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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net income	$ 18,920	$ 32,076	$ 57,318	$ 87,066
Weighted average common shares outstanding	72,058	71,890	72,043	71,967
Dilutive effect of stock-based awards	348	588	321	579
Shares used in computing diluted earnings per share	72,406	72,478	72,364	72,546
Basic earnings per share	$ 0.26	$ 0.45	$ 0.80	$ 1.21
Diluted earnings per share	$ 0.26	$ 0.44	$ 0.79	$ 1.20
Number of antidilutive options that were excluded from computation of earnings per share	0	0	0	0