CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $)
In Thousands, unless otherwise specified
Total
Common Stock
Treasury Stock
Additional Capital
Accumulated Other Comprehensive Loss
Accumulated Deficit
Comprehensive Income
Balance at Dec. 31, 2008 $ 269,518 $ 21 $ (853) $ 437,979 $ (1,763) $ (165,866)  
Balance (in shares) at Dec. 31, 2008   20,930 (56)        
Increase (Decrease) in Stockholders' Equity              
Common stock issued in equity offering, net of costs 52,487 3   52,484      
Common stock issued in equity offering, net of costs (in shares)   2,875          
Common stock issued on exercise of stock options and warrants 1,479     1,479      
Common stock issued on exercise of stock options and warrants (in shares)   137          
Common stock issued in connection with Enliven earnout (in shares)   13          
Adjustment to Enliven earnout (382)     (382)      
Common stock issued under employee stock purchase plan 130     130      
Common stock issued under employee stock purchase plan (in shares)   9          
Common stock issued on vesting of restricted stock (in shares)   7          
Common stock issued pursuant to restricted stock agreement, net of shares tendered to satisfy required tax withholding (890)     (890)      
Common stock issued pursuant to restricted stock agreement, net of shares tendered to satisfy required tax withholding (in shares)   74          
Share-based compensation 3,983     3,983      
Comprehensive income:              
Foreign currency translation adjustment (67)       (67)   (67)
Reclassification of unrealized gain (loss) on interest rate swaps (net of tax benefit (expense) of $903 and ($276) for the year ended 2010 and 2009, respectively) 407       407   407
Net income 20,501         20,501 20,501
Total comprehensive income 20,841           20,841
Balance at Dec. 31, 2009 347,166 24 (853) 494,783 (1,423) (145,365)  
Balance (in shares) at Dec. 31, 2009   24,045 (56)        
Increase (Decrease) in Stockholders' Equity              
Common stock issued in equity offering, net of costs 107,917 4   107,913      
Common stock issued in equity offering, net of costs (in shares)   3,651          
Common stock issued on exercise of stock options and warrants 7,818 1   7,817      
Common stock issued on exercise of stock options and warrants (in shares)   753          
Common stock issued in connection with Enliven earnout (in shares)   41          
Common stock issued under employee stock purchase plan 128     128      
Common stock issued under employee stock purchase plan (in shares)   5          
Common stock issued on vesting of restricted stock (in shares)   10          
Common stock issued pursuant to restricted stock agreement, net of shares tendered to satisfy required tax withholding (1,620)     (1,620)      
Common stock issued pursuant to restricted stock agreement, net of shares tendered to satisfy required tax withholding (in shares)   74          
Tax benefit from exercise of non-qualified stock options and vesting of restricted stock 879     879      
Purchase of treasury stock (13,148)   (13,148)        
Purchase of treasury stock (in shares)     (601)        
Share-based compensation 4,805     4,805      
Comprehensive income:              
Foreign currency translation adjustment 36       36   36
Reclassification of unrealized gain (loss) on interest rate swaps (net of tax benefit (expense) of $903 and ($276) for the year ended 2010 and 2009, respectively) 1,362       1,362   1,362
Net income 41,569         41,569 41,569
Total comprehensive income 42,967           42,967
Balance at Dec. 31, 2010 496,912 29 (14,001) 614,705 (25) (103,796)  
Balance (in shares) at Dec. 31, 2010   28,579 (657)        
Increase (Decrease) in Stockholders' Equity              
Common stock issued on exercise of stock options and warrants 212     212      
Common stock issued on exercise of stock options and warrants (in shares)   16          
Common stock issued under employee stock purchase plan 180     180      
Common stock issued under employee stock purchase plan (in shares)   6          
Common stock issued on vesting of restricted stock (in shares)   32          
Common stock issued pursuant to restricted stock agreement, net of shares tendered to satisfy required tax withholding (1,129)     (1,129)      
Common stock issued pursuant to restricted stock agreement, net of shares tendered to satisfy required tax withholding (in shares)   74          
Purchase of treasury stock (21,547)   (21,547)        
Purchase of treasury stock (in shares)     (847)        
Share-based compensation 12,430     12,430      
Comprehensive income:              
Foreign currency translation adjustment (3,747)       (3,747)   (3,747)
Unrealized loss on derivatives, (net of tax expense of $31) (284)       (284)   (284)
Unrealized gain on available for sale securities 275       275   275
Net income 24,484         24,484 24,484
Total comprehensive income 20,728           20,728
Balance at Dec. 31, 2011 $ 507,786 $ 29 $ (35,548) $ 626,398 $ (3,781) $ (79,312)  
Balance (in shares) at Dec. 31, 2011   28,707 (1,504)