Summary Of Significant Accounting Policies (Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Net income	$ 265,636	$ 252,521	$ 254,690
Weighted average shares outstanding - basic	87,227	89,561	92,067
Dilutive effect of stock plans	1,742	1,941	2,127
Weighted average shares outstanding - diluted	88,969	91,502	94,194
Basic earnings per share	$ 3.05	$ 2.82	$ 2.77
Diluted earnings per share	$ 2.99	$ 2.76	$ 2.70
Anti-dilutive options	260	206	718