Earnings Per Share (Schedule Of Computation Of Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Earnings Per Share [Abstract]
Net Income, Earnings	$ 20,445	$ 18,101
Net Income, Earnings, Shares	18,958,000	21,055,000
Net Income, Earnings per Share	$ 1.08	$ 0.86
Dilutive stock options, Shares	304,000	430,000
Nonvested stock awards, Shares	91,000	83,000
Net Income, Diluted earnings, Shares	19,353,000	21,568,000
Net Income, Diluted earnings per Share	$ 1.06	$ 0.84
Stock options excluded from computation of diluted earnings per share	1,400,000	979,000