Quarterly report pursuant to Section 13 or 15(d)

Net Income Per Share (Details)

v3.8.0.1
Net Income Per Share (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Earnings Per Share, Basic, Two Class Method [Abstract]    
Net income and comprehensive income $ 17,741 $ 14,581
Income allocated to participating securities (145) (122)
Numerator for basic and diluted income per share - net income $ 17,596 $ 14,459
Denominator for basic income per share - weighted-average shares 29,375 29,998
Denominator for diluted income per share - adjusted weighted-average shares 29,480 30,106
Basic income per share (dollars per share) $ 0.60 $ 0.48
Diluted income per share (dollars per share) $ 0.60 $ 0.48
Total number anti-dilutive options, non-vested shares, and performance shares excluded from income per diluted share computation 87 297
Equity Option [Member]    
Earnings Per Share, Basic, Two Class Method [Abstract]    
Effect of dilutive stock options and non-vested shares 70 75
Total number anti-dilutive options, non-vested shares, and performance shares excluded from income per diluted share computation 67 282
Key Employee Performance Share Based Plan [Member]    
Earnings Per Share, Basic, Two Class Method [Abstract]    
Effect of dilutive stock options and non-vested shares 35 33
Total number anti-dilutive options, non-vested shares, and performance shares excluded from income per diluted share computation 11 15
Nonvested Shares and Deferred Stock Units [Member]    
Earnings Per Share, Basic, Two Class Method [Abstract]    
Total number anti-dilutive options, non-vested shares, and performance shares excluded from income per diluted share computation 9 0