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Stock-Based Awards - Additional Information (Detail) (USD $)
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock-based compensation cost $ 5,667,000 $ 3,986,000
Stock Option [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Restricted stock awards, vesting period 4 years  
Stock options grant expiration period 10 years  
Stock granted 112,700 150,050
Weighted average exercise price $ 68.74 $ 26.72
Weighted average grant-date fair value $ 34.09 $ 11.06
Unrecognized compensation expense 15,300,000  
Weighted average period 3 years  
Stock-based compensation cost 1,400,000 1,800,000
Restricted Stock Awards [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock granted 370,350 517,850
Weighted average period 3 years  
Weighted average grant-date fair value $ 73.38 $ 28.81
Unrecognized compensation expense 53,800,000  
Restricted Stock Awards [Member] | Minimum [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Restricted stock awards, vesting period 2 years  
Restricted Stock Awards [Member] | Maximum [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Restricted stock awards, vesting period 4 years  
Performance-based Restricted Stock Awards [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Restricted stock awards, vesting period 3 years  
Stock granted 39,900  
Description of granting performance-based restricted stock awards to certain executive officers Also in March 2014, the Company granted performance-based restricted stock awards to certain executive officers, which allow the grant of up to an aggregate 39,900 restricted shares if certain performance goals and continued service requirements are met on or before March 31, 2015.  
Restricted stock awards vesting percentage for performance achievement 25.00%  
Employee Stock Purchase Plan [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Allocated shares, employees to purchase 400,000  
Percentage of purchase price of stock 85.00%  
Stock-based compensation cost $ 100,000 $ 0