Earnings Per Share (Calculation of Basic and Diluted EPS) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share [Abstract]
Net income	$ 11,787	$ 9,344	$ 18,737	$ 16,129
Average Common Shares:
Basic (weighted-average outstanding shares)	12,044	11,884	12,025	11,879
Dilutive potential common shares from stock options, shares	156	174	154	163
Diluted (weighted-average outstanding shares)	12,200	12,058	12,179	12,042
Basic earnings per share (in dollars per share)	$ 0.98	$ 0.79	$ 1.56	$ 1.36
Diluted earnings per share (in dollars per share)	$ 0.97	$ 0.77	$ 1.54	$ 1.34