Earnings Per Share (Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Earnings Per Share [Abstract]
Net income	$ 30,680	$ 27,518	$ 51,925	$ 43,811
Weighted average common shares outstanding	72,859,000	72,794,000	72,857,000	72,749,000
Dilutive effect of stock-based awards	553,000	445,000	544,000	441,000
Shares used in computing diluted earnings per share	73,412,000	73,239,000	73,401,000	73,190,000
Basic earnings per share	$ 0.42	$ 0.38	$ 0.71	$ 0.60
Diluted earnings per share	$ 0.42	$ 0.38	$ 0.71	$ 0.60
Number of antidilutive options that were excluded from computation of earnings per share	0	0	0	0