Earnings Per Share (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Jun. 30, 2012
Jun. 30, 2011
Basic earnings per share        
Income available to common stockholders, Net Income $ 6,620 $ 4,720 $ 11,742 $ 9,655
Income available to common stockholders, Shares 12,452,112 9,336,727 10,894,419 9,336,727
Income available to common stockholders, Per Share $ 0.53 $ 0.51 $ 1.08 $ 1.03
Effect of dilutive securities        
Options to purchase common stock, Net Income            
Options to purchase common stock, Shares 282,976 190,976 281,373 251,176
Options to purchase common stock, Per Share            
Diluted earnings per share        
Income available to common stockholders, Net Income $ 6,620 $ 4,720 $ 11,742 $ 9,655
Income available to common stockholders, Shares 12,735,088 9,527,703 11,175,792 9,587,903
Income available to common stockholders, Per Share $ 0.52 $ 0.50 $ 1.05 $ 1.01