v2.3.0.15
COMPENSATION PLANS (Details) (USD $)
3 Months Ended9 Months Ended3 Months Ended9 Months Ended3 Months Ended9 Months Ended
Sep. 30, 2011
Sep. 30, 2011
Common Stock awards
Sep. 30, 2011
Restricted common stock
Sep. 30, 2010
Restricted common stock
Sep. 30, 2011
Restricted common stock
Sep. 30, 2010
Restricted common stock
Mar. 31, 2011
Grants made to newly hired employees
Sep. 30, 2011
Grants made to newly hired employees
Sep. 30, 2011
Stock options
Y
Sep. 30, 2010
Stock options
Sep. 30, 2011
Stock options
Y
entity
Sep. 30, 2010
Stock options
Y
Compensation plans            
Common stock available for issuance (in shares)4,100,000           
Common stock shares approved by Board of Directors (in shares) 9,616          
Portion of shares vesting on each anniversary date of the grant      one-third    one-third  
The period over which grants vest (in years)      First three anniversary dates     
Typical minimum vesting period of awards (in years)       2    
Typical maximum vesting period of awards (in years)       4    
Total compensation expense  $ 800,000$ 700,000$ 2,700,000$ 2,100,000  $ 400,000$ 200,000$ 1,100,000$ 700,000
Total unrecognized compensation expense  3,500,000 3,500,000   2,500,000 2,500,000 
Non-vested restricted common stock, number of shares            
Non-vested restricted common stock, at beginning of period (in shares)    217,794       
Granted (in shares)    61,585       
Vested (in shares)    (98,744)       
Forfeited (in shares)    (8,775)       
Non-vested restricted common stock, at end of period (in shares)  171,860 171,860       
Non-vested restricted common stock, additional disclosures            
Non-vested restricted common stock, at beginning of period (in dollars per share)    $ 27.96       
Granted (in dollars per share)    $ 35.80       
Vested (in dollars per share)    $ 28.11       
Forfeited (in dollars per share)  $ 30.77 $ 30.77       
Non-vested restricted common stock, at end of period (in dollars per share)  $ 30.53 $ 30.53       
The number of periods, at the anniversary dates of the grant, over which the award vests (in years)          three years 
Assumptions used to compute weighted average fair value of options granted            
Risk free interest rate (as a percent)          2.60%2.70%
Estimated volatility (as a percent)          56.60%56.70%
Expected option life (in years)          66
Number of peer companies used to determine estimated volatility when calculating fair value of options granted          3 
Stock option activity, number of shares            
Outstanding non-qualified stock options, at beginning of period (in shares)          273,851 
Granted (in shares)          102,196 
Exercised (in shares)          (14,739) 
Forfeited (in shares)          (6,969) 
Outstanding non-qualified stock options, at end of period (in shares)        354,339 354,339 
Vested or expected to vest, end of period (in shares)        339,487 339,487 
Exercisable non-qualified stock options, at end of period (in shares)        131,887 131,887 
Stock Options, Weighted Average Exercise Price            
Outstanding non-qualified stock options, at beginning of period (in dollars per share)          $ 22.69 
Granted (in dollars per share)        $ 35.69 $ 35.69 
Exercised (in dollars per share)        $ 22.33 $ 22.33 
Forfeited (in dollars per share)        $ 30.35 $ 30.35 
Outstanding non-qualified stock options, at end of period (in dollars per share)        $ 26.31 $ 26.31 
Vested or expected to vest, end of period (in dollars per share)        $ 26.00 $ 26.00 
Exercisable non-qualified stock options, at end of period (in dollars per share)        $ 22.00 $ 22.00 
Stock Options, Aggregate Intrinsic Value            
Outstanding non-qualified stock options, at end of period        619,153 619,153 
Vested or expected to vest, at end of period        617,544 617,544 
Exercisable non-qualified stock options, at end of period        $ 401,823 $ 401,823 
Stock Options, Weighted Average Remaining Contractual Life            
Outstanding non-qualified stock options, at end of period (in years)        8.2 8.2 
Vested or expected to vest, end of period (in years)          8.2 
Exercisable non-qualified stock options, at end of period (in years)          7.7 
Stock Options, Weighted Average Grant-Date Fair Value            
Outstanding non-qualified stock options, at beginning of period (in dollars per share)          $ 10.69 
Granted (in dollars per share)          $ 19.59 
Exercised (in dollars per share)          $ 10.02 
Forfeited (in dollars per share)          $ 16.29 
Outstanding non-qualified stock options, at end of period (in dollars per share)        $ 13.17 $ 13.17 
Vested or expected to vest, end of period (in dollars per share)          $ 12.95 
Exercisable non-qualified stock options, at end of period (in dollars per share)          $ 9.85