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		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share [Abstract]
Net income	$ 37,710	$ 22,304	$ 98,619	$ 57,118
Average shares used in basic computation	53,601	52,367	53,471	52,610
Dilutive effect of stock options and units	9,453	10,785	9,346	10,564
Average shares used in diluted computation	63,054	63,152	62,817	63,174
Basic	$ 0.70	$ 0.43	$ 1.84	$ 1.09
Diluted	$ 0.60	$ 0.35	$ 1.57	$ 0.90