Earnings Per Share (Computation of Basic and Diluted) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Numerator:
Net income	$ 14,928	$ 13,643
Denominator:
Weighted-average shares outstanding - basic (shares)	17,966,000	18,476,000
Effect of dilutive shares (shares)	248,000	474,000
Weighted-average shares outstanding - diluted (shares)	18,214,000	18,950,000
Basic earnings per share (in dollars per share)	$ 0.83	$ 0.74
Diluted earnings per share (in dollars per share)	$ 0.82	$ 0.72
Anti-dilutive shares excluded (shares)	51,275	0