Earnings Per Share (Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net income	$ 47,514	$ 22,517	$ 113,585	$ 61,755
Weighted average common shares outstanding	71,436	72,298	72,001	72,239
Dilutive effect of stock-based awards	316	303	299	278
Shares used in computing diluted earnings per share	71,752	72,601	72,300	72,517
Basic earnings per share	$ 0.67	$ 0.31	$ 1.58	$ 0.85
Diluted earnings per share	$ 0.66	$ 0.31	$ 1.57	$ 0.85
Number of antidilutive options that were excluded from computation of earnings per share	0	0	0	0