Earnings Per Share (Calculation of Basic and Diluted EPS) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Net income	$ 11,333	$ 8,575	$ 30,070	$ 24,704
Average Common Shares:
Basic (weighted-average outstanding shares)	12,069	11,903	12,040	11,887
Dilutive potential common shares from stock options, shares	160	153	156	160
Diluted (weighted-average outstanding shares)	12,229	12,056	12,196	12,047
Basic earnings per share (in dollars per share)	$ 0.94	$ 0.72	$ 2.50	$ 2.08
Diluted earnings per share (in dollars per share)	$ 0.93	$ 0.71	$ 2.47	$ 2.05