Earnings Per Share (Computation of Basic and Diluted) (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Numerator:    
Net income (loss) $ 13,627 $ 14,580
Denominator:    
Weighted-average shares outstanding - basic (shares) 18,475,507 17,950,843
Effect of dilutive stock options (shares) 474,000 598,000
Weighted-average shares outstanding - diluted (shares) 18,949,594 18,549,458
Basic earnings per share (in dollars per share) $ 0.74 $ 0.81
Diluted earnings per share (in dollars per share) $ 0.72 $ 0.79