 plan 11,500,000    
2004 Plan      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Share-based compensation award extended expiration date May 29, 2024    
2004 Plan | Employee Stock Options      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Contractual term of stock options 10 years    
Vesting period 4 years    
2004 Plan | Class A common stock      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Common stock shares authorized under 2000 plan and 2004 plan 10,000,000