Annual report pursuant to Section 13 and 15(d)

Shareholders' Equity, Stock Options and Net Income per Share - Net Income per Share (Details)

v2.4.0.8
Shareholders' Equity, Stock Options and Net Income per Share - Net Income per Share (Details) (USD $)
In Thousands, except Per Share data, unless otherwise specified
 3 Months Ended 12 Months Ended
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2012
Sep. 30, 2012
Jun. 30, 2012
Mar. 31, 2012
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]                      
Numerator for basic and diluted income per share - net income $ 15,584 $ 14,197 $ 13,831 $ 10,855 $ 15,961 $ 12,267 $ 14,167 $ 10,273 $ 54,467 $ 52,668 $ 47,199
Denominator for basic income per share - weighted-average shares                 30,135 28,967 29,052
Denominator for diluted income per share - adjusted weighted-average shares                 30,762 29,536 29,435
Basic net income per share $ 0.51 $ 0.47 $ 0.46 $ 0.37 $ 0.55 $ 0.42 $ 0.49 $ 0.36 $ 1.81 $ 1.82 $ 1.62
Diluted net income per share $ 0.50 $ 0.46 $ 0.45 $ 0.36 $ 0.54 $ 0.41 $ 0.48 $ 0.35 $ 1.77 $ 1.78 $ 1.60
Total number anti-dilutive options and non-vested shares excluded from income per diluted share computation                 192 248 649
Equity Option [Member]
                      
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]                      
Weighted Average Number Diluted Shares Outstanding Adjustment                 507 492 333
Total number anti-dilutive options and non-vested shares excluded from income per diluted share computation                 192 226 649
Key Employee Performance Share Based Plan [Member]
                      
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]                      
Weighted Average Number Diluted Shares Outstanding Adjustment                 12 41 25
Total number anti-dilutive options and non-vested shares excluded from income per diluted share computation                   22  
Nonvested Shares and Deferred Stock Units [Member]
                      
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]                      
Weighted Average Number Diluted Shares Outstanding Adjustment                 108 36 25