Earnings Per Share (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
Numerator:
Net Earnings	$ 11,792	$ 10,617	$ 33,110	$ 29,930
Denominator:
Basic - Weighted Average Shares Outstanding	18,120,729	18,267,828	18,201,291	18,288,083
Effect of dilutive securities:
Share-based compensation plans	514,558	543,810	526,527	535,662
Diluted - Weighted Average Shares Outstanding	18,635,287	18,811,638	18,727,818	18,823,745
Basic Earnings per Share	$ 0.65	$ 0.58	$ 1.82	$ 1.64
Diluted Earnings per Share	$ 0.63	$ 0.56	$ 1.77	$ 1.59
Anti-dilutive securities excluded from earnings per share calculation	81,874	147,737	85,765	251,576