Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share ) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Earnings Per Share [Abstract]
Net income	$ 34,773		$ 31,398
Average shares used in basic computation	53,243		52,534
Dilutive effect of stock options and units	9,426	[1]	10,645	[1]
Average shares used in diluted computation	62,669		63,179
Basic	$ 0.65		$ 0.60
Diluted	$ 0.55	[1]	$ 0.50	[1]

[1] Diluted earnings per share is computed on the basis of the weighted average number of shares of common stock plus the effect of dilutive potential common shares outstanding during the period using the treasury stock method. Diluted earnings per share include stock options and units.