Quarterly report pursuant to Section 13 or 15(d)

Net Income Per Share (Details)

v2.4.0.8
Net Income Per Share (Details) (USD $)
In Thousands, except Per Share data, unless otherwise specified
 3 Months Ended 6 Months Ended
Jun. 30, 2013
Jun. 30, 2012
Jun. 30, 2013
Jun. 30, 2012
Numerator [Abstract]        
Numerator for basic and diluted income per share - net income $ 13,831 $ 14,167 $ 24,685 $ 24,440
Denominator [Abstract]        
Denominator for basic income per share - weighted-average shares 30,161 28,908 29,838 28,800
Denominator for diluted income per share - adjusted weighted-average shares 30,736 29,445 30,477 29,402
Basic income per share (dollars per share) $ 0.46 $ 0.49 $ 0.83 $ 0.85
Diluted income per share (dollars per share) $ 0.45 $ 0.48 $ 0.81 $ 0.83
Total number anti-dilutive options, non-vested shares, and performance shares excluded from income per diluted share computation     176 313
Stock Option [Member]
        
Denominator [Abstract]        
Effect of dilutive stock options and non-vested shares 476 474 537 533
Total number anti-dilutive options, non-vested shares, and performance shares excluded from income per diluted share computation     176 213
Key Employee Performance Share Based Plan [Member]
        
Denominator [Abstract]        
Effect of dilutive stock options and non-vested shares 9 0 6 0
Total number anti-dilutive options, non-vested shares, and performance shares excluded from income per diluted share computation       19
Nonvested Shares [Member]
        
Denominator [Abstract]        
Effect of dilutive stock options and non-vested shares 90 63 96 69
Total number anti-dilutive options, non-vested shares, and performance shares excluded from income per diluted share computation       81