Earnings Per Share (Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Earnings Per Share
Net income	$ 27,518	$ 20,930	$ 43,811	$ 31,766
Weighted-average common shares outstanding	72,794,000	72,280,000	72,749,000	72,141,000
Dilutive effect of stock-based awards	445,000	487,000	441,000	517,000
Shares used in computing diluted earnings per share	73,239,000	72,767,000	73,190,000	72,658,000
Basic earnings per share	$ 0.38	$ 0.29	$ 0.60	$ 0.44
Diluted earnings per share	$ 0.38	$ 0.29	$ 0.60	$ 0.44
Number of antidilutive options that were excluded from computation of earnings per share	0	0	0	0