Earnings per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Reconcilement of the denominators of the basic and diluted EPS computations
Net income, basic	$ 8,983	$ 7,923
Weighted Average Common Shares, Basic	25,063	25,857
Basic, Per Share Amount	$ 0.36	$ 0.31
Add: potentially dilutive common shares - stock awards, Weighted Average Common Shares	75	22
Diluted, Net Income Available to Common Shareholders	$ 8,983	$ 7,923
Diluted, Weighted Average Common Shares	25,138	25,879
Diluted, Per Share Amount	$ 0.36	$ 0.31