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, 2015		Mar. 31, 2014
Earnings per common share:
Net income	$ 43,097		$ 47,382
Average shares used in basic computation	68,006		66,037
Dilutive effect of stock options and units	9,353		9,654
Average shares used in diluted computation	77,359		75,691
Earnings per common share: Basic	$ 0.63		$ 0.72
Earnings per common share: Diluted	$ 0.56	[1]	$ 0.63	[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.