Earnings Per Share (Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Net income	$ 38,264	$ 23,219	$ 66,071	$ 39,238
Weighted average common shares outstanding	72,144	72,227	72,289	72,209
Dilutive effect of stock-based awards	232	265	233	260
Shares used in computing diluted earnings per share	72,376	72,492	72,522	72,469
Basic earnings per share	$ 0.53	$ 0.32	$ 0.91	$ 0.54
Diluted earnings per share	$ 0.53	$ 0.32	$ 0.91	$ 0.54
Number of antidilutive options that were excluded from computation of earnings per share	0	0	0	0