Earnings Per Share (Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except 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	$ 25,128	$ 29,578	$ 77,053	$ 73,389
Weighted average common shares outstanding	72,879,000	72,811,000	72,864,000	72,770,000
Dilutive effect of stock-based awards	566,000	420,000	550,000	433,000
Shares used in computing diluted earnings per share	73,445,000	73,231,000	73,414,000	73,203,000
Basic earnings per share	$ 0.34	$ 0.41	$ 1.06	$ 1.01
Diluted earnings per share	$ 0.34	$ 0.40	$ 1.05	$ 1.00
Number of antidilutive options that were excluded from computation of earnings per share	0	0	0	0