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, 2013		Mar. 31, 2012
Earnings Per Share [Abstract]
Net income	$ 14,619		$ 34,773
Average shares used in basic computation	60,054		53,243
Dilutive effect of stock options and units	9,135		9,426
Average shares used in diluted computation	69,189		62,669
Basic	$ 0.24		$ 0.65
Diluted	$ 0.21	[1]	$ 0.55	[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.