Earnings Per Share (Calculation of Basic and Diluted EPS) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Net income	$ 13,367	$ 11,333	$ 29,800	$ 30,070
Average Common Shares:
Basic (weighted-average outstanding shares)	12,050,000	12,069,000	12,077,000	12,040,000
Dilutive potential common shares from stock options, shares	156,000	160,000	174,000	156,000
Diluted (weighted-average outstanding shares)	12,206,000	12,229,000	12,251,000	12,196,000
Basic earnings per share (in dollars per share)	$ 1.11	$ 0.94	$ 2.47	$ 2.50
Diluted earnings per share (in dollars per share)	$ 1.10	$ 0.93	$ 2.43	$ 2.47
Stock options excluded from diluted earnings per share calculation because the effect would be anti-dilutive	66,750	0	22,250	15,118